16 i 2 to ac system three inv

FAAAPPROVED AIRPLANE

FLIGHT

MANUAL

SUPPLEMENT

FOR METRO ICAO ANNEX AC SYSTEM

III, SA227-AC 8 - 16,000

WITH

THREE

POUNDS INVERTERS

Registration No. Serial No. This supplement must be attached to the FAA Approved Airplane Flight Manual when the aircraft has been modified in accordance with Fairchild Aircraft Corporation Drawing No. 27-13960 to incorporate a third inverter. The information contained in this document supplements or supersedes the basic manual only in those areas listed. For limitations and procedures information not contained in this supplement, consult the basic Airplane Flight Manual.

FAA Approved by: Kg? L. B. Andriesen, Manager Rotorcraft Directorate Aircraft Certification Service Department of Transportation Federal Aviation Administration Southwest Region Ft. Worth, Texas 76193-0100 Date:

THIRD INVERTER FAA Approved: MAY 22189

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METRO III – ICAO ANNEX 8 TABLE OF CONTENTS ITEM

PAGE

List of Revisions ....................................................................................................................................... 3 Section 1 – Limitations (No Change) ................................................................................................... 5 Section 2 – Normal Procedures........................................................................................................... 5 Section 3 – Emergency Procedures (No Change) .............................................................................. 5 Section 3A – Abnormal Procedures ...................................................................................................... 6 Section 4 – Performance (No Change) .............................................................................................. 7 Section 5 – Weight and Balance (No Change) .................................................................................... 7 Section 6 – Manufacturer's Data ......................................................................................................... 8

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THIRD INVERTER FAA Approved: MAY 22/89

METRO III - ICAO ANNEX 8 LIST

OF REVISIONS

Revisions to the Airplane Flight Manual provide current information applicable to operation of the METRO III aircraft. Revised pages should be inserted in the manual to replace existing pages or to add additional pages, as applicable. The manual is valid only when all current revisions are incorporated.

Revision Number N/A

Revised Pages All

FAA Approved Description of Revision Supplement reprinted to Reissue A. Supplement

Signature

Date

renumbered and complement AFM Replaces former 2.

A black bar in the margin of a revised page shows the current change.

THIRD INVERTER FAA Approved: MAY 22189

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METRO III – ICAO ANNEX 8

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THIRD INVERTER FAA Approved: MAY 22/89

METRO III – ICAO ANNEX 8 SECTION 1 . . . . . . .LIMITATIONS No change.

SECTION 2 . . . . . . .NORMAL PROCEDURES INTRODUCTION Installation of the third inverter in the Metro III requires that the inverter switch position nomenclature be changed. Normal operation of the inverters is with inverters Number 1 and Number 2 operating.

Installation of the third inverter changes normal operating procedures only at line item 5 of the battery start procedure and at line item 8 of the GPU start procedure, as shown below. Refer to Section 2 of the basic AFM for normal procedures and information not contained in this supplement.

BATTERY START 1. through 4 .............................................................................................................SEE BASIC AFM *5. Inverters (Check No. 3, then No. 1 & 2) .................................................................................... ON 6. through 24 ........................................................................................................... SEE BASIC AFM

GROUND POWER UNIT (GPU) START 1. through 7 .............................................................................................................SEE BASIC AFM *8. Inverters (Check No. 3, then No. 1 & 2) .................................................................................... ON 9. through 26 ........................................................................................................... SEE BASIC AFM

SECTION 3 . . . . . . .EMERGENCY PROCEDURES No change.

THIRD INVERTER FAA Approved: MAY 22/89

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METRO III – ICAO ANNEX 8 SECTION 3A. . . . . . .ABNORMAL PROCEDURES INTRODUCTION When the METRO III is equipped with three inverters, the No. 1 inverter powers the left AC buses and the No. 2 inverter powers the right AC buses during normal operations. No. 3 inverter is in standby status to automatically power either the left or right AC buses if the respective No. 1 or No. 2 inverter fails. No. 3 inverter will power both left and right AC buses automatically if both No. 1 and No. 2 inverters should fail. It will also power both sides if it is selected by moving the inverter selector switch to No. 3. This section of Supplement 2 addresses abnormal indications and operations of only the three-inverter system. Refer to Section 3A of the basic AFM for remaining abnorma procedures.

