De/Anti-Icing of Aircraft on Ground Manual
De-icing & Anti-icing of Aircraft on Ground Trainings Manual Tirana International Airport Tirana International Airport Nënë Tereza Administration Building, RinasAlbania Phone: +355 4 2381 600 Fax: +355 4 2381 545 E-Mail: info@tirana-airport.com Web site: www.tirana-airport.com
Date: 25.11.09 Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
Tirana International Airport SHPK Tirana International Airport Nënë Tereza, Administration Building, Rinas, Tirana, Albania
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De/Anti-Icing of Aircraft on Ground Manual Division/Department: Ground Handling Department Person responsible: Igli Larashi Tirana International Airport SHPK Tirana International Airport Nënë Tereza Rinas, Tirana Albania Phone: 00355 4 2381 600 Fax:
00355 4 2381 545
E-Mail: info@tirana-airport.com www.tirana-airport.com
Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
Tirana International Airport SHPK Tirana International Airport Nënë Tereza, Administration Building, Rinas, Tirana, Albania
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De/Anti-Icing of Aircraft on Ground Manual
Dear Staff and collegues, This presentation has been prepared with atmost care between Austrian Airlines maintenance team experts and Tirana International Airport Ground Handling Department. However, no claims can be filed, based on the content of this presentation since this manual contains material which is intended only for the training. It is not to be reproduced or distributed for use by others without written permission of author Mr. Igli Larashi (ilarashi@tirana-airport.com) The information contained in this publication is intended for training purposes only and does not supersede any maintenance or other approved technical publications. It is based on the requirements defined in JAR OPS 1345 and is consistent with similar information published by the Association of European Airlines (AEA 24-th Edition) in their document 'Recommendations for the De-/Anti-icing of Aircraft on the Ground', the International Standards Organisation (ISO) in ISO 11076 and the Society of Automotive Engineers (SAE) in ARP 4737. The Tirana International Airport Ground Handling Department training can not be responsible for misinterpretations in this presentation. Best and sincere regards
Igli LARASHI
Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
Tirana International Airport SHPK Tirana International Airport NĂŤnĂŤ Tereza, Administration Building, Rinas, Tirana, Albania
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De/Anti-Icing of Aircraft on Ground Manual
Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
Tirana International Airport SHPK Tirana International Airport NĂŤnĂŤ Tereza, Administration Building, Rinas, Tirana, Albania
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De/Anti-Icing of Aircraft on Ground Manual
Table of Contents Page 1.
Introduction
4
2.
Basic knowledge of aircraft performance
7
3.
Effects of Frost, Ice, Slush and Snow on aircraft performance
8
4.
Meteorological influence on ice formation
13
5.
Operational responsibilities for required types of Checks
18
6.
Aircraft dispatch requirements
20
7.
Checks for the NEED to de-ice
21
8.
Basic characteristics of de-icing and anti-icing fluids
23
9.
De-icing and Anti-icing procedures in general
26
10.
General techniques for de-icing and for anti-icing procedure
28
11.
Basic requirements and specific measures on different a/c types
34
12.
Critical areas of aircraft
36
13.
Safety Precautions and Emergency requirements
38
14.
Holdover Time
40
15.
De-/-anti-icing fluids Application and Limitations
42
16.
Check of Fluid Concentrations
44
17.
Post de-/-anti-cing Checks before aircraft depature
46
18
Anti-icing codes and communication procedures
48
19.
Fluid handling and storage requirements
50
20.
Effects of Sub-Zero Fuel and local frost prevention
51
21.
Evironment
54
22.
New procedures and development
56
23.
Personnel Health and Safety
57
24.
Quality Assurance Programme
58
Appendices:
63
a)
Aircraft Familiarisation Diagrams
64
b)
Aircraft de-/anti-icing - “NO SPRAY “areas
71
c)
Holdover Time Tables
76
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De/Anti-Icing of Aircraft on Ground Manual
1.0. Introduction "Flight Safety may be compromised if de-/anti-icing is improperly performed. It is therefore mandatory that all personnel involved receive both initial and recurrent training, in order to ensure they obtain (and retain) a thorough understanding of aircraft ground de-/anti-icing policies and procedures"
Today flying is inherently safe, although winter adds another dimension! Aircraft are designed to fly safely and efficiently during the various phases of flight, however, wing design criteria do not allow for any contamination on the critical aerodynamic surfaces and aircraft manufacturers stipulate that they must be free of all forms of frost, ice, slush and snow at take-off. Frozen contaminants, adhering to wing upper surfaces during takeoff roll, have been cited as the probable cause in a significant number of the aircraft accidents that have occurred over the past 30 years. With the Worldwide route network now expanding around the globe to satisfy newly emerging markets, it is essential that designated responsible persons regularly review the situation at the 'Cold Weather' Stations under their control. Critical issues such as training procedures and responsibilities shall be addressed on an annual basis, to ensure that all members of the 'team' are fully briefed and competent. Those delegated responsibilities in this area should be aware that this is a mandatory requirement under JAR-OPS. With the emphasis on 'Safety', it is vital that all de-/anti-icing operations be carried out exclusively by trained and qualified personnel. It is the responsibility of Operators to ensure that personnel responsible for both the de-icing operation and subsequent release of the aircraft have received both initial and recurrent training, in order to ensure they obtain and retain a thorough knowledge of aircraft ground de-/anti-icing requirements, policies and procedures. Records of personnel training and qualification shall be maintained by Line Maintenance Managers or by Station Managers for proof of qualification. Responsibilities for the delegation, regulation and control of aircraft ground De-/Anti-icing operations are defined in the Ground Operations Manual. This manual is intended to provide a common basis for de-icing/anti-icing training and qualification for de-icing providers and airlines. Each organization involved is responsible for complying with local regulations and requirements imposed by manufacturers of aircraft, equipment and fluids, by regulatory and environmental authorities. Reference material used in this manual includes common industry standards and recommendations, regulatory requirements and advisories. In particular, the AEA “Recommendations for the De-icing/anti-icing of Aircraft on the Ground” are used as reference for recommended de-icing procedures. No reference is made to any specific instruction or recommendation given by manu-facturers of aircraft, equipment or fluids. This must also be taken into account. This manual contains a summary of operational procedures. Because of the large variety of procedures, standards and Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
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De/Anti-Icing of Aircraft on Ground Manual recommendations, it is impossible to include each element and cover all aspects. The history of winter operations clearly shows that de-icing/anti-icing plays a vital role when it comes to the safety of the flight. Regrettably even within the past years incidents and accidents have happened due to improper winter operation procedures. Investigaions has shown the causes to be deficiences such as inspection or the determination for the need of de-icing/anti-icing, the de-/-anti-icing procedure itself and the negligence/misinterpretation of holdover time. Factors leading to these errors are, for example, poor training, miscommunication, improper de-/-anti-icing, fluid degradation, misinterpretation of tables and manuals etc. De-icing/anti-icing procedures are not just the concern of Northern countries. Even in warm countries, frost and icecan build up on aircraft wings after a long flight at altitude. De-icing is a worldwide issue. It is clear that de-icing is not a regional issue but an international one. Many organisations, companies and individuals have performed valuable reseach and contributed to the safety of icing related issues. Further work is needed to establish universal and comprehensive standards for all aspects of de-/-anti-icing Even if regulation of de-icing/anti-icing operations on ground is not stated in detail it is clear by everyone involved that icing related issues are to be considered as a critical matter. Many rules and limitations have been set for flight operations. Ground operations relating to de-/-anti-icing must be considered equally important because it is the first step of assuring a safe flight. Many organizations are working towards this common goal, safety of flight, and some of these organizations involved are AEA, SAE, ISO, EASA, JAA, FAA, ICAO, TC, NASA etc.
1.1.
References to common standards.
Wherever in this document fluid types I, I I , I I I , or IV are indicated, this always refer to the latest version of the applicable ISO and SAE fluid types. ( For example : Type I fluid refers to ISO Type I per ISO 11075 as well as SAE type I per AMS 1424. Type II fluid refers to ISO type II per ISO 11078 as well as SAE type II per AMS 1428. Type I I I and Type IV fluid only refers to SAE Type I I I and Type IV respectively per AMS 1428.) Copies of the SAE publications are available from: SAE, 400 Common Wealth Drive, Warrendale, PA 15096-0001, USA. Fax No: +1-412-776 0243, Phone No: +1-412-776 4841. : See also www.sae.org AMS 1424, de-icing/anti-icing fluid, aircraft, SAE type I. AMS 1428, Fluid, aircraft de-/anti-icing, non newtonian, (pseudoplastic), SAE Types I I, I I I , I V . ARP 4737, Aircraft de-icing/anti-icing methods. ARP 1971, Aircraft deicing vehicle - self-propelled, large capacity. ARP 5149, Training Program Guidelines for de-/anti-icing of aircraft on ground (Draft). AIR 9968, Field Viscosity Test of thickened de-icing/anti-icing fluid (Draft). ARD 50102, Forced air or forced air/fluid equipment for removal of frozen contaminants. Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
Tirana International Airport SHPK Tirana International Airport NĂŤnĂŤ Tereza, Administration Building, Rinas, Tirana, Albania
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De/Anti-Icing of Aircraft on Ground Manual
Copies of the ISO documents are available from: International Organization for Standardization, Case Postale 56, CH-1211, Geneve 20, and Switzerland. See also www.iso.ch ISO 11075:2007, Aerospace - Aircraft de-icing/anti-icing Newtonian fluids, ISO Type I. ISO 11076:2000, Aerospace - Aircraft de-icing/anti-icing methods with fluids. ISO 11077:1993, Aerospace - Self-propelled de-/anti-icing vehicles – functional requirements. ISO 11078:2007, Aerospace - Aircraft de-icing/anti-icing non-Newtonian fluids, ISO Type II.
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De/Anti-Icing of Aircraft on Ground Manual
2.0. Basic knowledge of aircraft performance. 2.1. General. The specific performance of any aircraft is calculated and tested with the assumption that all of its aerodynamic surfaces are clean. Any contamination will affect this performance and such a decrease in performance and control has not necessarily been assessed. The clean aircraft concept must be very clear for a de-icing grond staff. As rule of the thumb “make it clean and keep it clean”.
2.2. Forces involved. An aircraft is subjected to 4 forces: Lift, Drag, Thrust and Weight. For an aircraft to fly straight and level, all these forces must balance. A change in any one of these forces will affect (break) this balance. This change can be either intended or unintended (e.g. icing). Frost, snow, slush or ice formation has a negative effect on all these forces. Lift decreases, drag increases, weight increases and available excess thrust decreases. Contamination also affects the stall angle of attack by decrea-sing it, which could be very harmful at Take-off. It is up to the de-icing crew to clean the aircraft and protect it so that it will be aerodynamically “CLEAN” UNTILL take-off, after which the Flight Crew can operate the aircraft`s own anti-icing systems to protect the critical parts of the aircraft.
2.3. Basic aerodinamics. The critical effects of contamination are the resulting decrease in lift and manoeuvrability. The leading edges of the wing and of the vertical and horizontal stabilizers are the most critical areas with regard to the airflow around the aircraft. This part is where the airflow is divided evently around the wing surfaces (or tail surfaces). As the angle of a wing to the airflow (the angle of attack) is increased, the air flows evently along the surfaces at first (called laminar), but then after a certain point starts to break away (called turbulent) depending on the angle of attack. Any contamination at the leading edge will upset (disturb) this flow and it will break off earlier than intended causing a loss of Lift. The aircraft moves around three axes: Longitudinal, Horizontal and Vertical. The Flight Crew controls this movement by changing the position of the ailerons, rudder elevator depending on the particular flight situation. Any contamination on these control surfaces may restrict their movement or cause them to be ineffective (because of incorrect airflow) and in worst case cause a loss of control. Many aircrafts designed in different ways but the basic lifting physics remain the same. Any part on the aircraft that changes the airflow is there for a reason and de-icing ground staff must assure that these parts are free of contamination whether they are considered a critical liftingsurface or not. Such other aerodynamic parts on an aircraft can be strakes, vortions, winglets, pylons, stall strips or vanes, vortex generators etc.
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De/Anti-Icing of Aircraft on Ground Manual
Picture 1:
An aircraft flies because the air flowing over its wings generates Lift. To achieve this pre-calculated upward directional force and to maintain the additional safety reserves needed, it is a pre-condition that the aircraft's 'critical' surfaces are 'smooth and clean', prior to the start of the take-off roll. This requirent applies to the wings, as well as the horizontal and vertical tail surfaces.
Picture 2:
During ground icing conditions deposits of frost, ice, slush and snow can accumulate on the critical wing/tail surfaces, changing the profile and creating a rough surface which disturbs the smooth flow of air across the surfaces. This effectively reduces Lift and increases Drag.
Picture 3 : As a result, aerodynamic safety margins, in regard to acceleration and lifting performance, will either be reduced or completely eliminated. In the worst case frozen deposits can cause the aircraft to stall.
3.0
Effects of Frost, Ice, Slush and Snow on aircraft Performance.
3.1. How contamination affects Lift and Performance. It has been stated that any contamination will negatively affect Lift and Performance. It is logical that a large amount of snow, slush or ice will pronounce this effect, but even light contamination such as frost has a negative effect. Increase in Drag and Weight has its own consequences but our main concern is is the SAFETY of FLIGHT, not so the economical or other aspect of performance. Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 10 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
Tirana International Airport SHPK Tirana International Airport NĂŤnĂŤ Tereza, Administration Building, Rinas, Tirana, Albania
De/Anti-Icing of Aircraft on Ground Manual As said, it is common sense, that large amounts of contamination (snow, slush and ice) will affect Lift and Performance. So we will cover in more details that not so important effect of something as “simple” frost. Aircraft have been designed to be more efficient and economical which has lead to an airfoil design that is much more critical in producing Lift than what aircraft where designed decades ago.
3.2. Frost affecting Lift of aircraft. Test has been performed on how a different thickness of Frost affects lifting performance. The effect on other types of aircraft may be similar, this particular example happens to compare the performance of a narrow body jet aircraft. There three scenarios were compared: with clean wing, with a thin layer of frost (about 1 mm or less) and with a thick layer of frost (e.g. 1-2,5 mm). First normal take-offs with these layers were compared, then take-offs with an engine-out situation with the same layers. Commercial airliners are fitted with powerful engines that in normal cases produce a certain amount of excess thrust. This is seen as only a marginal lift-loss in normal take-off situations. A thick layer of frost has some effect on normal lifting performance but it is not dramatic. However, when there is engine-out situation with these contamination layers, it can be seen that even a thin layer of frost may have a notable effect on Lift compared to a clean wing under these conditions.When there is a thick layer of frost during an engine-out on take-off, lifting capabilities may be dramatically reduced. It must be noted that these situations may differ greatly netween different aircrafts and in some cases frost may be allowed to some extent. Aircraft manufacturer`s limitations shall be noted in all cases.
