S 864-032
 S 754-033
 S 754-034
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A

757 MAINTENANCE MANUAL
 S 754-040
 (31)
 Make sure the EICAS messages L ENG FIRE LP 1 and 2 show on the bottom display.

 S 864-035

 (32)
 Open these circuit breakers on the P11 panel and attach DO-NOT-CLOSE tags:

 (a)  
11B20, FIRE DETECTION L ENGINE 1

 (b)  
11B21, FIRE DETECTION L ENGINE 2

 S 434-036
 (33) Install the printed circuit cards, M681 and M682.
 D. Put the airplane back to its usual condition.
 S 864-037
 (1)  Remove DO-NOT-CLOSE tags and close these circuit breakers on the P11 panel:
 NOTE: Close the system 1 and 2 circuit breakers at the same time.
____
 (a)  
11B20, FIRE DETECTION L ENGINE 1

 (b)  
11B21, FIRE DETECTION L ENGINE 2

 (c)  
11B22, FIRE DETECTION R ENGINE 1

 (d)  
11B23, FIRE DETECTION R ENGINE 2

 (e)  
11B24, FIRE DETECTION APU 1

 (f)  
11B25, FIRE DETECTION APU 2

 (g)  
11B26, FIRE DETECTION CARGO 1

 (h)  
11B27, FIRE DETECTION CARGO 2

 (i)  
11J24, FIRE DET ALTN PWR CARGO

 (j)  
11J25, FIRE DET ALTN PWR APU

 (k)  
11J26, FIRE DET ALTN PWR ENGINE LEFT

 (l)  
11J27, FIRE DET ALTN PWR ENGINE RIGHT

 S 864-038
 (2)  Remove the DO-NOT-CLOSE tags and close these circuit breakers on the P6 panel:
 (a)  
6C1, FUEL COND CONT L

 (b)  
6C2, FUEL COND CONT R

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757 MAINTENANCE MANUAL
 S 864-039
 (3) Remove electrical power if it is not necessary (Ref 24-22-00).
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1.

2.

3.

757 MAINTENANCE MANUAL
 STRUT OVERHEAT DETECTION - DESCRIPTION AND OPERATION
____________________________________________________
General
_______
 A.  Dual-loop overheat detection systems are installed in each engine area. These systems monitor strut temperatures, and provide alerts for overheat conditions.
 B.  Both systems (left and right strut overheat detection) use power from the 28-volt DC battery bus, with alternate power from the right main DC bus. The circuit breakers for each system are on overhead circuit breaker panel P11. The system contains no on/off switches.
 C.  The overheat detection systems are each composed of a dual-loop detector. Thus, each loop of an overheat detection system has three detector switches. These switches are electrically connected in parallel, so that one switch can trigger an alarm signal for that loop.
 D.  Each engine has a fire/overheat logic/test card, and both systems have one fire/overheat test panel.
 E.  Both systems operate in AND logic. Thus, both loops of a system must
 sense an overheat condition in order for an alarm to be given.Component Details (Fig. 1)
_________________
 A.  Strut Overheat Detectors________________________
 (1)  
An overheat detector is a bi-metallic switch. When temperature exceeds the detectors trip temperature, the switch closes a path to ground. Each detector switch is identical except for trip temperature.

 (2)  
　
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