6 34 fcom sa227 navigation

AIRCRAFT SYSTEMS

NAVIGATION SA227‐ SERIES/FCOM/VTM 6.34.1 PITOT STATIC SYSTEMS

Separate pitot masts are installed, left and right, on the top of the fuselage nose section to provide individual pitot reference to the pilot’s and copilot’s airspeed indicators. Each pitot mast is electrically heated for anti‐icing. Individual pitot heat switches are located on the pilot’s switch panel.

A loadmeter is located on the left console with a left and right selector switch for checking the individual circuits for proper operation. Individual static systems provide reference to the pilot’s and copilot’s rate‐ of‐climb, altimeter, and airspeed indicators. Two static reference buttons for each of these static systems are located on opposite sides of the fuselage aft of the cargo door area.

Air from the unpressurized nose baggage compartment is referenced for the alternate static source through a static reference button. An alternate static selector valve is located on the lower left side of the pilot’s instrument panel. When selection is made to the alternate position, only the pilot’s instruments will be utilizing the alternate static source.

NOTE Refer to Section 4 AFM or (QRH‐SA227‐SERIES Abnormal section) for position error correction data when operating from the alternate static source.

Revision: Original Aug 1,2013

GO/FCOM/SA227‐SERIES/VTM

AIRCRAFT SYSTEMS NAVIGATION

SA227‐ SERIES/FCOM/VTM 6.34.2 Figure 6.34‐1 GROUND PROXIMITY WARNING SYSTEM (GPWS)

The AlliedSignal Aerospace Mk‐VI Ground Proximity Warning System provides visual and aural warnings of possible terrain danger. Visual warnings consists of red and amber annunciator lights on the pilot's and copilot's instrument panels labeled respectively, GPWS P/TEST and BELOW G/S. Failure of the GPWS is annunciated by an amber “GPWS INOP” light centrally located on the instrument panel. A blue/white GPWS FLAP OVRD annunciator/switch provides flap override capability. Figure 6.34‐2 shows the general location of these lights. In some installations, there is only one GPWS P/TEST light and one BELOW G/S light, centrally located with the GPWS FLAP OVRD light and the GPWS INOP light. Aural warnings consist of the following commands: “DON'T SINK”, "BANK ANGLE” (optional), “GLIDESLOPE”, “PULL UP”, “SINK RATE”, TERRAIN–TERRAIN”, “TOO LOW, TERRAIN”, “TOO LOW, GEAR”, "TOO LOW, FLAPS", “FIVE HUNDRED” (optional), “TWO HUNDRED” (optional) and “MINIMUMS– MINIMUMS”.

GPWS INSTRUMENT PANEL LIGHTS

GPWS FLAP OVRD BLUE/WHITE

Figure 6.34‐2

The GPWS is operable when electrical power is ON and power is provided to the avionics system through the Avionics Master Switch. Circuit protection is provided by the following circuit breakers recessed into the pilot's side panel.

 GPWS CMPTR (1 amp) GPWS ADC (1 amp) RAD ALT (1 or 2 amps)

The GPWS continually monitors the following items:

1.

GPWS computer power supplies and other circuits.

2.

Radio altimeter flag, signal and interface wiring.

3.

Air data flag, signals and interfacing wiring.

4.

GPWS interface wiring to landing gear and flaps.

Failure of any of these items will be indicated by illumination of the GPWS INOP annunciator.

The following equipment must be functional and operating to provide inputs and outputs for the Ground Proximity Warning System:

1.

Air data source 2.

Radio Altimeter 3.

Pilot's glideslope receiver 4.

Aircraft audio system

Revision: Original Aug 1,2013

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AIRCRAFT SYSTEMS

NAVIGATION SA227‐ SERIES/FCOM/VTM 6.34.3 GROUND PROXIMITY WARNING SYSTEM (GPWS) (continued)

The GPWS provides warnings for the following conditions:

Mode 1 Excessive rate of descent with respect to terrain when below 2450 feet (747 m) above ground level (AGL).

Annunciation: “SINK RATE” and “PULL UP”

Mode 2 Excessive rate of closure to terrain when below 1800 feet (549 m) AGL.

Annunciation: “TERRAIN – TERRAIN” and “PULL UP”

Mode 3 Altitude loss after takeoff or missed approach before attaining 925 feet (282 m) AGL.

Annunciation: “DON'T SINK”

Mode 4 Approach to within 500 feet (152 m) AGL with landing gear UP or to within 170 feet (52 m) AGL with landing gear DOWN and flaps not selected to DOWN position, or proximity to terrain on takeoff or go‐around.

Annunciation: “TOO LOW, TERRAIN”, “TOO LOW, GEAR” or “TOO LOW, FLAPS”.