3.3. Other effects on Performance. It is clear that contamination will affect the amount of Drag on an aircraft. The more contamination located on an aircraft - the more Drag and thus worse performance. This contamination does not have to be on aerodynamic surfaces (which must be cleaned anyway) toto create Drag. It can be on the landing gear, fuselage etc. These areas must be cleaned, but as an example, it it can produce Drag even, if it does not directly affect Lift. Thrust must always be added (if excess thrust is available to compensate for the reduced performance. This is perhaps even more notable on propeller aircraft. The propeller is in itself a lifting device and its surface must be clean (the proper cleaning procedures according A/C manufacturer`s requirements). Any contaminationsof the blade surface can reduce the pulling force effectiveness of the propeller. Vibration of the propellers due to contamination may also be a factor to note. The same applies for jet driven aircraft. A visual check of the fan blades and especially on the rear side of the fanblades is necessary to detect frozen contamination adhering to them. This can lead to vibration, performance loss and even engine damage.
3.4. Results of Aircraft contamination. Failure to remove deposits of frost, ice, slush and snow from aircraft surfaces, prior to take-off, could result in:
•
Degraded aerodynamic performance
•
Restricted control surface movement
•
Blocked sensors
•
Ingestion damage to engines
•
Damage to vertical or horizontal tail surfaces
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De/Anti-Icing of Aircraft on Ground Manual
•
Increased weight and/or altered balance characteristics.
Degraded aerodynamic performance Test data from the aircraft manufacturers indicates that frost, ice or snow deposits having a thickness and surface roughness similar to medium to course sandpaper on the leading edge can reduce wing lift by as much as 30 % and increase drag by as much as 40 %.
These changes in lift and drag significantly increase stall speed, reducing controllability and alter aircraft flight characteristics. Thicker or rougher frozen contaminants can have increasing effects on lift, drag, stall speed, stability and control, with the primary influence being surface roughness on the critical portions of the aerodynamic surface. These adverse effects on the aerodynamic properties of the airfoil may result in sudden departure from the commanded flight path and may not be preceded by any indications or aerodynamic warning to the pilot. Loss of Lift -
Frozen accumulations may destroy the lifting ability of airfoils, including leading edge devices, resulting in failure of the aircraft to become airborne.
Increased Drag calculated/available
An aircraft may fail to reach takeoff speed within the distance, as a result of the increased drag placed on the airfoil due to the presence of frozen contaminants.
Decreased control -Frozen accumulations may impair the function of control surfaces, such as rudder, elevators, and ailerons and trim tabs, to such a degree that the aircraft cannot be controlled. Flutter in
Accumulation of frozen contaminants may create conditions that result separation of airflow and dynamic instability of the airfoil surface which, in extreme cases, can cause destruction of aircraft parts. Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
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De/Anti-Icing of Aircraft on Ground Manual Restricted control surface movement Ice deposits may form in hinge areas of control surfaces and restrict or prohibit their movement.
Blocked sensors Frozen contaminants blocking pitot probes, static ports, engine pressure sensing probes and inlets can cause errors in critical instrument readings.
Ingestion damage to engines Ice, shedding from the lower surface of the engine intake during take-off, can damage blades, vanes and other engine parts and in extreme cases may result in loss of the engine during this most critical stage of flight.
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De/Anti-Icing of Aircraft on Ground Manual
Damage to horizontal or vertical tail surfaces Deposits of clear ice that have formed on the upper surface of 'cold' wings during periods of rain, may be 'shed' during take-off and damage horizontal and vertical tail surfaces.
Increased weight and/or altered balance characteristics The build up of frozen contaminants on aircraft surfaces increases the weight of the aircraft and may affect its ability to reach take-off speeds within the required/available distance. It will also affect the distribution of weight on the aircraft.
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De/Anti-Icing of Aircraft on Ground Manual
4.0. Meteorological influence on ice formation. 4.1. Definitions For the purposes of this document, the following definitions apply.
:
4.1.1. Active frost: Active frost is a condition when frost is forming. Active frost occurs when aircraft surface temperature is: at or below 0 °C and at or below dew point. 4.1.2. Anti-icing: Precautionary procedure which provides protection against the formation of frost or ice and accumulation of snow or slush on treated surfaces of the aircraft for a limited period of time (holdover time). 4.1.3. Anti-icing fluid: - Type I fluid; - mixture of water and Type I fluid; - Type II fluid, Type III fluid, or Type IV fluid; - mixture of water and Type II or Type IV fluid.
:•
NOTE : Fluids mentioned in a) and b) must be heated to ensure a temperature of 60 °C minimum at the nozzle. Check: An examination of an item against a relevant standard by a trained and qualified person. 4.1.4. Cold-soak effect: The wings of aircraft are said to be "cold-soaked" when they contain very cold fuel as a result of having just landed after a flight at high altitude or from having been re-fuelled with very cold fuel. Whenever precipitation falls on a cold-soaked aircraft when on the ground, clear icing may occur. Even in ambient temperatures between -2°C and +15°C, ice or frost can form in the presence of visible moisture or high humidity if the aircraft structure remains at 0°C or below. Clear ice is very difficult to be detected visually and may break loose during or after take-off. The following factors contribute to cold-soaking: temperature and quantity of fuel in fuel cells, type and location of fuel cells, length of time at high altitude flights, temperature of re-fuelled fuel and time since re-fuelling. 4.1.5. Contamination: in this document is understood as all forms of frozen or semi-frozen moisture such as frost, snow, ice or slush. 4.1.6. Contamination check: Check of aircraft surfaces for contamination to establish the need for de-icing. 4.1.7. De-icing: Procedure by which frost, ice, slush or snow is removed from an aircraft in order to provide clean surfaces. 4.1.8.De-icing/anti-icing: Combination of the 'deicing' and 'anti-icing'. It may be performed in one or two steps. 4.1.9 De-icing fluid: '•- heated water; - type I fluid; -mixture of water and type I fluid; - type II, type III, or type IV fluid; - mixture of water and type II, type III, or type IV fluid. Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
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De/Anti-Icing of Aircraft on Ground Manual NOTE: efficiency.
De-icing fluid is normally applied heated in order to assure maximum
4.1.10 Freezing drizzle: Fairly uniform precipitation composed exclusively of fine drops (diameter less than 0.5 mm) very close together which freezes upon impact with the ground or other exposed objects. 4.1.11. Freezing fog: defined as a cloud of supercooled water droplets which freeze upon impact to form rime ice on objects in cold weather conditions. The visibility at the earth's surface is generally reduced to less than 1 km. The severity of this condition is dependent on the visibility and airflow. When moist air is blown into contact with a surface which is at or below 0°C , the supercooled droplets will freeze immediately. Where wind speed and direction are maintained for a period of time, a significant layer of rime ice can build up in a relatively short period of time. Clearly, the lower the visibility and/or the higher the speed of the airflow, the more severe the ice build up. 4.1.12. Frost/hoarfrost: Ice crystals that form from ice saturated air at temperatures below 0°C by direct sublimation on the ground or other exposed objects. 4:1:13 Hail: Precipitation of small balls or pieces of ice with a diameter ranging from 5 to >50 mm falling either separately or agglomerated. 4.1.14 Holdover time: Estimated time for which an anti-icing fluid will prevent the formation of frost or ice and the accumulation of snow on the protected surfaces of an aircraft, under weather conditions as specified in section 3.15. 4:1:15 Ice pellets: Precipitation of transparent (grains of ice), or translucent (small hail) pellets: of ice, which are spherical or irregular, and which have a diameter of 5 mm or less. The pellets of ice usually bounce when hitting hard ground. 4.1.16 Light freezing rain : Precipitation of liquid water particles which freezes upon impact with the ground or other exposed objects, either in the form of drops of more than 0.5 mm or smaller drops which in contrast to drizzle, are widely separated. Measured intensity of liquid water particles is up to 2.5 mm/hour or 25 grams/dm2/hour with a maximum of 0.25mm in 6 minutes. 4.1.17 Moderate and heavy freezing rain : Precipitation of liquid water particles which freezes upon impact with the ground or other exposed objects, either in the form of drops of more than 0.5 mm or smaller drops which, in contrast to drizzle, are widely separated. Measured intensity of liquid water particles is more than 2.5 mm/hour or 25 grams/dm2/hour. Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
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De/Anti-Icing of Aircraft on Ground Manual 4.1.18 Rain and snow: precipitation in the form of a mixture of rain and snow. 4.1.19 Snow : Precipitation of ice crystals, most of which are branched, ater-shaped or mixed with unbranchedcrystals. At temperature higher than -5°C, the crystals are generally agglomerated into snowflakes. 4.1.20 Snow grains: Precipitation of very small white and opaque particles of ice that is fairly flat or elongated with a diameter of less than 1 mm. When snow grains hit hard ground, they do not bounce or shatter. NOTE: for Holdover Time purpose treat snow grains as snow. 4.1.21 Snow pellets : Precipitation of very small white and opaque particles of ice. The particles ae round or sometimes conical; their diameter range from about 2-5 mm. Snow pellets are brittle, easily crushed; they do bounce and may break on hard ground. 4.1.22 Slush: snow or ice that has been reduced to a soft watery mixture. 4.1.23 Sleet: precipitation in the form of a mixture of rain and snow. 4.1.24.Freezing conditions: defined as OAT below +3°C and visible moisture in any form (such as fog with visibility below 1.5 km, rain, snow, sleet or ice-crystals) or when standing water, slush, ice or snow is present on the runway. 4.1.25 Frost : ice crystals formed from water vapour that freezes on surfaces which are at or below 0°C. On a cold cloudless night aircraft surface temperatures may fall to as much as 4°C below the ambient temperature, due to the effect of long wave radiation (heat in the wing effectively radiates through the atmosphere to outer space). Frost may therefore form on aircraft surfaces, even though the outside air temperature is +4°C. In addition, where wing surfaces are at or below 0°C, due to the presence of 'supercooled' fuel from the previous sector, frost will tend to form on these surfaces, when the ambient temperature is above that of the wing. 4.1.26 Rain on a cold soaked wing : water droplets from rainfall forming an ice topping on the wing upper surface, when the temperature of the aircraft wing surface is at or below 0°C. This phenomenon has been experienced at OAT’s of up to and above +15°C and will generally only occur when significant quantities of cold fuel remain from the previous sector.
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De/Anti-Icing of Aircraft on Ground Manual
4.1.27 Abbreviations: FP OAT °C
-
frezzing point; outside air temperature; Degrees of Celsius.
4.2. Relevant weather aspects. Weather is a complex and at times to difficult to understand. Our restless atmosphere is almost constantly in motion as it strives to reach equilibrium. These never-ending air movements set up chain reactions, which culminate in a continuing variety of weather. The climate of any particular region is largely determinated by the amount of energy received from the sun, but the local geography of the area also inflyences the clmate. We are prepared to face “problems” in areas where winter weather aspects are not so obvious. The main point is to be aware of how, where and why ice, in its different forms (and relating forms of frost and snow), can buid up on aircraft surfaces. Weather information can be gathered from various sources. Some of this written information can be difficult to understand at times, but they all follow the same logic. As for the de-icing crew temperature, dewpoint, precipitation, intensity and forecast information are elements that affect the operation. Meteorological report may be taken from the automated weather service (VHF-frequency at the airport), weater charts, weather radar etc. Even if this weather sampling is not an everyday routine for everyone it is important that some one informs the de-icing crew of the official and correct temperatures in order to use correct glycol mixtures. It is also important to refer to the right weather column for holdover times. This information should be updated as weather and temperature situations change.
4.3. Weather effects on aircraft operations. Weather operation in harsh climates is bound to affect the punctuality of any airline. Not only is ground operations impaired but also snow and ice on apron, taxiway and runway areas affect aircraft operations as well. However, there is no short cut to a safe de-icing/anti-icing procedure on ground. Flights are, irrespective of season, in some cases restricted with a Certain Take-Off Time (CTOT). This “window” of depature causes undue pressure for the completion of ground procedures, but this shall not cause any diversions in normal and safe de-icing/anti-icing procedures. Heavy winter weather conditions make the de-icing ground procedure to be more a normal task than an exception to consider. Airline that do not operate Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
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De/Anti-Icing of Aircraft on Ground Manual on a regular basis to these areas might nmot be as aware of the importance for an appropriate inspection and treatment. Milder winter season in warmer regions do not rule out the importance of an equal de-icing/anti-icing performance as in other regions. De-icing/anti-icing procedures and their respective Holdover Timetables are set according to some weather elements. These tables do not necessarily cover all the phenomena that can be experienced during a winter season, but they give a compromise of choices where different elements can be included. Some weather elements do not include tested holdover times and caution should be used if any particular weather is in thiscategory.
4.4. Weather effects on fluid behaviour. WX not only causes the need for de-/-anti-icing, it will also affect the performance of the fluids. Each fluid has a particular holdover time. This holdover time is dependent on different weather factors. The fluid can withstand a certain amount of water (in forms of snow, slush, rain etc.) until it become so diluted (or saturated) that it no longer gives protection against freezing of fulfils aerodynamic criteria. Further, wind has its own affect on how even the fluid layer is on the surfacesand can also lower the actual outside air temperature. Very cold temperatures also limit the use of glycol (variable for different compounds) both for anti-icing and de-icing. The viscosity of glycol also changes with temperature (variable for different fluids) and it in turn affects how the fluid is sprayed and how it draines of the surfaces.
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De/Anti-Icing of Aircraft on Ground Manual
5.0. Operational Responsibilities for required types of Checks.
Checks for the need to de-ice - The basic responsibility for assessing whether an aircraft requires de-/anti-icing lies with the operating Captain. However, at those Stations where an Engineer carries out the pre-departure check, he/she will normally assist the Captain in determining if the aircraft requires de-icing. Under certain conditions, for example when 'clear ice' is likely to be present, the Captain may, at his discretion, call for the assistance of an Engineer, or suitably trained and approved person from Handling Company, in order that a close inspection of the wing upper surface can be made. On those occasions when the surfaces were found to be free of contamination during the preflight check, but precipitation/freezing occurred after doors closed, the person releasing the aircraft (Headset Operative) will assume responsibility for re-checking the appropriate surfaces, on behalf of the operating Captain. Where surfaces are found to be outside limits at this time, or are likely to be outside limits prior to take-off, the person carrying out the check shall request de-/-anti-icing, through the aircraft Dispatcher or Station Representative. Note:
There will be occasions, for example during frost conditions, when, for operational reasons, the aircraft may have been de-/-anti-iced prior to the arrival of the Flight Crew.
