757
MAINTENANCE MANUAL
(f) The fire bell sounds, on the flight deck aural warning
speakers.
(4) A dual-loop inoperative indication is given by the following:
(a) The amber FAIL P-RESET switchlight, on the P8 control stand,
comes on.
(5) A single-loop inoperative or alarm signal indication is given by the
following:
(a) The appropriate status/maintenance message is displayed on
EICAS (P2):
1) L TURB OH DET 1 or 2.
2) R TURB OH DET 1 or 2.
(6) Test circuit failures may not provide an inoperative signal at the
moment of failure. These inoperative loops can only be detected
during a system test.
B. Test____
(1) When a test occurs, the AFOLTS cards send out signals to each loop
of the detection systems. Returned signals indicate operating
loops. If any loop is found inoperative, AFOLTS reconfigures that
system to operate on the remaining loop. If the remaining loop
sustains an alarm or inoperative condition, then a fire warning or
fail indication results.
(2) Power-up mode:
(a) Whenever power is first applied, an automatic system self-test
occurs. All single-loop status/maintenance messages are
momentarily displayed on EICAS (P2). If any loop is found
inoperative , then the appropriate loop message remains on
EICAS display, and the system is reconfigured to the other
loop. If both loops of a system are found inoperative, then
the FAIL P-RESET switchlight (on P8) comes on, and EICAS
displays the advisory message - FIRE/OVHT SYS. Cockpit fire
warnings will not be initiated by a power-up test.
(3) Manual system test:
(a) When the ENG switch on the fire/overheat test panel (on P8) is
pressed and held, the engine turbine cooling overheat and strut
overheat detection systems go through a self-test. All loop
messages are displayed on EICAS, and after a two-second delay,
a successful test terminates with all fire and overheat
indications. The indications for the turbine overheat test
are:
1) The red L and R fire switch handles light up, and unlock
(on P8).
2) The red L and R fuel control switches light up (on P10).
3) The red FIRE light comes on (on P1-3).
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757 MAINTENANCE MANUAL
4) EICAS displays L and R ENGINE FIRE (warnings).
5) EICAS displays L TURB OH DET 1 and 2 (maintenance)
6) EICAS displays R TURB OH DET 1 and 2 (maintenance)
7) The red master warning lights.
8) The fire bell sounds on the aural warning speakers.
(b) When the ENG switch is released, all messages and indications should clear - except for any inoperative loop messages which will remain on EICAS. The FAIL P-RESET switchlight, and EICAS advisory message - FIRE/OVHT SYS, will also remain on if there is a dual-loop inoperative.
(4) The manual system test will not invalidate an alarm in progress.
C. Control
_______
(1) Turn-on procedure:
(a)
Provide electrical power (Ref 24-22-00).
(b)
Check that the following overhead panel P11 circuit breakers are closed: 1) 11B20, FIRE DETECTION L ENGINE 1 2) 11B21, FIRE DETECTION L ENGINE 2 3) 11B22, FIRE DETECTION R ENGINE 1 4) 11B23, FIRE DETECTION R ENGINE 2 5) 11J26, FIRE DET ALTN PWR ENGINE LEFT 6) 11J27, FIRE DET ALTN PWR ENGINE RIGHT
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FAULT ISOLATION/MAINT MANUAL
ENGINE TURBINE COOLING OVERHEAT DETECTION SYSTEM
* SEE THE WDM EQUIPMENT LIST 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：757 AMM 飞机维护手册 防火 FIRE PROTECTION 1(45)
