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757 MAINTENANCE MANUAL
 E. Put the Airplane Back to Its Usual Condition
 S 445-013
 (1)  
Put the safety-sensitive systems back to their initial conditions (Ref 32-09-02/201).

 S 445-012

 (2)  
Do the activation procedure for the spoilers if you did the deactivation procedure (Ref 27-61-00/201).

 S 865-017

 (3)  
Remove electrical power if it is not necessary (Ref 24-22-00/201).

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 ENGINE PROBE HEAT - DESCRIPTION AND OPERATION
_____________________________________________
 1.  General_______
 A.  Two engine probes (one for each engine) are electrically heated to prevent erroneous readings due to ice conditions. Engine probe heat system components consist of the engine probes. System electrical power comes from the main left and right 28v dc buses, and the main left and right 115v ac buses. Circuit breakers are on overhead circuit breaker panel P11.
 B.  The engine probes are identified as P1 probes and they will be referred to as the engine probes in this procedure.
 2.  Component Details (Fig. 1)_________________
P1 PROBE SEE A
P1 PROBE A
Engine Probe Heat Component Location Figure 1
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MAINTENANCE MANUAL

 A. Engine Probes
 (1)  
One engine probe is located on the upper inside surface of the inlet cowl. The probe measures total pressure in the inlet air stream entering the engine LP compressor.

 (2)  
The probe is heated by an electrical heating element which provides one level of heating. The heater uses 115v ac power.

 3. Operation (Fig. 2)
_________
 A. Functional Description
 (1)  
Engine probe heating is automatically controlled. This is done by action of air/ground relays and engine out relays whose position depends on outputs from engine proximity switches and speed cards.

 (2)  
On the ground, engine probe heating depends on engine speed from engine speed cards. If both engines are off, the engine out relays are de-energized. (The left and right engine out relays are in left miscellaneous relay panel P36 and right miscellaneous relay panel P37 respectively.) The circuit connecting power to the probes is open. The probes are not heated. This results in the Current Sensing Relay (CSR) associated with each engine probe to be de-energized. (The left and right CSR for the engine probes are in left miscellaneous relay panel P36 and right miscellaneous relay panel P37 respectively.)
　
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本文鏈接地址：757 AMM 飛機維護手冊 防冰和排雨 CHAPTER 30 - ICE AND RAIN PROTECTION(106)