De-/-Anti-icing Operation - The De-icing Operative (nominated Leader of Operative Deicing Group, where more than one vehicle used) is responsible for ensuring that it is performed in accordance with Operator`s procedures (see ATP 688/2, “Operations in Snow & Ice Conditions” and the appropriate Aircraft Maintenance Manual) and that prescribed surfaces are free of frost, ice, slush and snow on completion of the operation. When the aircraft is de-/-anti-iced on, or just prior to departure, they will also be responsible for ensuring that the Anti-icing Code has been passed to the operating Captain, either via the person releasing the aircraft or directly. Post De-/Anti-icing Check - The Engineer, or suitably trained and approved person (split between the De-icing Operative/Lead De-icing Operative and Headset Operative), releasing the aircraft is responsible for establishing that appropriate surfaces are free of contamination, prior to the start of push/taxi and for notifying the operating Captain of the Anti-icing Code. This enables the Flight Crew to determine the likely 'holdover time', acts as their confirmation that the aircraft has been correctly de-/-anti-iced and that appropriate surfaces are free of frozen deposits. Pre-take-off Check - When icing conditions exist, either prior to or during departure/taxy, it is the responsibility of the operating Captain to satisfy himself/herself that specified aircraft surfaces remain free of frozen contaminants, until the start of the take-off roll. Where an aircraft has been de-/-anti-iced prior to departure, the following factors will require consideration : •
The type and concentration of de-/anti-icing fluid used (details of the second step fluid will be provided when a two-step de-/-anti-icing operation is performed). Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
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De/Anti-Icing of Aircraft on Ground Manual • • • •
•
The outside air temperature (OAT). The type and severity of freezing precipitation. The time that has elapsed between the start of de-/-anti-icing (start of the second step, when two-step operation performed) and the start of the take-off roll. Changing weather conditions, such as increases or reductions in the OAT or precipitation rate, or a change in the type of precipitation, e.g rain to freezing rain/freezing rain to rain or the end of precipitation. Other relevant factors such as the presence of a large quantity of 'supercooled' fuel in the aircraft wings, reducing the wing upper surface temperature to well below that of the OAT.
When significant freezing precipitation exists, representative surfaces, such as the aircraft wings, should be checked just prior to the aircraft taking the active runway or initiating the take-off roll, in order to confirm they have remained free of frozen contaminants. This is of particular importance where holdover times have either been exceeded or are about to run out. Where frozen deposits are seen to be forming/accumulating on upper wing surfaces and are no longer being melted by the glycol present in the de-/-anti-icing fluid, additional de-/anti-icing will be required. However, where there is no evidence of frozen contamination forming/accumulating on the surface of the wing, there will be no requirement for additional de-/-anti-ing to be carried out. Arrival Inspection - When slush is present on runways and taxiways, aircraft may arrive on stand with flaps/slats deployed. The reason for this is that the slush can be thrown up by the aircraft wheels and freeze where it contacts cold structure. Should this occur on either the upper or lower surfaces of the slats/flaps, there is potential for both the flaps and flap housings/falsework to be damaged by the frozen residues, during subsequent retraction. Where flaps/slats are partially deployed on arrival on the stand, the operating Captain will be responsible for calling for an Engineer, or suitably trained and approved person, to check that surfaces are free of frozen deposits/call for de-icing, prior to retraction. When an aircraft with turbo fan engines lands in freezing fog (or fog with OAT at or below 0° C) conditions, Flight Crew will inform the appropriate Engineering Control (where possible via company frequency), in order that the rear side of the fan blades can be checked for ice build up on arrival. Where present, Engineering will remove prior to the subsequent start-up.
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De/Anti-Icing of Aircraft on Ground Manual
6.0. Aircraft dispatch requirements
With the exception of the areas defined below, the aircraft must be free of all forms of frost, ice, slush and snow before take-off: •
Thin hoarfrost is acceptable on the surface of the fuselage, provided the static vents are clear.
•
Frost is permitted on the underside of the wing, provided it is confined to the general area of the fuel tanks and that the depth does not exceed 3mm (1/8").
Ice ridges that have formed underwing, due either to rain or melting frost, ice or snow running back and re-freezing in the vicinity of the fuel tanks, are not acceptable. Note: Thin hoarfrost is a uniform white deposit of fine crystalline texture through which fine surface features such as paint lines, markings or lettering can be distinguished. This must not be confused with rime ice, which may form on windward surfaces in freezing fog conditions and is not acceptable.
With regard to the above statement,"...through which fine surface features such as paint lines, markings or lettering can be distinguished, “it is important that all personnel appreciate that this alleviation only refers to thin hoar frost.
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De/Anti-Icing of Aircraft on Ground Manual
7.0. Checks for the NEED to De-ice. When conditions conducive to the formation of frozen deposits exist (see Section 4), aircraft surfaces shall be checked for evidence of frost, ice, slush and snow during the Flight Crew preflight walkround. Where frozen deposits, other than those defined below, are identified the aircraft will require de-/-anti-icing prior to t ake-off: Thin hoarfrost is acceptable on the surface of the fuselage, provided the static vents are clear. Frost is permitted on the underside of the wing, provided it is confined to the general area of the fuel tanks and that the depth does not exceed 3mm (1/8").
Where freezing conditions do not exist at the time of the Flight Crew pre-flight walkround but, due to a subsequent change in the weather, occur after 'doors closed', the person releasing the aircraft (Headset Operative) will assume responsibility for re-checking the appropriate surfaces, on behalf of the operating Captain. Ensure engine fan blades rotate freely. Serious engine damage may occur if water from melting ice/snow subsequently re-freezes, bonding the fan blades to the lower casing. It is important to establish that frozen deposits are present before requesting de-icing. Where surfaces are free of frozen deposits at this time and no precipitation is in evidence, de-icing will be unnecessary. De-icing should not be requested; solely on the basis that the A/C parked on the next stand is being de-iced! In addition A/C will not automatically require de-icing just because temperatures are at or below 0°C. Moisture, in the form of humidity or precipitation, will also be required before frozen deposits will form or accumulate and where no precipitation is present and the dew point is a number of points below OAT, surfaces will often be found to be 'frost free' on inspection. By definition an A/C can only be 'de-iced' when frozen deposits are in evidence. Where aircraft surfaces are outside limits they will require de-icing. In addition, where reasonable efforts have been made, either to confirm that appropriate surfaces have remained free of contamination, or that previously applied de-/-anti-icing fluid has not failed and doubt exists, they will require de-icing. Resources will generally be stretched when the potential exists for ground icing and any decision to de-/-anti-ice unnecessarily will invariably Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
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De/Anti-Icing of Aircraft on Ground Manual impact on the operation. Where a request to de-ice is made without first establishing that is necessary, both unnecessary expense and possibly a significant service delay may be incurred. It should be remembered that de-/anti-icing fluid is itself a form of contaminant and to apply it nnecessarily to clean surfaces will effectively reduce, rather than enhance, performance margins.
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De/Anti-Icing of Aircraft on Ground Manual
8.0. Basic characteristics of aircraft De-icing and Anti-icing Fluids. 8.1. Types of De-/Anti-icing Fluid and their Basic Characteristics There are currently four main types of de-/-anti-icing fluid: 1) ISO Type I fluid (un-thickened) - These fluids have high glycol content and a low viscosity in their concentrate form. De-icing performance is good but due to the low viscosity; provide only limited anti-icing protection during freezing precipitation. They are used predominantly for removing frozen deposits from aircraft surfaces, either as the first step in a two-step operation or where precipitation has stopped. As this is a simple Newtonian fluid that does not contain a thickening agent, no additional holdover time is provided by strengthening the mix. The only benefit would be that the freezing point would be lowered, due to the increased glycol level in the mix. Due to the composition of this fluid, no special handling requirements exist. 2) ISO Type II fluid (thickened) - These fluids generally have a lower glycol content in their concentrate form than Type I fluids, however, due to the inclusion of a 'thickening agent', they posses special rheological properties. This effectively means that when applied to the surfaces of an aircraft the viscosity is high, thus allowing the fluid to remain on and protect against freezing precipitation for a period of time. However, the increasing effect of the airflow over the wing during the take-off roll will effectively `shear`the fluid, reducing its viscosity and allowing it to readily flow off the critical surfaces. With this type of fluid the holdover time can be extended by increasing the concentration of fluid in the fluid/water mix.
ISO Type III fluid (thickened) - These fluids are similar in both composition and operation to Type II fluids. The purpose of this fluid is to give a reasonable protection, compared to Type-I, from refreezing.With the lower viscosity of this fluid, compared to Type-II and 窶的V, it is better suited for regional aircraft with lower takeoff speeds (<85 knots) or for aircraft with other restrictions on thickened fluids, e.g. such A/C as Dash 8 or ATR-72. The colour of type-III fluid is to be determined. Note: The current ISO Type III fluid specification refers to a low viscosity fluid, specifically for commuter aircraft with their lower rotational speeds.
4) ISO Type IV fluid (thickened) - These fluids are similar in both composition and operation to Type II fluids. However, through the use of advanced thickener systems they are able to provide more holdover time than Type II fluids, when used in concentrate form. As with Type II fluids the holdover time can be extended by increasing the concentration of fluid in the fluid/water mix. Type II, III and IV fluids are known as 'non-newtonian pseudo plastic fluids' which, in some respects, are similar to thixotropic (non-drip) paints. When initially applied the viscosity Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
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De/Anti-Icing of Aircraft on Ground Manual is high, thereby allowing the fluid to remain on and protect the aircraft surfaces for an extended period of time. However, as the aircraft accelerates during the take-off roll, the airflow over the surfaces increasingly 'shears' (breaks down the internal structure) of the fluid, significantly reducing its viscosity and thus allowing it to flow off. When the aircraft reaches rotational speed, the lifting surfaces are 'aerodynamically clean'. Due to the critical nature of the thickening agent in Type II, III and IV fluids, careful handling is required at the pre-aircraft stage to ensure that they are not degraded, either prior to, or during, application. The methods employed to store, transport, heat, pump and apply these fluids, must be in line with the fluid manufacturers recommendations, if the structure of the fluid is to be maintained in an acceptable condition from `delivery to take-off`. The basic effect of this type of degradation will be to reduce the viscosity of the fluid, thereby allowing it to flow off surfaces prematurely. This leaves the surfaces of the aircraft unprotected and therefore vulnerable to the effects of freezing precipitation. Under these conditions the published holdover times will not be achieved
8.2. De-icing Fluids and Anti-icing Fluids. De-icing Fluids:
-
Heated water; Heated mixtures of ISO Type I fluid and water; Heated concentrates or mixtures of ISO Type II fluid and water; Heated concentrates or mixtures of ISO Type IV fluid and water.
De-icing fluid is normally applied heated to assure maximum de-icing efficiency How do they work: In purely de-icing terms there is little difference between Type I and Type II/IV fluids. For maximum effect, the above fluids are normally mixed with water to a pre-determined ratio (see Section 14) and heated to as near 85°C as possible. In order to maximise the benefits from the heat, the fluids are applied as close to the surface of the aircraft as safely practical. The heat in the fluid effectively melts any frost, as well as light deposits of snow and ice. Heavier accumulations require the heat to break the bond between the frozen deposits and the structure. Once the bond has been broken, the hydraulic force of the fluid spray is used to flush off the frozen residues. Where glycol is present in the fluid (all above except water), it will effectively depress (lower) the freezing point of the residues. When a one-step de-/-antiicing operation is carried out, the glycol in the fluid will depress the freezing point to below the OAT, thus preventing the residues from re-freezing.
Anti-icing Fluids: - Mixtures of ISO Type I fluid and water; - Concentrates or mixtures of lSO Type II fluid and water; - Concentrates or mixtures of ISO Type IV fluid and water. Anti-icing fluid is normally applied cold, however, where de-/-anti-icing fluid is maintained in a heated condition for de-icing purposes, it may be applied hot when anti-icing. No appreciable reduction in holdover time will be experienced. How do they work : Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
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De/Anti-Icing of Aircraft on Ground Manual For anti-icing purposes the above fluids are normally applied either prior to the onset of a freezing condition or as the second step in a two-step operation. With regard to anti-icing there are significant differences between Type I and Type II/IV fluids. During precipitation glycol, remaining on the aircraft surfaces following de-/anti-icing will reduce the freezing point of the frozen deposits that settle on it, effectively melting them. This process continues, until the glycol has been diluted to the stage where it is no longer effective and frozen deposits will start to accumulate. With Type I fluid little fluid remains on the aircraft following either de-icing or anti-icing and therefore only minimum protection is provided. Type II/IV fluids, with their thickening agents and subsequent high viscosity, are able to form a much thicker liquid film, which will take significantly longer to dilute to the point where frozen deposits will start to accumulate. Caution: De-/-Anti-icing fluids from different manufacturers shall not be mixed!!!!!!!
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De/Anti-Icing of Aircraft on Ground Manual
9.0. De-icing and Anti-icing procedures in general. 9.1. De-icing procedure. De-icing - a process by which frost, ice, slush and snow is removed from the surfaces of an aircraft with a De-icing fluid, in order to provide 'clean' (uncontaminated) surfaces.
For maximum effect this fluid is normally diluted with water and heated to around 85°C for maximum effect. It is then applied close to the surface of the aircraft, in order to minimise heat loss. The heat is utilised to effectively 'melt' frozen deposits, or with 'frozen-on' ice or snow to break the bond between frozen deposit and structure. The 'glycol' in the de-icing fluid reduces the freezing point of the melting residues to below the ambient temperature and the hydraulic force of the fluid spray is then used to flush off the residues from the surface of the aircraft. Note :
Pre-step process to be done prior to de-icing. In VIE and outer station if agreed by the operator, a pre-step process prior to de-icing process, in order to remove large amounts of frozen deposits, may be considered to reduce the quantity of glycol based de-icing fluid that is needed. The pre-step process may be performed with various means (e.g. brooms, forced air, heat, heated water, and heated fluid with negative buffer freezing point). If the pre-step procedure is used, make sure that the subsequent deicing process removes all frozen contamination that may have formed on surfaces or in cavities due to the pre-step process. Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
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De/Anti-Icing of Aircraft on Ground Manual 9.2. Anti-icing procedure. Anti-icing - a procedure that provides protection against the formation of frost or ice and accumulations of slush or snow on 'clean' (uncontaminated) surfaces, for a limited period of time (holdover time).
For effective anti-icing an even film of undiluted (viscous) 'anti-icing fluid' is applied to prescribed aircraft surfaces, either prior to the onset of freezing conditions or as the second step in a two-step operation. The applied fluid will provide a barrier to minimise and in certain cases prevent the build-up of frost, ice or snow on the external surfaces of the aircraft. During periods of freezing precipitation, the glycol in the applied fluid film will depress (reduce) the freezing point of the frozen deposits that settle on it, effectively melting them. This process continues until the glycol has been diluted to the stage where it is no longer effective and frozen deposits will start to accumulate. In continuing precipitation frozen deposits will build-up on the film but will have no adhesion to the skin of the aircraft. It can therefore be easily removed by spraying with 'hot' de-icing fluid.
9.3. De-icing/anti-icing. De-/-anti-icing - combination of the procedures 'deicing' and 'anti-icing'. It may be performed in one or two steps.
9.4. One-step de-/-anti-icing. One-step de-/-anti-icing – de-icing and anti-icing are carried out at the same time using a hot de-/-anti-icing mix to both remove frozen deposits and to protect the de-iced surfaces for a period of time. The fluid concentration required on the day is selected wiyh regard to the holdover time required under the prevailing weather conditions and the OAT.