Mode 5 Flying excessively low on an ILS glideslope when below 925 feet (282 m) AGL with gear down.

Annunciation: “GLIDESLOPE”

• The glideslope warning function provides visual and aural indications when flying more than 1.3 dots below the glideslope beam.

• The following conditions must be present for this mode to work:

1. NAV 1 tuned to the ILS frequency for the approach being flown.

NOTE

The GPWS uses glideslope information from the pilot's HSI or EHSI only.

However, the ILS frequency in the pilot's EHSI may be tuned from either on‐side or cross‐side radios.

2. Altitude less than 925 feet (282 m) AGL. 3. Landing gear down.

4. The glideslope cancel function has not been activated.

• The glideslope mode can be de‐activated by momentarily depressing the BELOW G/S switch/ annunciator. This feature is only operable when the airplane is below 925 feet (282 m) AGL.

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AIRCRAFT SYSTEMS NAVIGATION SA227‐ SERIES/FCOM/VTM GROUND PROXIMITY WARNING SYSTEM (GPWS) (continued)

6.34.4

•

If the glideslope mode has been cancelled, it will automatically reset to normal operation by ascending above 1900 feet (579 m) AGL or by landing. It may be reset manually by briefly selecting a VOR frequency with the appropriate NAV receiver.

NOTE

Glideslope indications may be present when flying a back course approach. These glideslope signals are unreliable and may cause nuisance below g/s warnings. These warnings can be avoided by using the glideslope cancel feature.

Mode 6

Descent below (1) the selected minimum descent altitude (MDA) or decision height (DH), (2) 500 feet (152 m), (3) 200 feet (61 m) AGL, and (4) excessive bank angle.

Annunciation: “MINIMUMS – MINIMUMS, "FIVE HUNDRED”, “TWO HUNDRED”, and “BANK ANGLE” (bank angle not installed on Aeronaves TSM aircraft)

•

An aural advisory sounds when the airplane descends below the DH altitude selected on the radio altimeter indicator and at 500 and 200 feet AGL (152 and 61 m) and also when steep bank angles are encountered.

The following illustrations and explanations describe the operation and limitations of each warning mode.

MODE 1 – Excessive Descent Rate

When the outer alert envelope is penetrated, the "DON'T SINK" voice message is annunciated every three seconds and the GPWS P/TEST lamp illuminates. Selecting GPWS FLAP OVRD increases the allowable altitude loss. Additional desensitizing of the envelope occurs above 700 feet (213 m) at the rate of 5 feet additional altitude loss allowed per second.

MODE 2A – Excessive Terrain Closure Rate

When the outer alert envelope is penetrated, the "TERRAIN–TERRAIN" voice message occurs once and the GPWS P/TEST lamp illuminates. If the envelope penetration persists, then the "PULL UP" voice message will occur repetitively. "PULL UP" warnings will cease when the envelope is exited but GPWS P/TEST lamp will remain illuminated until a barometric altitude gain of 300 feet. The envelope will expand as air speed increases above 220 KIAS.

Revision: Original Aug 1,2013

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AIRCRAFT SYSTEMS NAVIGATION SA227‐ SERIES/FCOM/VTM GROUND PROXIMITY WARNING SYSTEM (GPWS) (continued)

6.34.5

MODE 2B – Excessive Terrain Closure Rate (Flaps Down) When the outer alert envelope is penetrated, the "TERRAIN–TERRAIN" voice message annunciates and the GPWS P/TEST lamp illuminates. If the landing gear is down and either flaps are down or GPWS FLAP OVRD is selected then the "TERRAIN" message will be repetitive. Otherwise a repetitive "PULL UP" message will occur. The voice message will cease and the GPWS P/TEST lamp will extinguish when the envelope is exited.

MODE 3 – Descent After Takeoff

When the outer alert envelope is penetrated, the "DON'T SINK" voice message is annunciated every three seconds and the GPWS P/TEST lamp illuminates. Selecting GPWS FLAP OVRD increases the allowable altitude loss. Additional desensitizing of the envelope occurs above 700 feet (213 m) at the rate of 5 feet additional altitude loss allowed per second.

MODE 4A – Proximity to Terrain (Gear Up)

With airplane speed less than 178 KIAS, penetration of the alert envelope will result in a repetitive "TOO LOW, GEAR" voice message and illumination of the GPWS P/TEST lamp. Above 178 KIAS, penetration will result in a repetitive "TOO LOW, TERRAIN" message.