ANNUNCIATOR PANEL

LIGHT ILLUMINATED

INDICATES THAT

L AC BUS

With No. 1 and No. 2 inverters selected: No. 1 inverter and automatic transfer system have failed. Bus is not powered. See page 7.

R AC BUS

With No. 1 and No. 2 inverters selected: No. 2 inverter and automatic transfer system have failed. Bus is not powered. See page 7.

L AC BUS and R AC BUS

a. With No. 1 and No. 2 inverters selected: No. 1 inverter, No. 2 inverter, and automatic transfer system have failed or all inverters have failed. Neither bus is powered. See page 7. b. With No. 3 inverter selected, it has failed. Neither bus is powered. See page 7.

NO. 3 INV

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System is operating in abnormal mode. No. 3 inverter is powering left, right, or all AC buses.

THIRD INVERTER FAA Approved: MAY 22/89

METRO III – ICAO ANNEX 8 SECTION 3A. . . . . . .ABNORMAL PROCEDURES (continued) AC BUS FAILURE LIGHT ILLUMINATED *1. Inverter Selector Switch ............................................................... REPOSITION FROM No. 1 & 2 TO NO. 3 OR FROM NO. 3 TO NO. 1 & 2, AS REQUIRED. NOTE It is normal for the L or R AC BUS failure lights to be illuminated momentarily during the two second delay between No. 1 and No. 2 inverter failure and automatic transfer to No. 3 inverter.

MANUAL GROUND START PROCEDURES Line item 5 of the battery manual start procedure and line item 8 of the GPU manual start procedure are changed to shown below.

BATTERY MANUAL START 1. through 4 .............................................................................................................SEE BASIC AFM *5. Inverters (Check No. 3, then No. 1 & 2) .................................................................................... ON 6. through 24 ........................................................................................................... SEE BASIC AFM

GROUND POWER UNIT (GPU) MANUAL START 1. through 7 .............................................................................................................SEE BASIC AFM *8. Inverters (Check No. 3, then No. 1 & 2) .................................................................................... ON 9. through 26 ........................................................................................................... SEE BASIC AFM

SECTION 4. . . . . . .PERFORMANCE No change.

SECTION 5. . . . . . .WEIGHT AND BALANCE No change.

THIRD INVERTER FAA Approved: MAY 22/89

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METRO III – ICAO ANNEX 8 SECTION 6. . . . . . .MANUFACTURER'S DATA INTRODUCTION The appropriate electrical systems descriptions provided in Section 6 of the basic AFM are replaced by the following when the third inverter is installed.

ELECTRICAL SYSTEMS Left and right 115 VAC and 26 VAC buses provide power for AC equipment. The left and right buses are not tied together. The AC buses are powered by the No. 1 and No. 2 inverters normally, or by the No. 3 inverter when required and as shown in Figure 1.

AC POWER DISTRIBUTION Three DC-powered static inverters are installed. The pilot can select primary inverters No. 1 and No. 2 (normal operation) or inverter No. 3 (abnormal or preflight operation). In case of a failure of inverter No. 1 or No. 2 with the selector switch in the No. 1 & 2 position, the No. 3 inverter will come on automatically and pick up the bus from the failed inverter. If both No. 1 and No. 2 inverters should fail, the No. 3 inverter will provide power to all AC buses. Each of the three inverters provides both 115 VAC and 26 VAC buses. Figure 1 shows the sources of bus power when operating under normal and abnormal conditions. Figure 2 is an AC system schematic.