9.5. Two-step de-/-anti-icing. Two-step de-/-anti-icing – de-icing and anti-icing consists of two distinct steps. After the first step of de-icing procedure immediately follows the the second step of anti-icing procedure, as a separate fluid application. Anti-acing fluid is applied to protect the relavant surfaces, thus providing the maximum possible anti-icing capability.
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De/Anti-Icing of Aircraft on Ground Manual
10. General techniques for removing of frost, ice, snow and slush from aircraft surfaces and for anti-icing procedures. 10.1. De-icing - removal of frost and light deposits of ice A nozzle setting giving a solid 'cone' (coarse) spray is required. This ensures the largest droplet pattern available, thus retaining maximum heat in the fluid.
The fluid is applied as close to the aircraft skin as reasonably practicable and the spray traversed over the frozen deposits, in order to melt them. Depending on the type of equipment used, either position the nozzle over, or aim the gun at the area to be treated, before starting to spray and stop when the end of each sweep is reached. Note:
Do not drench the structure and surrounding area with vast quantities of fluid. This is totally unnecessary with this type of light deposit and both wasteful and expensive in terms of de-/anti-icing fluid.
10.2.De-icing – removal of snow and ice. General de-icing fluid application strategy: - the technique to be adopted on the day will depend on the type, e.g. wet and heavy or dry and light, the depth of snow to be removed and the type of equipment available. In order to establish whether snow is wet or dry, scoop up a handful of snow and attempt to make a snowball. If the snow readily forms into a ball when compressed, the snow can be considered as being wet snow. However, where the snow refuses to knit together to form a ball and immediately falls apart when released, it can be considered as dry snow. Wings/tail plane - spray from the wingtip inboard to the wing root, from the highest point of surface camber to the lowest. Vertical surfaces - start at the top and work down. Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
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De/Anti-Icing of Aircraft on Ground Manual Fuselage - spray along the top centreline and then work outboard. Landing gears and wheel bays - keep the application of de-icing fluid in this area to a minimum.Do not spray de-icing fluids directly onto wheels, brakes, bearings, cables, electrical connectors or other equipment. It may be possible to mechanically remove accumulations such as blown snow, however, where deposits have bonded to surfaces they can be removed by applying hot air or by careful application of hot de-icing fluid. Engines - deposits of snow should be mechanically removed from engine intakes prior to departure. Any frozen deposits that may have bonded to either the lower surface of the intake or the fan blades, may be removed by hot air or other means recommended by the engine manufacturer. If the use of de-icing fluid is permitted, do not spray directly into engine core. Light accumulations of snow - very light accumulations may be removed using a similar technique as for de-frosting, i.e. traversing a 'course' fluid sprays over the deposits to be removed. Using this procedure the heat is used to effectively melt the snow.
However, where this method is found to be ineffective, due to the amount of snow present, the nozzle should be adjusted to provide a fluid jet and the hydraulic force of the fluid used to flush-off the deposits. A relatively low flow rate will normally be found to be adequate for removing light accumulations of dry snow; however, it may be necessary to increase the flow rate when removing wet snow. Moderate accumulations of snow - for this type of deposit the nozzle should be adjusted to provide a fluid jet and a moderate flow rate selected.
The hydraulic force of the fluid jet is then used to flush-off the deposits with a side to side Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
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De/Anti-Icing of Aircraft on Ground Manual action adopted in order to create a 'bow-wave' effect. Using this technique the snow can be quickly removed from aircraft surfaces. Again, the flow rate may need to be increased when removing wet snow.
Heavy accumulations of snow - a similar technique to that adopted for removing moderate accumulations is utilised, however, for heavy accumulations a high flow rate is required in order to effectively `blast off `the deposits within an acceptable timescale. Due to the nature of wet snow, it will invariably take longer to remove than dry snow and significantly more fluid will be required.
'Frozen-on' snow/clear ice - when wet snow falls onto aircraft surfaces that are at or below 0°C , or when wet snow has built-up on aircraft surfaces and the ambient temperature subsequently drops to 0°C or below, the deposits will bond to the structure. This also occurs when drizzle/rain falls onto aircraft surfaces that at or below 0°C to form clear ice. Such deposits are extremely difficult to remove and a different technique is required. The high thermal conductivity of the metal skin is utilised and a jet of hot fluid is directed at close range onto one spot, until the bare metal is just exposed. This bare metal will then transmit heat laterally in all directions, raising the temperature above the freezing point and thereby breaking the adhesion of the frozen mass with the aircraft surface. By repeating this procedure a number of times the adhesion of a large area of frozen snow or clear ice can be broken. The deposit can then be flushed off with either a low or high flow fluid jet, depending on the amount of deposit to be removed. Do not attempt to melt off thick frozen-on snow or clear ice by continually traversing a fluid spray or jet over the deposits. Large amounts of fluid will be wasted if this method is adopted. It is important that the procedure detailed above is carried out under these conditions, as vast savings in both time and money will result.
10.3. Anti-icing. For effective anti-icing an even film of 'anti-icing' fluid is applied to prescribed surfaces. The high fluid pressures and flow rates normally associated with de-icing are not required for this operation and where possible pump speeds should be reduced accordingly.
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De/Anti-Icing of Aircraft on Ground Manual The nozzle of the spray gun will normally be adjusted to give a medium to fine spray pattern, however, in windy conditions, or where it is necessary to project the fluid over a greater distance, due for example to access problems, it may be found necessary to select a more concentrated spray pattern and a higher pressure. The major requirement is to apply the fluid uniformly to produce a constant even film over the surfaces. With most Type II fluids the amount required will be visually indicated by the fluid flowing over the leading edge and dripping from the trailing edge.
However, Type IV fluids generally have a higher viscosity on application and tend not to 'run-out' to form an even film. Application techniques are therefore rather more complicated and greater care will be required in order to ensure that the appropriate surfaces have a 'complete' cover, with no visible gaps. When anti-icing is carried out as the second step in a two-step operation, it is important that the first step fluid is effectively washed-off by the anti-icing fluid. A substantial reduction in holdover time may be experienced if this requirement is not met. This has proved to be a particularly serious problem when Type I fluid has been used for the first step.
When anti-icing the best results are obtained by commencing at the highest part of the wing section and covering from there towards the leading and trailing edges. On vertical surfaces start at the top and work down.
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De/Anti-Icing of Aircraft on Ground Manual
Surfaces to be protected are: 1. Wing upper surfaces and leading edges. 2. Horizontal stabiliser upper surfaces and leading edges and elevator upper surfaces. 3. Vertical stabiliser and rudder. 4. Fuselage upper surfaces, depending on amount and type of precipitation (especially important on centre engined aircraft). Note: Where snow or freezing rain is falling or forecast at the time of application, the fuselage will invariably require ant-icing, in order to ensure it remains free of frozen deposits until take-off. Caution: Under no circumstances can an aircraft that has been anti-iced with concentrate Type II or Type IV fluid receive a further coating of concentrate Type II or Type IV fluid directly on top of the existing film. Should it be necessary for aircraft surfaces to be re-protected, prior to the next flight, surfaces must first be de-iced with hot dilute fluid.
Picture 1: Correct position of Horizontal Stabiliser on B737/A320 Aircraft when removing Ice, Slush or Snow With the horizontal stabiliser in 'its' leading edge 'UP' position, melting residues of ice slush or snow, mixed with de-anti-icing fluid, will run off the trailing edge, leaving the balance panel/bay area free of contamination.
Picture 2: Incorrect position of Horizontal Stabiliser Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
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De/Anti-Icing of Aircraft on Ground Manual With the Horizontal Stabiliser in the neutral or leading edge 'DOWN' position, melting.residues of ice, slush and snow, mixed with de-icing fluid, will run forward from the vicinity of the trailing edges into the balance panel/bay area.
Picture 3:
Effect of de-icing with Horizontal Stabiliser in incorrect position
As the aircraft climbs, the potential exists for melting residues and de-icing fluid to freeze in the balance panel/bay area, due to the reducing OAT. This will have the effect of restricting control surface movement at a critical phase of flight.
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De/Anti-Icing of Aircraft on Ground Manual
11. Basic requirements and specific measures to be performed on different aircraft types.
1.
It is important to ensure that the engine fan assembly rotates freely. Serious engine damage may occur if water from melting ice/snow subsequently re-freezes, bonding fan blades to the lower casing.
2.
During freezing fog conditions, it will be necessary for the rear side of the fan blades to be checked for ice build up, prior to start. Any deposits found can be removed by directing air from a low flow hot air source, such as a cabin heater. Onto the effected area.
3.
Prior to the start of de-/anti-icing, first ensure that: a) Air Conditioning/APU air selected 'OFF '. b) Flaps/slats fully retracted. c) The horizontal stabiliser on B737 and A320 aircraft is positioned in the leading edge UP`(aircraft trimmed nose down) position, prior to removing ice, slush or snow from the upper surface (not required for a 'frost only' condition). Adoption of this procedure will prevent residues from accumulating in the balance bay areas, where they could subsequently freeze as the aircraft climbs. a) All doors and windows are closed. Note: Main engines are normally shut down during de-/anti-icing operations but may remain at idle to accommodate local airport procedures. The APU may be running.
4.
In order to avoid subsequent aerodynamic problems, it is vital that the aircraft is treated symmetrically at all times. That is the same fluid/fluid mix must be applied to both the left hand and the right hand sides of the aircraft and this fluid must be applied to the corresponding areas on both sides. Although frozen deposits may only be present on one side of the aircraft, the same procedure must be repeated on the other side, to ensure that the aerodynamic effect of the fluid remaining on the wing/tail surfaces during take-off is the same on both sides of the aircraft.
5.
Snow must be removed from the nose radome areas prior to departure, in order to prevent deposits from blowing back and obstructing the pilot’s vision on take-off. It is recommended that where practicable, this snow be removed by mechanical methods, such as with a long handled squeegee or soft bristled brush. This will effectively prevent the problems highlighted in item 6. from occurring.
6. Where possible avoid or restrict the spraying of Type II or Type IV fluids in the vicinity of flight deck windows, as residues will tend to smear the screens and subsequent use of windscreen wipers will invariably exacerbate the problem. When windscreens have inadvertently been contaminated during the de-/-anti-icing operation, they will require cleaning, prior to departure. Where appropriate, water and a soft cloth may be used; 7.Landing gears and wheel bays must be kept free from the build up of slush, ice or accumulations of blown snow. Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
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De/Anti-Icing of Aircraft on Ground Manual 8.
Ice can build up on control surfaces when descending through thick cloud or precipitation during an approach. When ground temperatures at the destination are low, it is possible for flaps to be retracted and for accumulations of ice to remain undetected between stationary and movable surfaces. It is therefore important that these areas are checked prior to departure and any frozen deposits removed.
9.
Under freezing fog conditions it is necessary for the rear side of the fan blades to be checked for ice build-up prior to start-up. Any deposits discovered are to be removed by directing air from a low flow hot air source, such as a cabin heater, onto the affected area.
10. When slush is present on runways, inspect the aircraft when it arrives at the ramp for slush/ice accumulations. If the aircraft arrives at the gate with flaps in a position other than fully retracted, those flaps which are extended must be inspected and if necessary de-iced before retraction. 11. A functional flight control check, using an external observer, may be required after de-icing or anti-cing, depending upon aircraft type (see relevant aircraft maintenance manual). This is particularly important in the case of an aircraft that has been subjected to an extreme ice or snow covering. 12. Always give symmetrical treatment to wings, stabilizer and fuselage. 13. A thin layer of frost on the upper part of fuselage is permitted, as long as the painted markings or letters are visible on the fuselage surface. 14. A layer of frost not exceeding 3 mm thickness on lower wing surface is permitted within the wing tank areas. 15. If de-icing for DC-9, MD-80, MD-90 is required on any other aircraft surfaces, it is recommended, that underwing frost should also be removed. EXCEPTION :When de-/-anti-icing completed on frost-coated upper wing or stabilizer surfaces with heated undiluted Type II/IV fluid in non-precipitation condition, it is not necessary to remove frost from lower tank surface provided, that it is less than 3 mm .
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De/Anti-Icing of Aircraft on Ground Manual
12. Critical areas of aircraft. Basically all surfaces of aircraft, that have an aerodynamic-, control-, sensing-, movement- or measurement-function must be clean. All of these surfaces can not necessarily be cleaned and protected in the same conventional de-icing manner as, for example, the wings. Some areas require only a cleaning operation while other need protection against freezing. The procedure of de-icing may also vary according to aircraft limitations (see AMM). The use of hot air may be required when de-icing e.g. landing gears, engine fan blades or propellers. Caution: Frost and ice may form on both upper and lower wing surfaces under any ambient condition if the fuel in the tanks is sufficiently cold. Some critical elements and procedures to follow, common for most aircrafts listed below:
1.
Any forward area from which fluid may blow back onto windscreens during taxy or subsequent take-off must be free of fluid residues, prior to departure.
2.
DO NOT direct solid fluid stream at right angles to the surface. Apply at a low angle to prevent damage to aircraft.
3.
DO NOT spray de-/-anti-icing fluids directly onto hot brakes, wheels, exhaust stacks or thrust reversers.
4.
De-/-anti-icing fluid must not be directed into the orifices of pitot heads, static vents or directly onto airstream direction detector probes/angle of attack, airflow sensors.
5.
ALL reasonable precautions must be taken to minimise fluid entry into engines, other intakes/outlets and control surface cavities.
6.
DO NOT spray fluids directly onto flight deck or cabin windows as this can cause crazing of acrylics or penetration of the window sealing.
7.
Ensure the application of de-/-anti-icing fluid in the vicinity of the landing gear and wheel bays is kept to a minimum. DO NOT sprays de-/anti-icing fluid directly onto wheels, brakes, bearings, cables, electrical connectors or other equipment.
8.
DO NOT allows de-/-anti-icing fluids to run into wheels or break heat packs. The fluid can cause serious damage to carbon brakes and reduce braking performance for both carbon and steel brakes.
9.
Extreme care must be exercised when spraying de-/-anti-icing fluid in the vicinity of APU intakes, even when the APU has been shut-down. Residues of fluid sprayed in the vicinity of the intake/intake door can enter the intake and when the APU is subsequently started, lead to smoke in the cabin and in the exhaust fumes. Note:
Smoke in the Cabin has lead to emergency evacuation of passengers and smoke in the exhaust to the emergency services being called by the Control Tower.The APU intake on the B777 is particularly vulnerable to the effects of fluid ingestion, due to the location/design of the intake. Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
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De/Anti-Icing of Aircraft on Ground Manual 10. Ice can form on an aircraft's surface below a layer of snow or slush. Surfaces shall therefore be checked following each de-/-anti-icing operation, in order to ensure that the frozen deposits have in fact been removed. 11. Significant deposits of clear ice can form in the vicinity of the fuel tanks, on wing upper surfaces as well as underwing. Aircraft are most vulnerable in regard to this type of build-up when:
Wing temperatures remain well below zero during the turnround/transit.
Ambient temperatures between -2°C and +10°C are experienced,
There is/has been precipitation.
