APU Overtemperature Thermocouple - Installation 501
49-52-71 Figure 401 Aug 01/74
Page 402
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
D. Coat threads of retainer bolt with antiseize compound; install bolt with washer. Tighten bolt to torque range of 50 to 70 pound-inches.
E. Secure cable assembly to tubing assembly with clamps. Ensure that thermocouple leads do not chafe adjacent lines, components or structure.
F. Connect electrical connector to overtemperature control switch.
5. 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 and stow rods. Close and latch access door.
C. Position BATTERY SWITCH to ON and remove placard.
500
Aug 15/73 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 49-52-71 Page 403
OVERTEMPERATURE CONTROL SWITCH - REMOVAL/INSTALLATION
1. Prepare for Overtemperature Control Switch Removal
A. Position BATTERY SWITCH and APU START SWITCH to OFF and placard.
B. Open circuit breaker on M280 module, APU accessory unit on E3-3 electronic shelf.
C. Open APU compartment access door latches and open 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.
2. Remove Overtemperature Control Switch (Fig. 401)
A. Disconnect electrical connectors.
B. Remove screws securing switch to cooling air crossover duct.
NOTE: Do not remove cap from switch.
3. Install Overtemperature Control Switch (Fig. 401)
CAUTION: PRIOR TO INSTALLING NEW SWITCH, CHECK PLUG D1572 TERMINALS A AND B TO GROUND FOR POSSIBLE SHORTING. A SHORT IN THE WIRE HARNESS WILL DAMAGE NEW SWITCH.
A. Install switch, securing with screws and washers.
B. Connect electrical connectors and secure as required.
4. Restore Airplane to Normal
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 and stow 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 placards.
503
May 15/77 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 49-52-81 Page 401
Overtemperature Control Switch Installation 500
49-52-81 Figure 401 Aug 15/73
Page 402
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
OVERTEMPERATURE CONTROL SWITCH - ADJUSTMENT/TEST
1. General
A. The following procedures provide information for checking the overall integrity of the overtemperature switch system; adjusting the set point of the overtemperature switch, and instruction for deactivating the overtemperature switch if failed and no replacement is available.
2. Test Overtemperature Control Switch System (Fig. 501)
A. Gain access to overtemperature control switch in APU compartment.
B. Disconnect J1.
C. Operate APU (AMM 49-11-0/201).
D. Observe duct pressure indicator.
(1)
Position engines 1 and 2 BLEED switches (located on overhead panel P5) to OFF.
(2)
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