Operation The inverters are controlled by a switch installed on the copilot's switch panel. The No. 1 inverter is powered from the left essential bus, the No. 2 from the right essential bus, and No. 3 is powered from the bus opposite to that of the failed inverter in the automatic transfer mode and from both buses when the No. 3 inverter is selected by the cockpit switch. The No. 1 inverter powers the left AC buses, and the No. 2 inverter powers the right AC buses. If either inverter fails with the selector switch in the No. 1 & 2 position, the corresponding bus fail light will come on for approximately two seconds and then go out when the No. 3 inverter comes on. The No. 3 INV annunciator light will be illuminated to alert the crew that the third inverter is being used.

With the selector switch in the No. 3 position, the No. 3 inverter powers all AC buses and the No. 3 INV annunciator light will be illuminated. A failure of the No. 3 inverter in that switch position will cause both AC bus fail lights to illuminate and the No. 3 INV light to extinguish. The system will not transfer back to inverters No. 1 and No. 2 in this case.

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THIRD INVERTER FAA Approved: MAY 22/89

METRO III – ICAO ANNEX 8 SECTION 6. . . . . . .MANUFACTURER'S DATA (continued) AC VOLTMETER, NO. 3 INVERTER STATUS LIGHT, AND AC BUS FAILURE LIGHTS A bus selectable voltmeter, a No. 3 inverter status light, and two bus failure caution lights comprise the AC warning and monitoring systems. The AC voltmeter is powered from the 115 volt bus system. A selector switch allows either bus to be monitored. Each 115 volt bus also powers a bus failure relay.

When voltage is present at the bus, the relay is energized and breaks the path for power to the AC bus caution light. If power is lost to the bus, the relay relaxes and the light illuminates, indicating a loss of bus power.

The No. 3 INV caution light illuminates to indicate that the AC system is operating in an abnormal mode. This light is energized only when No. 3 inverter is on, whether selected by the cockpit switch or by the automatic switching unit following failure of one, or both, of the primary inverters. Illumination of the No. 3 INV caution light should be verified when No. 3 inverter is checked prior to engine starts.

THIRD INVERTER FAA Approved: MAY 22/89

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METRO III – ICAO ANNEX 8 AC BUS POWER SOURCES

INVERTER SELECTOR SWITCH POSITION

INVERTER STATUS

LEFT AC BUSES POWERED BY:

RIGHT AC BUSES POWERED BY:

NO. 1 ON NO. 2 ON NO. 3 OFF

NO. 1 INV.

NO. 2 INV.

NO. 1 FAILED NO. 2 ON NO. 3 ON

NO. 3 INV.

NO. 2 INV.

NO. 1 ON NO. 2 FAILED NO. 3 ON

NO. 1 INV.

NO. 3 INV.

NO. 1 FAILED NO. 2 FAILED NO. 3 ON

NO. 3 INV.

NO. 3 INV.

UNPOWERED

UNPOWERED

NO. 1 & 2

OFF

ALL INV. OFF

NO. 3

NO. 1 OFF NO. 2 OFF NO. 3 ON

NO. 3 INV.

NO. 3 INV.

NO. 3

NO. 1 OFF NO. 2 OFF NO. 3 FAILED

UNPOWERED

UNPOWERED

FIGURE 1 Supplement A-2 Page 10 of 12 8AC

THIRD INVERTER FAA Approved: MAY 22/89

METRO III – ICAO ANNEX 8 SIMPLIFIED AC DISTRIBUTION SCHEMATIC LEFT 26 VAC BUS

RIGHT 26 VAC BUS

LEFT 115 VAC BUS

RIGHT 115 VAC BUS

LEFT INVERTER SELECTION AND AUTOMATIC SWITCHING UNIT

RIGHT INVERTER SELECTION AND AUTOMATIC SWITCHING UNIT

26 115 VAC VAC OUTPUT OUTPUT

26 115 VAC VAC OUTPUT OUTPUT

115 26 VAC VAC OUTPUT OUTPUT

NO. 1 INVERTER

NO. 3 INVERTER

NO. 2 INVERTER

FIGURE 2 THIRD INVERTER FAA Approved: MAY 22/89

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THIRD INVERTER FAA Approved: MAY 22/89