Clear ice is extremely difficult to detect. Therefore, in the above conditions, or when there is any possibility that clear ice may have formed, a close inspection of upper wing surfaces must be made, using suitable means of access. Should de-/anti-icing be required, a further close inspection must subsequently be made, in order to ensure that all frozen deposits have in fact been removed. Note: The low wing temperatures associated with this type of build-up normally occur when large quantities of cold fuel remain in wing tanks during the turnround/transit and any subsequent fuel uplift is insufficient to cause a significant increase in fuel temperature. 16. Be aware of the 'no spray' areas defined at the end of this manual on the following aircraft diagrams and ensure that these requirements are met, during all de-icing and anti-icing operations. The importance of cleaning the leading edges of the wings and tail was mentioned earlier. However, lowering slats and flaps exposes new surfaces and leading edges where contamination can adhere. If slats and flaps are in a lowered position while the aircraft is on the ground such areas shall be checked and cleaned/protected if necessary. Contamination on these parts will cause irregular airflow and manoeuvrability problems when they are lowered in flight. The fuselage is not a critical lifting surface, but contamination shall be removed in the same manner as other surfaces. The main concern is that snow, slush or ice will break off and damage the engine or aircraft that can cause a dangerous situation during take-off. Frost may be allowed to a certain extent depending on aircraft manufacturer`s requirements and company procedures. The upper surfaces of the wings and tail are not only area to check and treat. The lower surfaces are also highlyimportant. The wing lower surfaces shall be free of ice, but frost may be allowed in some areas (usualtank area) depending on aircraft manufacturer`s requirements and company procedures. However, the horizontal stabilizer lower surfaces shall be clean in all cases. The horizontal stabilizer creates a lifting force either up or down depending on how the elevator (and tabs) is positioned. This tail force is pronounced during take-off and therefore be verified on both side.
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De/Anti-Icing of Aircraft on Ground Manual
13. Safety precautions and Emergency requirements. 13.1.
Safety precautions.
Safety is a subject concerning everyone involved in De-icing Operation . Operational Safety, Equipment Safety, Flight Safety and Health are elements that need to be checked and verified for proper procedures. Many companies and airlines have their own manuals regarding this subject and they should be followed. The Airport Authority may dictate general rules of conduct in emergency situations from an airport of view and by the Operator from a company point of view. Airport equipment needs to be qualified for every specific task accordingly and personnel using them shall have the proper training and qualification for its use. Airport is planned for aircraft operations, but there has to be a large amount of Ground Service Equipment to fulfil all the tasks needed for efficient and safe operation. All these actions on the ground can lead to many incidents and accidents and procedural training should be performed for the whole ground staff for each particular task and for apron operation in general.
13.2.
Equipment safety precautions.
De-icing vehicle contains many areas where safety precautions must be noted. Some of these areas to be noted are the use of hot fluids, the high pressure of the spray, large and heavy vehicles moving around the aircraft, precautions when filling the vehicle, precautions when using the boom and manoeuvring, communication between the sprayer (operator) and driver. At the time of poor visibility while spraying, the use of safety harnesses among other thing.The use of vehicle should be performed in a manner that the following user can continue without any doubts of the safe performance of the vehicle. Any discrepancies shall be informed and noted, and measures shall be taken to indicate to other users that the vehicle may not be usable or that the use is limited. Note thet the vehicle is usually used in areas where space is limited, where visibility can be limited and where the surface is slippery due to ice or the mix of glycol on the ground. It is recommended to test the brakes before approaching the aircraft to verify, how the surface is slipperyt, and to test the performance of the brakes in general.
13.3.
Emergency requirements for De-icing equipment.
A certain amount of emergency solutions are mandatory for a de-icing vehicle to make sure, that some particular situations can be solved or prevented. The emergency system must contain an emergency stop/emergency shut off system at the key points around and inside the vehicle, an emergency lowering system of the boom, a fire extinguisher and a system to prevent any over-heating, overfilling and overpressure in the de-icing fluid system. A way of communication must be in place in order to be able to solve situations with person in the basket/cabin.The operation and monitoring of these systems shall be included in the training and each different vehicle requires similar type training. Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
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De/Anti-Icing of Aircraft on Ground Manual
13.4.
Limitations in operational use of equipment.
There are some limitations on the use of the de-icing vehicles. These limitations refer, among others, to the maximum wind velocity with the boom/basket elevated (variable for each vehicle, can vary between 10-25 m/sec), to the operational speed of vehicle movement around the aircraft during de-icing or anti-icing procedure (not more than 6 km/h), to the movement velocity of the boom, load capacity of the basket/cabin, spray pressure and temperature of heated fluid. These particular limitations and requirements usually published in the current de-icing vehicle standards and manufacturer`s publications. The vehicle also need labeling at all appropriate areas, such as hoses, fluid tanks, filling ports, instructional plates, sprayer guns/nozzles etc. Labeling of these points are important so no confusion would exist when performing de-icing or anti-icing respectively. Since some Operators use uncolored de-icing and anti-icing fluids, this aspect is even more important.
13.5.
Equipment communication requirements.
De-icing vehicle needs to have an appropriate communication system that is suited for the operation in use (VHF, UHF radio, mobile phones etc.). a two-way communication needs to be established between the vehicle and the aircraft or the coordinator. This communication needs to be performed via VHF-radio. The radio needs to be approved for use for aviation frequencies. An intercom communication (or similar) needs to be established when two persons are operating the vehicle. The external noise disrurbs (e.g. aircraft running engines) when using a headset type communication in open basket. External noise can disrupt the communication and care should be taken so, as not to continue de-icing operation with misleading or no communication at all. When two or more vehicles are de-icing aircraft, other communication possibilities may be considered between these vehicles. Communication b/w vehicles is needed in order to verify proper treatment of aircraft and de-icing procedures. This chain of comm. Depends on how the particular winter operation is planned and performed. Some use coordinator or team leader for all the communication between the aircraft while others perform the comm. from each vehicle.
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De/Anti-Icing of Aircraft on Ground Manual
14. Holdover Time. Holdover times are provided to assist:
1. Ground Staff in providing the operating Captain with an aircraft in a fully de-/anti-iced condition. 2. The operating Captain in carrying out his responsibility for ensuring that the aircraft remains free of contamination until take-off. Where appropriate, they should be used in conjunction with a visual pre-take-off check of the wing, in order to ensure compliance with the 'clean aircraft' concept. The judgement and experience of the Captain will be required to assess the nature and rate of precipitation and the holdover time applicable to the actual conditions. Holdover time is obtained by de-/-anti-icing fluids remaining on and protecting aircraft surfaces for a period of time. With a one-step de-/-anti-icing operation holdover begins at the start of the operation and with a two-step, at the start of the second (anti-icing) step. Holdover time will have effectively run out when frozen deposits start to form/accumulate on aircraft surfaces. ISO Type I fluid forms a thin liquid wetting film which rapidly flows off the aircraft surfaces, giving a more limited holdover time than Type II/III/IV fluids. With this type of fluid no additional holdover would be provided by increasing the concentration of fluid in the fluid/water mix. ISO Type II, III and Type IV fluids contain a pseudo-plastic thickening agent, which enables these fluids to form a thicker liquid wetting film, enabling the fluid to remain on and protect aircraft surfaces for significantly longer than Type I fluids. With these types of fluid additional holdover time will be provided by increasing the concentration of fluid in the fluid/water mix, with maximum holdover available from the undiluted fluid. The tables published in both ATP688/2 and the Aircraft Flying Manuals give an approximate indication of the holdover times that could reasonably be expected during freezing precipitation. Many variables can influence holdover and these times should therefore not be considered as absolute. The actual time of protection may be extended or reduced, depending upon the ambient conditions. The lower limit of the published time span approximates to the estimated time of protection during heavy precipitation and the upper limit to the estimated time of protection during light precipitation. Following application of Type II, III or Type IV fluids a viscous fluid film isformed which, in the absence of precipitation, will remain on aircraft surfaces for an extended period of time. Thus, on those occasions when an aircraft has been de-/-anti-iced in anticipation of freezing precipitation, the holdover time should not be considered as having started until precipitation is present. Likewise, in conditions of intermittent precipitation holdover time may effectively be suspended during periods when no precipitation is present. The holdover times can also be extended by visual inspection at any time. These times are not absolute but cumulative, for example the following three cases are all permissible: - Weather Conditions: temperature from 0°C to -3°C; - Anti-icing fluid (Type/Mix): ISO Type IV (75/25%); - Published Holdover Time: 20-35 minutes. Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
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De/Anti-Icing of Aircraft on Ground Manual
OAT (°C)
Fluid/Mix
Frost
Freezing fog
Snow
Frz. Drizzle
Frz.Rain
0 to -3
75/25%
5:00
1:05-2:00
0:20-0:35
0:30-1:00
0:15-0:30
Case 1:
Heavy snow for 20 minutes or light to moderate snow for 35 minutes.
Case 2:
Light to moderate snow for 15 minutes, which then stops, followed later by two more separate 10 minute periods of light to moderate snow.
Case 3:
35 minutes of light to moderate snow, which then stops permanently.
There will be no requirement for further de-/-anti-icing, provided there is no evidence of frozen contamination on the surface of the wing, or likelihood of further freezing precipitation, before the start of the take-off roll. The mechanism by which precipitation degrades the antiicing fluid is to dilute it over a period of time. Clearly, if there is no precipitation for a time, the mechanism of dilution effectively ceases for that period. Should severe conditions be experienced, or the published holdover times have either been exceeded or are about to expire, a further visual check of the wing should be made just prior to take-off, to ensure that no frozen deposits are in evidence. Only when such deposits are present will it be necessary for the de-/-anti-icing operation to be repeated.
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De/Anti-Icing of Aircraft on Ground Manual
15.0. De-/-anti-icing fluid Application and Limitations. 15.1.ISO Type I fIuids. The freezing point of the ISO Type I fluid used for either one-step de-/-anti-icing or as the second step in a two-step operation shall be at least 10°C below the ambient temperature. The freezing point of the ISO Type I fluid mixture used for the first step in a two-step operation shall not be more than 3°C above the ambient temperature.
15.2. ISO Type II and Type IV fluids. Approved concentrations of ISO Type II and Type IV fluids, used either for one-step de-/anti-icing or as the second step in a two-step operation, are listed below, together with details of the lowest temperatures at which the various concentrations may be applied to aircraft surfaces :
*ADF/AAF ULTRA + in concentrate form (100%) is limited to a lower application temperature limit of -24°C, based on aerodynamic performance.
Approved concentrations of ISO Type II and Type IV fluids, used for the first step in a two-step operation, are listed below, together with details of the lowest temperatures at which the various concentrations may be applied to aircraft surfaces :
Upper wing skin temperatures may, under certain circumstances, be lower than OAT. When this is suspected, e.g. when large quantities of 'cold' fuel remain from the previous sector, consideration should be given to selecting a stronger mix than would be required by the existing OAT. This will ensure that an adequate buffer is maintained between the freezing point of the fluid used and the temperature of the upper wing surface. Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
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De/Anti-Icing of Aircraft on Ground Manual
15.3.
Summary Limitations.
The use of undiluted (100 %) and 75 % Type II or Type IV fluids are limited to aircraft with rotation-speed lower than 85 knots. It is concerning for most propeller aircrafts. For example, “Fokker-50” has rotation speed about 90 knots. Undiluted Type II or Type IV fluids must not be applied on fuselage forward of overwings exits. Never heat undiluted Type II/IV fluids continuously above +70°C. (The maximum continuati-on in this condition is 30 days in closed tanks). The aircraft/component surface temperature must not exceed +85° C during de-icing with hot fluid or air. It means that fluid must never be heated more than +85°C . Fluid used for the First step in Two-step De-/-Anti-icing procedure shall have a freezing point maximum 3° C above OAT. the Anti-icing step (second step) shall be perfomed before fluid of First Step freezes, usually within 3 min , depending of weather conditions. Type I fluid used for One-step De-icing or Anti-icing, or as the Second step fluid in Two-step procedure must have a freezing point of at least 10° C below actual OAT. For underwing De-/-Anti-icing with Type I fluid a minimum 5°C freezing point buffer may be used. As fluid freezing may occur, Type II/IV mixture 50/50 % is not permitted for antiicing of cold soaked wings (shown by frost or ice on the fuel tank surface). Mixing of different types or manufacturer`s fluids is NOT PERMITTED.
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De/Anti-Icing of Aircraft on Ground Manual
16.0. Check of fluid concentrations.
"In order to ensure that the concentration of each batch of de-/anti-icing fluid is correct, a refractive index check shall be made prior to use. For operational purposes, the concentration of the fluid used shall not be less than the declared value nor more than +5% above it."
The concentration of aircraft de-/-anti-icing fluids is checked with a refractometer, calibrated to read refractive index. Using either a graph or table supplied by the fluid manufacturer, the percentage of de-/-anti-icing fluid in the fluid/water mix can be determined. To avoid variations due to temperature, samples should be checked in an area where the ambient temperature is approximately 20°C.
Refractometer
Approved refractometers are calibrated in the range 1.330 to 1.440 and will have been supplied through OGED. These precision instruments are sealed for life and will not need adjustment/re-calibration, unless they have been subjected to significant damage, such as being dropped onto a hard surface. When taking samples for refractive checks, it is important to ensure that they are representative of the fluid being tested. That is when sampling is taken from the nozzle.
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De/Anti-Icing of Aircraft on Ground Manual Pocket Refractometer Operating Instructions: Prior to use check the general condition of the unit, in order to ensure that it has not previously been damaged. Should there be any indication of possible damage, follow the procedure detailed below, but instead of de-/-anti-icing fluid, place one or two drops of distilled or demineralised water onto the prism. A reading of 1.333 should be obtained, however, where a different result is evident, the instrument must be re-calibrated 1.
Using a moistened soft cloth or soft tissue, lift the cover plate and carefully wipe the surface of the prism and underside of cover plate, immediately drying the surfaces with a dry soft cloth or soft tissue.
2. Ensure that the temperature of the instrument is approximately 20°C (generally if the instrument has been stored in a heated office/workshop, or even in a trouser or jacket pocket for a period of time, it will invariably be in the region of 20°C). 3. holding the instrument in a horizontal position lift the cover plate, drop one or two drops of the fluid to be checked onto the prism and close the cover plate. Note:
4.
Where hot fluid is to be tested, first allow the temperature to drop to approximately 20° C, before placing on the prism. Where the temperature of the sample is low, allow it to increase to around 20°C, before testing.
Looking into the eye piece, point the refractometer at a suitable light source.
5.
Carefully adjust the eye piece by twisting it and gently pulling it out/pushing it in, until the scale comes into focus.
6.
Continue pointing the refractometer at the selected light source and a dark line or shadow should be observed crossing the scale at some point.
7.
Take the reading where the line crosses the scale (each of the small graduations equates to 0.001) and write down the result.
8.
Using a graph or chart supplied by the fluid manufacturer for the specific fluid being tested, read off the percentage of de-/anti-icing fluid in the sample.
9.
Ensure that the fluid is within the limits defined above, before approving for use.