MODE 4B – Proximity to Terrain (Gear Down/ Flaps Up) With airplane speed less than 150 KIAS, penetration of the alert envelope will result in a repetitive "TOO LOW, FLAPS" annunciation when descending below 170 feet (52 m) AGL.GPWS P/TEST lamp will also illuminate. With airplane speed above 150 KIAS the "TOO LOW, TERRAIN" voice message annunciates when descending below a speed‐expanded ceiling of 170 – 750 feet (52 – 229 m).

Revision: Original Aug 1,2013

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AIRCRAFT SYSTEMS NAVIGATION SA227‐ SERIES/FCOM/VTM GROUND PROXIMITY WARNING SYSTEM (GPWS) (continued)

6.34.6

MODE 4C – Proximity to Terrain (Takeoff)

When the airplane descends below an altitude that is 3/4 of its peak radio altitude on takeoff, the "TOO LOW, TERRAIN" voice message will annunciate every three seconds and the GPWS P/TEST lamp will illuminate.

MODE 5 – Descent Below Glideslope

When the airplane is below 925 feet (282 m) on ILS approach, the "GLIDESLOPE" voice message will annunciate at a variable rate according to radio altitude and glideslope deviation. Initial "GLIDESLOPE" warnings are 6 dB below normal audio levels (soft). Penetration of the inner warning envelope will cause "GLIDESLOPE" warnings at normal audio levels (louder).

MODE 6 – Altitude Callouts/Excessive Bank Angle

When the airplane descends below the selected decision height on the radio altimeter indicator, the "MINIMUMS–MINIMUMS" voice message will annunciate. Optional altitude callouts at "FIVE HUNDRED" and "TWO HUNDRED" feet will also be annunciated. The optional "BANK ANGLE" voice message will occur when the airplane exceeds a 50o bank angle at or above 190 feet (58 m).

Sensitivity of this function increases with reduced height above the ground, with the warning occurring at 15o bank at ground level.

NOTE Aeronaves TSM Bank Angle Callouts are not installed.

Revision: Original Aug 1,2013

GO/FCOM/SA227‐SERIES/VTM

AIRCRAFT SYSTEMS

NAVIGATION SA227‐ SERIES/FCOM/VTM 6.34.7 GROUND PROXIMITY WARNING SYSTEM (GPWS) (continued)

ALERT/CAUTION/WARNING VOICE PRIORITY

Only ONE voice message is produced at a time.

The highest priority message takes precedence, and IMMEDIATELY interrupts any lower priority message. If the aircraft is in a situation that meets more than one warning or alert envelope, the higher priority message will be heard until that envelope is exited. If the aircraft is still within a different alert envelope at that time, the voice message will switch to the appropriate call.

The following table shows the voice output messages that are activated for each alert, caution, and warning mode. The messages are arranged in order of priority, from the highest priority at the top of the table, to the lowest priority at the bottom of the table.

ALERT/WARNING CONDITION VOICE MESSAGE GPWC INVALID (Stop ALL Voice Messages) EXTERNAL AUDIO SUPPRESSION* NO MESSAGES ALLOWED MODE 1 Urgent PULL UP! PULL UP! Immediate Repeat MODE 2 PULL‐UP PULL UP Immediate Repeat MODE 2 TERRAIN‐TERRAIN TERRAIN‐TERRAIN (Once per Mode 2 envelope penetration) MODE 2 TERRAIN TERRAIN (pause) 3 Second Repeat MODE 4 TOO LOW, TERRAIN TOO LOW, TERRAIN (pause) 3 Second Repeat MODE 6 DECISION HEIGHT MINIMUMS‐MINIMUMS (pause) 3 Seconds total time. One message per approach.

MODE 6 ALTITUDE CALLOUT FIVE HUNDRED (pause) 3 Seconds total time. One message per approach.

MODE 6 ALTITUDE CALLOUT TWO HUNDRED (pause) 3 Seconds total time. One message per approach.

MODE 4 TOO LOW, GEAR TOO LOW, GEAR (pause) 3 Second Repeat MODE 4 TOO LOW, FLAPS TOO LOW, FLAPS (pause) 3 Second Repeat MODE 1 SINK RATE and MODE 5 GLIDESLOPE, SINK RATE (pause) 3 Second Repeat GLIDESLOPE MODE 1 SINK RATE SINK RATE (pause) 3 Second Repeat MODE 3 DON'T SINK DON'T SINK (pause) 3 Second Repeat MODE 5 GLIDESLOPE GLIDESLOPE PAUSE GLIDESLOPE (Variable pause) TIME MODE 6 ALTITUDE CALLOUTS BANK ANGLE (pause) 3 Second Repeat No Alert/Warning No Message * Activated by the SAS. Table 6.34‐1

NOTE Aeronaves TSM Bank Angle Callouts are not installed.

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AIRCRAFT SYSTEMS NAVIGATION

Revision: Original Aug 1,2013

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6.34.8