4. Restore Airplane to Normal Configuration
A. Position lower shroud against upper shroud and close shroud latches.
CAUTION: MAINTAIN A MINIMUM CLEARANCE OF 0.18 INCH BETWEEN ENGINE PLUMBING, FIRE DETECTOR, CLAMPS AND INSIDE SURFACE OF LOWER SHROUD.
EXERCISE EXTREME CARE NOT TO DAMAGE SHROUD DRAIN LINES WHEN HANDLING SHROUD.
B. Disengage APU compartment access door support rods. Close and latch access door.
C. Close the circuit breaker on M280 module-APU accessory unit on E3-3 electronic shelf.
D. Position BATTERY SWITCH to ON and remove placard.
F17947
Fuel Solenoid Valve Installation 504
49-31-31Page 402 Figure 401 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. Aug 01/95
FUEL SOLENOID VALVE - ADJUSTMENT/TEST
1. Fuel Solenoid Valve Test
A. General
(1) The fuel solenoid valve test gives a fast indication that there is a problem with the fuel solenoid valve. The fuel solenoid valve is attached to the housing of the fuel control unit.
B. Test the Fuel Solenoid Valve
(1)
Start and operate the APU (AMM 49-11-0/201).
(2)
Let the APU operation become stable with no load applied.
(3)
Open the circuit breaker on the M280 module - APU control unit on the E3-3 electronic shelf.
(4)
If the APU will not shut down with the circuit breaker open, do the following:
(a)
Shut down the APU (AMM 49-11-00/201) and tag the APU master switch DO-NOT-OPERATE.
(b)
Replace the fuel solenoid valve (AMM 49-31-31/401).
(c)
Do the fuel solenoid valve test again.
(5)
If the APU does shut down with the circuit breaker open, do the following:
(a)
Position the APU master switch. 1) APU’s WITHOUT 60-SECOND SHUTDOWN DELAY; Position APU master switch to OFF.
2) APU’s WITH 60-SECOND SHUTDOWN DELAY; Position APU master switch to OFF DELAYED.
(b)
Position battery switch to OFF.
(c)
Close the circuit breaker on the M280 module - APU control unit on the E3-3 electronic shelf.
501
Aug 01/96 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 49-31-31 Page 501
COMBUSTOR UNIT - REMOVAL/INSTALLATION
1. General
A. The fuel atomizer, combustor cap and combustion chamber liner assemblies are removed, cleaned, examined and reinstalled as a unit.
2. Prepare for Combustor Unit Removal
A. Position BATTERY SWITCH and APU START SWITCH to OFF and placard that APU maintenance is "in work."
B. Open the circuit breaker on M280 module-APU accessory unit on E3-3 electronic shelf.
C. Open APU compartment access door latches and open access door. Install door support rods.
D. Support lower shroud, open shroud latches, and remove shroud.
CAUTION: EXERCISE EXTREME CARE NOT TO DAMAGE SHROUD DRAIN LINES WHEN HANDLING SHROUD.
3. Remove Combustor Unit (Fig. 401)
A. Disconnect high voltage lead from igniter plug.
WARNING: CURRENT INVOLVED IN IGNITION SYSTEM IS OF VERY HIGH VOLTAGE AND CAN BE FATAL. BE SURE THAT POWER IS REMOVED FROM IGNITION SYSTEM FOR A MINIMUM OF 3 MINUTES BEFORE ANY DISCONNECTIONS ARE MADE. AFTER DISCONNECTING HIGH VOLTAGE LEAD, ENSURE COMPLETE DISCHARGE OF CAPACITORS IN IGNITION UNIT BY IMMEDIATELY SHORTING HIGH VOLTAGE LEAD TERMINAL TO GROUND.
B. Disconnect high-pressure fuel line from fitting on fuel atomizer and loosen fitting on fuel solenoid valve. Release line to rotate. Catch dripping fuel in suitable container.
C. Rotate high pressure fuel line away from combustor cap to clear cap.
D. Disconnect fuel drain line from combustion chamber cap.
NOTE: If engine identification plate is reusable, remove attaching screws and identification plate. Retain identification plate for installation on replacement combustor unit. If identification plate is damaged, carefully note all information for transfer to new identification plate. The identification plate on latest series engines has been relocated to a bracket located on the turbine plenum assembly.
E. Remove clamp attaching combustor unit to turbine plenum.
(1)
If required, use a rubber mallet and tap lightly to loosen the clamp.
(2)
Discard the nut.
(3)
Examine the T-bolt on the clamp for wear, galling, stripping, or crossed threads.
(a) If signs of damage are found, replace the clamp.
F. Remove combustor unit and discard packing.
NOTE: Examine hot section components for damage per 49-11-0, Inspection/Check, par. 3.A.(2) and 3.A.(3).
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