10. Using a moistened soft cloth or soft tissue, lift the cover plate, carefully wipe off the residues and immediately dry the surfaces with a dry soft cloth or soft tissue.
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De/Anti-Icing of Aircraft on Ground Manual
17. Post De-/-Anti-cing Checks before a/c depature. Immediately prior to departure the Engineer, or suitably trained and approved person* (split between the De-icing Operative/Lead Operative and Headset Operative) releasing the aircraft will ensure the aircraft is prepared for flight in accordance with the requirements detailed in ATP 688/2 and the appropriate Aircraft Maintenance Manual.
It is a mandatory requirement that the critical aircraft surfaces are free of frozen deposits, as defined below: 1. Wings, Tail and Control Surfaces – shall be free of all forms of frost, ice, slush and snow (a coating of frost up to 3 mm is allowed on underwing surfaces, provided it is within defined limits). 2. Fuselage - shall be free of slush, ice, snow and any deposits of frost that may be outside defined limits. 3. Pitot Heads, Static Ports, Airstream Direction Detector Probes, Angle of Attack Sensors – shall be free of frost, ice, slush, snow and fluid residues. 4. Engine Inlets - shall be free of internal ice, slush and snow and the fan shall be free to rotate. Ensure engine fan blades rotate freely. Serious engine damage may occur if ater from melting ice/snow subsequently re-freezes, bonding the fan blades to the lower casing. 5. Air Conditioning Inlets and Outlets – shall be free of frost, ice, slush and snow. Outflow valves shall be clear and unobstructed. 6. Landing Gear, Landing Gear Doors and Wheel Bays - shall be unobstructed and free of frost, ice, slush and snow.
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De/Anti-Icing of Aircraft on Ground Manual 5 Fuel Tank Vents - shall be free of frost, ice, slush and snow.
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De/Anti-Icing of Aircraft on Ground Manual A functional flight control check, using an external observer, may be required after de-/-anti-icing, depending upon aircraft type (see relevant manuals). This is particularly importan in the case of an aircraft that has been subjected to an extreme covering of ice or snow. * Where no Approved Engineer will be present at the De-/-anti-icing area to: 1. Check that appropriate surfaces are free of frozen deposits on completion of de-/anti-icing. 2. Pass the appropriate Anti-icing Code to the operating Captain. Ground OPS / OGKT shall ensure that the above responsibilities are delegated to a competent local official or officials, who have been trained and approved in regard to 'Cold Weather Operations'. Written authority for these functions has to be provided. ========================================================
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De/Anti-Icing of Aircraft on Ground Manual
18.0. Anti-icing codes and communication procedures. 18.1.Anti-icing codes reporting. When approved fluids are used to remove frozen deposits from the surfaces of an aircraft, the anti-icing capability of the fluid will protect the 'clean' surfaces against further accumulations of frost, ice, slush and snow for a period of time.This Holdover Time will be dependent on the actual weather conditions, the type of fluid used and in the case of ISO Type II and Type IV fluids, the mixture strength. To enable Flight Crew to determine the likely holdover time, in regard to the treatment applied to their aircraft, a number of simple Anti-icing Codes have been devised. The appropriate code will be entered into the Tech. Log and describes the fluid type / concentration, the local time when the final de-/-anti-icing step was started and the date. When an aircraft is de-/-anti-iced immediately prior to departure, the Headset Operative will inform Flight Crew of the Anti-icing Code via the intercom. Where 'Off Stand' de-/-antiicing is carried out the Anti-icing Code will be passed to Flight Crew verbally and the details recorded locally in a journal or on a secure system.
The Anti-icing Code consists of four elements: ELEMENT 'A':
Specifies fluid type (e.g. Type I, Type II, or Type IV).
ELEMENT 'B':
Specifies the concentration of fluid within the fluid/water mix, expressed as a percentage by volume, (e.g.75 = 75% fluid, 25% * Not required for Type I fluid.
water). ELEMENT `C: 13:30).
Specify in local time when the final step was started (e.g.
ELEMENT 'D':
Specify date (e.g. 20APR2009).
Examples : TYPE II/75/0630/08DEC2009. TYPE 1/0827/11FEB2009. TYPE IV/100/1130/25DEC2009.
Used in conjunction with the Holdover Time charts, these codes will allow Flight Crew to estimate the holdover that may be expected, under the prevailing weather conditions. The code also acts as confirmation that appropriate surfaces are free of all forms of frost, ice, slush and snow, at the time of receipt. Note: when a two-step de-/-anti-icing operation has been carried out, the Antiicing Code is determined by the second step fluid. 17.2. De-icing/anti-icing communication. The Anti-icing code contains the minimum information needed for communication. It is allowed, and preferred, to give other information, such as areas treated, areas checked, engines and propellers, frost thickness on underwings etc., if there is a need for it or the crew has requested something else. The way of communication can vary with local settings and Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
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De/Anti-Icing of Aircraft on Ground Manual arrangements. There can be VHF- or UHF-radio, headset/intercom at the aircraft, team leader communication, de-icing vehicle and coordinator communication with the aircraft. The way of providing the information to the crew is not relevant, it is, however, important what and how communication is performed. Proper communication is as important as proper de-/-anti-icing. There cannot be any doubt of the procedure, fluid used, holdover time, areas covered etc., when communicating and veriying process. As a rule, an aircraft shall be dispatched for depature after a de-/-antiicing operation until the flight crew has been notified of the type of the de-icing/anti-icing performed. The standardised notification performed by qualified personnel indicates that aircraft critical parts are checked free of ice, frost, snow and slush, and in addition includes the necessary Anti-icing Code, as specified, to allow the Flight Crew to estimate the holdover time to be expected under the prevailing weather conditions. As important as the communication between the flight crew and the de-icing crew so is the communi-cation between de-icing crew themselves and the de-icing coordinator. No misconception can be allowedwhen de-icing on treatment and verifying operational procedures. If several de-icing vehicles are performing the de-/-anti-icing simultaneously on an aircraft, a Leader of De-icing Team should be decided. This team leader will be the person communicating with the aircraft and vehicle at the aircraft. The procedures and areas to be treated are divided and settled according to the leader instructions. This procedure will increase the safety of proper communication and perations. The team leader will give instructions on fluids and mixturesto use, areas to be treated and by whom etc. after the procedure is done; all vehicles report to the team leader their particular information. The team leader will conclude which area treated first with anti-icing fluid and report this time to the flight crew along with the rest of the required information (anti-icing code). At the time of final report, all vehicles shall be in a safety area or in a position well clear of the aircraft. This procedure should reflect the local demands.
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De/Anti-Icing of Aircraft on Ground Manual
19.0. Fluid handling and storage requirements. 19.1.
Fluid handling.
Current Type II and Type IV fluids are chemically 'thickened' in order to induce pseudoplastic behaviour. In simple terms this means that the fluid remaining on aircraft surfaces after either de-icing or anti-icing will have a relatively high viscosity, enabling it to remain on and protect the critical surfaces for a period of time. However, during the take-off roll the increasing speed of the airflow over the surfaces of the wing will effectively 'shear' the fluid, significantly reducing its viscosity and thus allowing it to flow off. The major requirements of such a fluid are, to some extent, in conflict in that they must be viscous enough to allow them to remain on and protect aircraft surfaces from freezing precipitation until take-off and yet of a low enough viscosity to enable them to flow off during the take-off roll to provide aerodynamically clean wings at rotation. In order to satisfy these conflicting requirements it is important that the fluids remain in good condition until take-off. Should the viscosity be too low, the published holdover times will not be achievable, too high and fluid residues, which could subsequently affect the aerodynamic performance of the aircraft, will remain on the wing surfaces, even after take-off. It has previously been determined that careful handling is required at the pre-aircraft stage, in order to ensure that the fluids are not degraded, either prior to or during application. The methods employed to store, transport, heat, pump and apply these fluids must be in line with the manufacturers recommen-dations, if the fluid is to be maintained in an acceptable condition from delivery to take-off. The basic effect of this type of degradation is to reduce the viscosity of the fluid, thereby allowing it to flow off prematurely. This leaves the external surfaces of the aircraft unprotected and therefore vulnerable to the effects of freezing precipitation. Under these conditions the published holdover times may NOT be achievable. In order to avoid degrading Type II and Type IV fluids to an unacceptable degree, it is important that the advice/approval of the fluid manufacturer be follow, before purchasing new, or modifying existing, vehicles and equipment. When de-/-anti-icing fluids are heated, they shall be heated in accordance with fluid manufacturer’s guidelines. As a general rule, a temperature between+60-80°C is desired for for de-icing purposes. Caution:
never heat undiluted Type II/IV fluids continuously above 70°C . (Maximum 30 days in closed tank).
19.2. Storage requirements. Storing: relevant tanks, piping and equipment shall be purged and cleaned before being initially filled, after maintenance, or whenever changing Type II or Type IV fluids. The storage tanks and tanks in De-/-anti-icing vehicles shall be inspected annually for corrosion and contamination. Stainless steel tanks shall be inspected for corrosion every 5 years. The inspection should be carried out in the summer period. If corrosion or contamination is evident, the tanks shall be repaired / cleaned or replaced. Latest inspection date should be at the tank or responsible department or company shall have inspection records available for proof of this inspection. Labeling: to avid mixing and contamination the tanks shall be clearly labeled with fluid type and actual vendor designation. Further, all fill ports and discharges points shall be clearly labeled with with fluid type prevent contamination by other fluids. Labels shall be made of weather and wear resistant material and installed permanently. Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
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20.0. Clear ice and Rain on Cold Soaked Wing. 20.1. Formation of clear ice. When large quantities of “supercooled” fuel remain from the previous sector, significant amounts of clear ice can form on both upper and lower wing surfaces, in the vicinity of the fuel tanks. Aircraft are most vulnerable in regard to this type of build-up when: 1. Wing temperatures remain well below zero during the turnround, transit or nightstop. 2. Ambient temperatures between -2°C and +15°C are experienced. 3. Precipitation occurs while the aircraft is on the ground.
This type of ice formation is extremely difficult to detect, therefore, when the above conditions prevail, or when there is otherwise any doubt that clear ice may have formed, a close inspection of the wing upper surface must be made, using a suitable means of access. Should de-icing be found to be required, a further close inspection must be made immediately prior to departure, in order to ensure that all frozen deposits have been removed. The low wing temperatures associated with this type of build-up, normally only occur when large quantities of cold fuel remain in wing tank during the turnround/transit and any subsequent fuel uplift is insufficient to cause a significant increase in fuel temperature.
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20.2.Clear ice Checks and precautions. Clear ice can form on aircraft services, below a layer of snow or slush. It is therefore important that surfaces are closely examined follwing each de-icing operation, in order to ensure that all deposits have been removed. Significant deposits of clear ice can form in the vicinity of the fuel tanks, on wing upper surfaces as well as under-wing. This type of ice formation is extremely difficult to detect. Therefore when the conditions prevail, or when there is otherwise any doubt whether clear ice has formed, a close examination shall be made immediately prior to depature, in order to ensure that all frozen deposits have in fact been removed. Note that this type of build-up normally occurs at low wing temperatures and when large quantities of cold fuel remain in wing tanks during the turnaround/transit and subsewuent re-fueling is insufficient to cause a significant increase in fuel temperature.this does not rule out the possibility of ice formation in any other conditions.finding clear ice, and removing it, should always be noted to the flight crew. Frost on the underside of wings and humidity is a good sign that there may be ice formation on the upper surfaces, but note that it is not single way to determine ice formation.
20.3. Local Frost Prevention in Cold Soaked Wing Areas Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
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Wing surface temperatures can be considerably below ambient due to contact with cold fuel and/or close proximity to large masses of cold soaked metal. In these areas frost can build up on wing surfaces and may result in the entire wing being de-iced/anti-iced prior to the subsequent departure. This procedure provides recommendations for the prevention of local frost formation in cold soaked wing tank areas during transit stops in order to make de-icing/anti-icing of the entire wings unnecessary under such circumstances. This procedure does, however, not supersede standard de-icing/antiicing procedures and has to fulfil the requirements of section 9.0. This procedure also does not relieve from any requirements for treatment and inspections in accordance with aircraft manufacturer manuals.
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De/Anti-Icing of Aircraft on Ground Manual 20.3.1 Definitions Local frost build-up: Limited formation of frost in local wing areas sub-cooled by cold: fuel or large masses of cold metal; this type of frost does not cover the entire wing !
20.3.2 e
Procedur
Using suitable spray equipment, apply a proper coating of undiluted type II or IV anti-icing fluid on the wings in the limited cold soaked areas where formation of frost may be expected due to contact of the wing skin with sub cooled fuel or masses of cold metal. A proper coating completely covers the treated area with visible fluid. NOTE: For limitations see paragraph 20.3.3.
20.3.3 Limits and Precautions This Local Frost Prevention procedure does not substitute standard deicing/anti-icing procedures in accordance with section 9, clear ice checks or any other aircraft manufacturer requirements, nor the requirement that aircraft surfaces are clear of frost, slush, snow and ice accumulation. • This Local Frost Prevention Procedure shall only be carried out if approved by the operator of the aircraft to be treated, and it shall only be carried out by properly qualified and trained personnel. : This Local Frost Prevention procedure shall be applied on clean wings immediately following arrival of the aircraft. Application is acceptable at the latest when frost just starts to build up, but in this case the fluid shall be applied at a minimum temperature of 50- °C. If precipitation occurred between application of the fluid and dispatch of the aircraft and / or if precipitation is expected before take-off, a standard two-step de-icing/anti-icing treatment shall be performed in accordance with Section 9.0. Both wings shall receive the same and symmetrical treatment, i.e. the same area in the same location shall be sprayed, also when conditions would not require the treatment of both wings. CAUTION: Aerodynamic problems could result if this requirement is not met. A holdover time shall not be assigned to a Local Frost Prevention treatment since the treatment does not cover the entire aircraft or wing surface respectively.
20.3.3
FINAL CHECK
A tactile check (by touch) of the treated areas and a visual check of the untreated areas of both wings shall be performed immediately before the aircraft leaves the parking position. These checks are conducted to ensure that both wings are clean and free of frost. The applied de-/-anti-icing fluid shall still be liquid and shall show no indication of failure, such as colour turning to white, loss of gloss, getting viscous, showing ice crystals. 20.3.4
Flight Crew information: Follwing information shall be provided to the Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
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De/Anti-Icing of Aircraft on Ground Manual Flight Crew: “Local frost prevention was accomplished”.
21.0. Environment. 21.1.Airport layout and environment considerations. De-icng and anti-icing fluids are the chemical products with environment impact. De-icing fluids are not the only chemical used at airports and by far not the most hazardous.even so; care should be taken whenever using de-icing fluids. Some airports have restricted he use of de-icing fluids at some areas, whereas at some other airports system of drainage covers the majority of the airport area. Glycol is a biodegradable fluid, but when in contact with ground water it uses a lot of oxygen, which has an impact on environment. Fluids are also, at times, used in large quantities and this can have a “peak” impact on the environment. Airports can be located near the lakes, rivers over ground water and this in turn sets strict requirements on how wastewater/stormwater is sprayed, collected, contained and treated. The size of the airport or airlines using the airport facilities will have an effect on the quantities of de-icing fluids used (assumed that the airport is in general a winter operation airport). Airports usually provide the fluid collection equipment, but some de-cing operators may also be responsible for this procedure. Sprayed fluid/waist water is not the issue, also contaminated snow must be taken into account and collected in a place where the snow can melt and be taken care off. Aircraft de-icing fluids are not the only de-icing fluids that are sprayed, also apron de-icing fluids, for example, acetates are used used extensively and has similar environment impact as aircraft de-icing fluids. The airport infrastructure, and how it is operated, has a major role in environment issues. Aircraft may be de-iced at the gate or at a remote area, but the waist glycol needs to be collected according to a predetermined plan. Aircraft deicing fluids will run off the wing all the way from the gate and taxiway to the runway and take-off (where the majority of fluid left on the surfaces is drained off). The whole chain must be considered and not only at the time of de-icing. The de-icing crew has no control on other issues than what is relevant for the actual de-icing or anti-icing work. Issues like : taking samples, testing the spray nozzle or other tests, place on the apron, where the aircraft are sprayed, can be controlled by the de-icing crew and should be performed according to known and accepted procedures.
21.2.Glycol identification and environment impact. During fluid handling avoid any unnecessary spillage and comply with local environment and health laws and refer to the manufacturer’s safety data sheet. Even if the de-icing operation is performed in a defined area, collected snow and fluid drained from aircraft while it taxiing or during take-off may find their way into the ground water. Approximately 1 gr of glycol consumes 0, 8-1, 3 gr of oxygen in water. The degradation of glycol in the water can take from one day to a week depending on the amount of glycol and the time period when de-icing fluid is used extensively. The de-icing operation can not be limited on how much fluid is consumed, as this is dependent on weather and aircraft contamination. There is a specific margin on minimum fluid used (1 liter/m² on aircraft surface area), that is recommended and this shall not be compromised. However, the technique of spraying and removing contamination should be Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
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De/Anti-Icing of Aircraft on Ground Manual well trained and adapted, which will minimize any excess consumption of fluid. There are other issues that can limit the use of glycol, such as the use of forced air, using propeller/wing covers, infrared technology, manual removal of snow by brushes and brooms, storing aircraft in hangars etc. Some airlines also approve using of hot water for de-icing, if temperature andregions where it is possible without freezing though limit this. Even if the glycol (ethylene and propylene) is considered fairly non-toxic to the aquatic environment, the use should be limited and well estimated whenever possible. The use of glycol in large quantities can have a serious impact on fish and wild life, if drained into the water. There should be a good dialogue between the de-icing Operator and the Airport in order to improve related issues. The drainage should be organized by the he airport with winter operations in mind and the de-icing operator should limit spillage by proper training and with defined procedures.
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22.0. New procedures and development, lessons learned from previous winters.
1) From September 2009 already existing 24-th Edition of “Recommendations for De-icing and Anti-icing of aircraft on the Ground ”. 2) Expirence of last winter show, that manual removal from aircraft surfaces of snow and slush reduce amount of de-icing fluid and time for complete de-icing of aircraft.
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23.0. Personnel Health and Safety. Safety is a subject concerning everyone involved in De-icing Operation. Operational Safety, Equipment Safety, Flight Safety and Health are elements that need to be checked and verified for proper procedures. Many companies and airlines have their own manuals regarding this subject and they should be followed.
23.1.Influence of de-/-anti-icing fluids. Many different de-icing and anti-icing fluids are in use around the world. There are several fluid manufacturers that can provide certified fluids for the market. The composition of the fluid varies by region and by manufacturers and also depending on the use of the glycol (aircraft de-icing and ant-icing fluids or apron, taxiways and runways de-icers). Some compounds that can be found in use at airports and operators are propylene-, ethyleneand di-ethylene glycol, urea, potassium, acetate, calcium magnesium acetate, sodium formate, chlorides and isopropyl alcohol. Propylene- and ethylene glycol are perhaps the most common in use and known for aircraft de-/-anti-icing. For aircraft de-icing and antiicing operations Type I, Type II, Type III and Type IV fluids are used to identify different glycol and their specific application. These fluids are diluted to some extent with water. Additives are used in the fluid to make it serve a specific task. Even, if glycols are found to have low toxity, proper precautions should be taken. Pure glycols have been tested ant results concluded, but additives are considered a trade secret, so all aspects have not been tested when it comes to aircraft de-/-anti-icing fluids. Ethylene-/propylene glycol compounds are found/used among others in food, make-up products, paints, lacquer, automotive antifreeze etc. Their irritation and vapours has not been found to be toxic. Orak ingestion is in general toxic for ethylene glycol, but propylene glycol has not been found to be toxic, but with large quantities it can reach a dangerous level. In normal operation use ingesting glycol orally should not be possible (excluding some drops from splashing). Consult the specific material safety data sheet received from the fluid, manufacturer to proper safety procedures.
23.2.Personal Health and Safety. De-icing operations is many times subjected to harsh elements. There are cold temperatures, wind, some sort of precipitation, loud noises from aircraft engines/APU, jet blast, marginal sunlight and airport lighting at winter time, manoeuvring a large of deicing vehicle in narrow areas between aircraft de-icing spraying itself. Despite all of these items the de-icing operation can be performed safety and efficiently with the proper training, equipment and safety gear. De-cing vehicles are basically divided into openbasket and closed-basket de-icers. A closed basket protects the de-icers from many of the mentioned elements, but if there are procedures performed outside the vehicle, proper safety gear should be used. When de-icing from an open-basket the de-icer is also subjected to glycol mist (among the rest mentioned earlier) while spraying and proper protective clothes and gear should be used. Rubber gloves, water proof clothing, water proof shoes (proper footwear), heating protector and safety harness are items that should be used for sufficient protection under such conditions. Sufficient washing of hands, neck and face (any areas subjected to Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
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De/Anti-Icing of Aircraft on Ground Manual outside elements) should be remembered in order to minimize any possible skin irritation caused be glycols. Hearing protectors are very important, because of the high amount of noise at the apron. Noises between 80-100 decibel are quite ordinary, but even 120 decibel can experienced at times. The noise experienced over time (work period) should also be considered.
24.0 Quality Assurance Programme 24.1. Fluid Sampling Procedure for Type II, III, or Type IV Fluids. 24.1.1.
Introduction
To ensure that the necessary safety margins are maintained between the start of the deicing/anti-icing operation and takeoff, the fluid used to both de-ice and anti-ice aircraft surfaces, must be in an "ex-fluid manufacturers" condition and at the correct concentration. Due to the possible effect of vehicle/equipment heating and/or delivery system components on fluid condition; it is necessary for the sampling method to simulate typical aircraft application. This section therefore describes the approved methods for collecting samples of Type: II, III, and IV | fluids, sprayed from operational aircraft de-icing/anti-icing vehicles/equipment, prior to the necessary quality control checks (see section 6.3) being carried out. 24.1.2. Method The application is made onto a clean polythene sheet (approx. 2m x 2m) laid directly on the ground, or onto an aluminium plate with associated recovery system. Depending on wind speed/direction at the time of sampling the polythene sheet may require to be weighted down at the edges, to prevent movement. The distance between the spray nozzle and the surface shall be approximately 3m and the fluid shall be sprayed perpendicular to the surface. Where different spray patterns and flow rates are used during routine de-icing/anti-icing operations, samples shall be taken at typical nozzle settings (e.g. fine, medium or coarse): and flow rates for anti-icing. 24.1.3.
Procedure
a) Select the required flow rate/spray pattern for the fluid to be sampled. b) Spray the fluid to purge the lines and check the concentration of a sample, taken from the gun/nozzle after purging. c) Should the refractive index indicate that the lines have not been adequately purged, repeat previous item “ b) “until the concentration is correct for the fluid to be sampled (on certain vehicles it may be necessary to spray more than 50 ltrs of fluid, before the lines are completely purged). d) Direct the fluid onto the sampling surface and spray an adequate amount of fluid to allow for a, sample to be taken. e) Where a polythene sheet is used for sampling purposes, carefully lift the corners of the sheet and collect f)
of the fluid in a clean and dry bottle. Attach a label to each sample-bottle, providing the following data: Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
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De/Anti-Icing of Aircraft on Ground Manual i.Brand name and type of fluid (e.g. Clariant MPII Flight/Type II) ii.Identification of the vehicle (e.g. Elephant Beta No.04) iii.Source where the sample was taken from (e.g. nozzle or vehicle tank) iv.Mixture ratio (100/0, 75/25 or 50/50) v.Station (e.g. HRK etc.) vi.Date sample was taken Caution: never use a beverage-bottle!
24.2. Checking Procedure for Aircraft De-/Anti-icing Fluids. 24.2.1. Introduction This checking procedure for aircraft de-icing/anti-icing fluids is in compliance with AEA station quality assurance programme for aircraft de-icing/anti-icing operations and with the relevant sections of JAR OPS 1.345. The procedure ensures that the required safety standards concerningthe de-icing/anti-icing fluids quality are maintained. When discrepancies are found, further investigation has to be conducted prior to use of the fluid. 24.2.2. Delivery Check for Fluids Before filling the tank with the de-icing/anti-icing fluid it shall be established that the brand name and the concentration of the product mentioned in the packing list corresponds to the:brand name and the concentration mentioned in the storage tank. A sample of the delivered product shall be taken and checked from each batch before the storage tank/vehicle is filled. Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
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Perform the delivery check for fluids as follows : Type I fluid : - perform a visual contamination check according to 25.6.6.(1); - perform a refractive index check according to 25.6.6.(2); - perform a pH-value check according to 25.6.6.(3); Type II, type III, and type IV fluids: -
perform a visual contamination check according to 25.6.6.(1); perform a refractive index check according to 25.6.6.(2); perform a pH-value check according to 25.6.6.(3); perform a field viscosity check according to 25.6.6.(4);
24.2.3. Deicing/Anti-icing Vehicle Fluid Checks 1) Concentration Checks Fluids or fluid/water mixture samples shall be taken from the de-icing/anti-icing vehicle nozzles o na daily basis when vehicles are in use. Perform a refractive index check according to 25.6.6.(2). The sample shall also be protected against precipitation. NOTE 1:
Trucks without a mixing system. Samples may be taken from the truck tank instead of at the nozzle. NOTE 2: Trucks with proportional mixing systems. Operational setting for flow and pressure shall be used. Allow the selected fluid concentration to stabilise before taking sample (see also 25.5.3). NOTE 3: Trucks with automated fluid mixture monitoring system. The interval for refractive index checks has to be determined by the handling company in accordance with the system design.
2) Checks on (directly or indirectly) heated Fluids Fluid or fluid/water mixture samples shall be taken from the de-icing/anti-icing vehicle tanks. As a guideline, the interval should not exceed two weeks, but it may be adjusted in accordance with localexperience. Perform a Refractive Index Check in accordance with 6.3.6.2. 24.2.4. Laboratory Checks for Fluids The laboratory checks shall be performed for the fluids at the start and in the middle of the de-icing season and upon request by the airline. Fluid samples shall be taken from all deicing/anti-icing vehicle spray nozzles of all vehicles and from all storage tanks in use. For thickened de-icing/anti-icing fluids take the sample as described in fluid sampling procedure for Type II, Type III, and Type IV fluids (see section 25.5.).
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Perform the laboratory check for fluids as follows : Type I fluid : - perform a visual contamination check according to 25.6.6.(1); - perform a refractive index check according to 25.6.6.(2); - perform a pH-value check according to 25.6.6.(3); Type II, Type III, and Type IV fluids : -
perform a visual contamination check according to 25.6.6.(1); perform a refractive index check according to 25.6.6.(2); perform a pH-value check according to 6.3.6.3 perform a laboratory viscosity check according to 25.6.6.(5) -> Not applicable to samples taken from spray nozzle(s) used for deicing exclusively.
24.2.5. Field Check for Fluids Field check for fluids shall be made always when station inspection is made. The samples shall be taken from the storage tank and from the de-icing/anti-icing equipment nozzle. For thickened de-icing/anti-icing fluids take the sample as described in fluid sampling procedure for Type II, Type III, or Type IV luids (see section 25.5). Perform the field test for fluids as follows : Type I fluid : - perform a visual contamination check according to 25.6.6.(1); - perform a refractive index check according to 25.6.6.(2); - perform a pH-value check according to 25.6.6.(3); Type II, Type III and Type IV fluids : -
perform a visual contamination check according to 25.6.6.(1); perform a refractive index check according to 25.6.6.(2); perform a pH-value check according to 25.6.6.(3); perform a field viscosity check according to 25.6.6.(4);
24.2.6. Fluid Check Methods 1) Visual Contamination Check - put fluid from the sample into a clean glass bottle or equivalent; - check for any kind of contamination (e.g. rust particles, metallic debris, rubber parts,etc.); - the check can be made by any equivalent method.
2) Refractive Index Check - make sure the refractometer is calibrated and clean; - put a fluid drop taken from the sample or from the nozzle onto the test screen of the refractometer and close the prism; ; - read the value on internal scale and use the correction factor given by the manufacturer of the fluid in case the temperature of the refractometer is not 20°C ; - compare the value with the figures from the fluid manufacturer; - clean the refractometer and return it into the protective cover; Phone: 00355 4 2381 600 Fax: 00355 4 2381 545 E-mail: info@tirana-airport.com Website: www.tirana-airport.com
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De/Anti-Icing of Aircraft on Ground Manual - the check can be made by any equivalent method;
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De/Anti-Icing of Aircraft on Ground Manual
3) pH-value Check - take a piece of pH paper and put it in the fluid so that the pH paper becomes wetted with the fluid ; - remove the pH paper from the fluid and compare its colour with the colour of the table provided with the pH paper and read the corresponding pH value; - compare the pH-value with the figures from the fluid manufacturer ; - the check can be made by any equivalent method;
4) Field Viscosity Check - this check shall be made with a falling ball method, where the reference liquids represent the minimum and maximum allowed viscosities of the tested product ; - put the sample into a clean sample tube; - insert the steel ball into the glass, fill it up completely and close it - return the glass into the test tool and turn it vertically and let all steel balls reach the lower end of the test tubes - after all 3 balls have reached the bottom of the tubes, turn the tool ±180 degrees to a full vertical position ; - the balls will move downwards with a different speed; - the speed of the middle steel ball shall be between the speed of the two other balls or be equal to the speed of one of them; - the check can be made by any equivalent method.
5) Laboratory Viscosity Check - perform the viscosity check in accordance with ASTM D 2196 . - the measurements shall be carried out at rotation speeds of 0.3 rpm ; - the temperatures at which the measurements are made and the spindle number shall be reported; - compare the viscosity values with figures from fluid manufacturer ; the check can be made by any equivalent method .
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De/Anti-Icing of Aircraft on Ground Manual
APPENDICES :
a)
Aircraft Familiarisation Diagrams
b)
Aircraft De-/-anti-icing “NO SPRAY “ areas
c)
Holdover Time Tables
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De/Anti-Icing of Aircraft on Ground Manual
Aircraft de-/-anti-icing familiarisation – DASH 8 400
Aircraft areas for de-/-anti-icing treatment. Wing area Horizontal stabilizer and elevator Vertical stabilizer and rudder
62.10 m² 13.94 m² 14.12 m²
Aircraft de-/-anti-icing familiarisation – CRJ
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De/Anti-Icing of Aircraft on Ground Manual
Aircraft areas for de-/-anti-icing treatment. Wing area Horizontal stabilizer and elevator Vertical stabilizer and rudder
54.54 m² 10.74 m² 13.24 m²
Aircraft de-/-anti-icing familiarisation – F70/F100
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De/Anti-Icing of Aircraft on Ground Manual
Aircraft areas for de-/anti-icing treatment. Wing area Horizontal stabilizer and elevator Vertical stabilizer and rudder
00.00 m² 00.00 m² 00.00 m²
Aircraft de-/-anti-icing familiarisation – A320
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De/Anti-Icing of Aircraft on Ground Manual
Aircraft areas for de-/-anti-icing treatment. Wing area Horizontal stabilizer area Total surface area
122.6 m². 31.0 m².. 153.6 m²
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De/Anti-Icing of Aircraft on Ground Manual Aircraft de-/-anti-icing familiarisation - B737
B737-200/300/400/500 aircrafts areas for de-/-anti-icing treatment. Wing area Horizontal stabilizer area Total surface area
91.10 m² (-200)/105.4 m². 31.41 m². 122.51 m² (-200)/136.81 m².
B737-600/700/800/900 aircrafts areas for de-/-anti-icing treatment. Wing area Horizontal stabilizer area Total surface area
125.00 m². 32.80 m². 157.80 m².
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De/Anti-Icing of Aircraft on Ground Manual Aircraft de-/-anti-icing familiarisation - B767
Aircraft areas for de-/anti-icing treatment. Wing area Horizontal stabilizer area Total surface area
283.30 m². 59.88 m². 343.18 m²
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De/Anti-Icing of Aircraft on Ground Manual Aircraft de-/-anti-icing familiarisation – B 777
Aircraft areas for de-/-anti-icing treatment. Wing area Horizontal stabilizer area Total surface area
427.80 m². 101.26 m². 529.06 m².
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De/Anti-Icing of Aircraft on Ground Manual
b)
Aircraft de-/-anti-icing - 'NO SPRAY' areas
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De/Anti-Icing of Aircraft on Ground Manual AIRBUS A320.
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De/Anti-Icing of Aircraft on Ground Manual BOEING 737
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De/Anti-Icing of Aircraft on Ground Manual BOEING 767
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De/Anti-Icing of Aircraft on Ground Manual BOEING 777
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De/Anti-Icing of Aircraft on Ground Manual
a) TABLE 1 :
OAT
Guidelines for the application of Type I fluid/water mixtures (minimum concentration ) as a function of OAT .
One-Step Procedure De-icing/Anti-icing
-3 °C (27 °F) and above below -3 °C (27 °F) down to LOUT
Holdover Time Tables.
Heated mix of fluid and water with a freeze point of at least 10 °C (18 °F) below OAT
First step: De-icing
Two-Step Procedure Second step: Anti-Icing 1)
Heated water or a heated mix of fluid and water Freeze point of heated fluid mixture shall not be more than 3 °C (5 °F) above OAT
Heated mix of fluid and water with a freeze point of at least 10 °C (18 °F) below OAT
Temperature of water or fluid/water mixtures shall be at least 60 °C (140 °F) at the nozzle. Upper temperature limit shall not exceed fluid and aircraft manufacturer's recommendations. This table is applicable for the use of Type I Holdover Time Guidelines. If holdover times are not required, a temperature of 60 °C (140 °F) at the nozzle is desirable. To use Type I Holdover Time Guidelines, at least 1 liter/m2 (~2 Gals/100ft2) must be applied to the de-iced surfaces. CAUTION: Wing skin temperatures may be lower than OAT. If this condition is identified, a stronger mix (more glycol) may need to be used to ensure a sufficient freeze point buffer. 1) To be applied before first step fluid freezes, typically within 3 minutes.
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De/Anti-Icing of Aircraft on Ground Manual
TABLE 2: -
Guidelines for the application of Type I I , Type I I I , and Type IV fluid/water mixtures (minimum concentrations) as a function of OAT. NOTE : For the application of Type I I I fluids refer to fluid manufacturer's documentation.
Concentration of neat fluid/water mixture in vol%/vol% One-Step Procedure Two-Step Procedure First step: Second step:
OAT 1)
De-icing/Anti-icing
- 3 °C (27 °F) and above below -3 °C (27 °F) to -14 °C (7 °F) below -14 °C (7 °F) to -25 °C (-13 °F) below -25 °C (-13 °F)
De-icing
Anti-Icing2)
Water heated to 60 °C (140 °F) minimum at the nozzle 50/50 or a heated mix of Type I, II, Type II, III, or IV Type II, III, or IV III, or IV with water Heated suitable mix of Type 75/25 I, II, III, or IV with FP not 75/25 heated3) more than 3 °C (5 °F) above Type II, III4), or IV Type II, III,4) or IV actual OAT Heated suitable mix of Type 100/0 I, II, III, or IV with FP not 100/0 heated3) more than 3 °C (5 °F) above Type II, III4), or IV 4) Type II, III , or IV actual OAT Type II/Type III/Type IV fluid may be used below -25 °C (-13 °F) provided that the freezing point of the fluid is at least 7 °C (13°F) below OAT and that aerodynamic acceptance criteria are met (LOUT). Consider the use of Type I/water mix when Type II, III, or IV fluid cannot be used (see table 1). 50/50 heated3)
1) Fluids must only be used at temperatures above their LOUT. 2) To be applied before first step fluid freezes, typically within 3 minutes. 3) Clean aircraft may be anti-iced with unheated fluid. 4)
Type III fluid may be used below -10 °C (14 °F) provided that the freezing point of the fluid is at least 7 °C (13°F) below OAT and that aerodynamic acceptance criteria are met (LOUT).
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De/Anti-Icing of Aircraft on Ground Manual For heated fluid and fluid mixtures, a temperature not less than 60 ° C ( 140 °F) at the nozzle is desirable. When the first step is performed using a fluid/water mix with a freezing point above OAT, the temperature at the nozzle shall be at least 60 °C and at least 1 liter/m 2 (~2 Gals/100ft2) must be applied to the surfaces to be de-iced. Upper temperature limit shall not exceed fluid and Approximate Holdover Times Under Various Weather aircraft manufacturer's recommendations. Type II, III and IV Conditions (hours : minutes) OAT1: Wing skin temperatures CAUTION Fluid may be lower than OAT. If this condition is identified, it shall be verified if a stronger mix (more glycol) may need to be used to ensure a sufficient Active Frost freeze point buffer. As Concentration fluid freezing may occur, 50/50 Type II, III, or IV fluid shall not be used for the anti-icing step of a Neat Fluid/Water °C °F Type I (1) (2) cold soaked wing as ofType the wing the Type surface II III in the area TypeofIV Vol % /indicated Vol % by frost or ice on the lower fuel tank. 100/0 8:00 2:00 12:00 CAUTION 2: An 30 insufficient amount of anti-icing fluid, especially in the second step of a two step procedure, above -1 above 75/25 loss of holdover time. This is particularly 5:00 5:00 may cause a substantial true1:00 when using a Type I fluid 50/50 3:00 0:30 3:00 mixture for the first step (de-icing). 8:00the lowest operational 2:00 12:00 CAUTION 3: Some only be used undiluted. For some fluids use temperature below -1 below 30fluids shall 100/0 75/25refer to fluid manufacturer's documentation. 5:00 1:00 5:00 to -3 tomay 27 differ. For details 50/50 1:30 0:30 3:00 below -3 below 27 100/0 8:00 2:00 10:00 0:45 to -10 to 14 75/25 5:00 1:00 5:00 below -10 below 14 100/00 6:00 2:00 6:00 to -14 to 7 75/25 1:00 1:00 1:00 below -14 below 7 100/0 6:00 2:00 6:00 to -21 to -6 NOTE:
below -21 to -25
below -6 to -13
100/0
2:00
2:00
4:00
Guidelines for holdover times anticipated for Type I, II, III and IV fluid mixtures in active frost conditions as a function of OAT
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De/Anti-Icing of Aircraft on Ground Manual TABLE 3 : (1)
Guideline for Holdover times Anticipated for Type I Fluid Mixtures as a Function of Weather Conditions and OAT In light "Rain and Snow" conditions use "Light Freezing Rain" holdover times One-Step Procedure Two-Step Procedure OAT First step: Second step: De-icing/Anti-icing De-icing Anti-Icing 1)
-3 °C (27 °F) and above below -3 °C (27 °F) down to LOUT
Heated mix of fluid and water with a freeze point of at least 10 °C (18 °F) below OAT
Heated water or a heated mix of fluid and water Freeze point of heated fluid mixture shall not be more than 3 °C (5 °F) above OAT
Heated mix of fluid and water with a freeze point of at least 10 °C (18 °F) below OAT
Temperature of water or fluid/water mixtures shall be at least 60 °C (140 °F) at the nozzle. Upper temperature limit shall not exceed fluid and aircraft manufacturer's recommendations. This table is applicable for the use of Type I Holdover Time Guidelines. If holdover times are not required, a temperature of 60 °C (140 °F) at the nozzle is desirable. To use Type I Holdover Time Guidelines, at least 1 liter/m 2 (~2 Gals/100ft2) must be applied to the de-iced surfaces. CAUTION: Wing skin temperatures may be lower than OAT. If this condition is identified, a stronger mix (more glycol) may need to be used to ensure a sufficient freeze point buffer. 1) To be applied before first step fluid freezes, typically within 3 minutes.
(2)
If positive identification of "Freezing Drizzle" is not possible use "Light Freezing Rain" holdover times (3) Other conditions are: Heavy snow, snow pellets, ice pellets, hail, moderate freezing rain and heavy freezing rain (4) No holdover time guidelines exist for this condition for 0 °C (32°F) and below (5) For holdover times under active frost conditions see the separate frost table (table 3) Type I Fluid / Water Mixture is selected so that the Freezing Point of the mixture is at least 10 °C (18 °F) below actual OAT CAUTION: The time of protection will be shortened in heavy weather conditions. Heavy precipitation rates or high moisture content, high wind velocity or jet blast may reduce holdover time below the lowest time stated in the range. Holdover time may also be reduced when the aircraft skin temperature is lower than OAT. Therefore, the indicated times should be used only in conjunction with a pre-takeoff check. De-icing/anti-icing fluids used during ground de-icing/anti-icing are not intended for - and do not provide protection during flight.
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De/Anti-Icing of Aircraft on Ground Manual TABLE 4 : Guideline for Holdover times Anticipated for Type II Fluid Mixtures as a Function of Weather Conditions and OAT In light "Rain and Snow" conditions use "Light Freezing Rain" holdover times (2) If positive identification of "Freezing Drizzle" is not possible use "Light Freezing Rain" holdover times (3) Other conditions are: Heavy snow, snow pellets, ice pellets, moderate and heavy freezing rain, hail (4) No holdover time guidelines exist for this condition for 0°C (32°F) and below (5) No holdover time guidelines exist for this condition below -10°C (14°F) (6) For holdover times under active frost conditions see the separate frost table (table 3) CAUTION: The time of protection will be shortened in heavy weather conditions. Heavy precipitation rates or high moisture content, high wind velocity or jet blast may reduce holdover time below the lowest time stated in the range. Holdover time may also be reduced when the aircraft skin temperature is lower than OAT. Therefore, the indicated times should be used only in conjunction with a pre-takeoff check. De-icing/anti-icing fluids used during ground de-icing/anti-icing are not intended for - and do not provide protection during flight.
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De/Anti-Icing of Aircraft on Ground Manual TABLE 5 :
Guideline for Holdover times Anticipated for Type I I I Fluid Mixtures as a Function of Weather Conditions and OAT
(1)
In light "Rain and Snow" conditions use "Light Freezing Rain" holdover times If positive identification of "Freezing Drizzle" is not possible use "Light Freezing Rain" holdover times (3) Other conditions are: Heavy snow, snow pellets, ice pellets, moderate and heavy freezing rain, hail (4) No holdover time guidelines exist for this condition for 0°C (32°F) and below (5) For holdover times under active frost conditions see the separate frost table (table 3) (2)
CAUTION: The time of protection will be shortened in heavy weather conditions. Heavy precipitation rates or high moisture content, high wind velocity or jet blast may reduce holdover time below the lowest time stated in the range. Holdover time may also be reduced when the aircraft skin temperature is lower than OAT. Therefore, the indicated times should be used only in conjunction with a pre-takeoff check. De-icing/anti-icing fluids used during ground de-icing/anti-icing are not intended for - and do not provide protection during flight.
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De/Anti-Icing of Aircraft on Ground Manual TABLE 6 :
((1) (2)
(3)
(4) (5) (6)
Guideline for Holdover times Anticipated for Type IV Fluid Mixtures as a Function of Weather Conditions and OAT
In light "Rain and Snow" conditions use "Light Freezing Rain" holdover times If positive identification of "Freezing Drizzle" is not possible use "Light Freezing Rain" holdover times Other conditions are: Heavy snow, snow pellets, ice pellets, moderate and heavy freezing rain, hail No holdover time guidelines exist for this condition for 0 °C (32°F) and below No holdover time guidelines exist for this condition below -10 °C (14°F) For holdover times under active frost conditions see the separate frost table (table 3)
CAUTION: The time of protection will be shortened in heavy weather conditions. Heavy precipitation rates or high moisture content, high wind velocity or jet blast may reduce holdover time below the lowest time stated in the range. Holdover time may also be reduced when the aircraft skin temperature is lower than OAT. Therefore, the indicated times should be used only in conjunction with a pre-takeoff check. De-icing/anti-icing fluids used during ground de-icing/anti-icing are not intended for - and do not provide protection during flight.
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De/Anti-Icing of Aircraft on Ground Manual Abbreviations used in this manual A/C AEA DP FP FWD FZ GND GSE HOT IATA ICAO ICE ISO L/G LH OAT QC QFE QNH RAT RDP REF REG RH RVR RWY SAE STA STD TEMP T/O UTC VIS VMC WX
-
aircraft Association of European Airlines Dewpoint temperature Freezing Point forward freezing ground Ground Support Equipment Holdover time International Air Transport Association International Civil Aviation Organisation icing International Stanardisation Organisation landing gear Left Hand side Outside Air Temperature Quality Control atmospheric pressure at aerodrome elevation see level pressure Ram Air Temperature Remote De-icing Pad reference registration of aircraft Right Hand side Runway Visual Range runway Society of Automotive Engineers station (airport) standard temperature Take Off Coordinated Universal Time visibility Visual Meteorological Conditions weather
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