75-24-00
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CFM56 ENGINES
737-300/400/500/ /MAINTENANCE MANUAL ////////////////////////
D.  An orifice, located in the 9th-stage air extraction line between the valve and the compressor casing extraction manifold, reduces the 9th-stage air pressure being extracted to prevent 9th-stage air introduction into the 5th-stage of the compressor when both valves are open (during climb power).
 E.  When the engine is shut down, the two position hydraulic actuator valve rods are retracted, closing the 5th- and opening the 9th-stage air valves.
 F.  Actuation of the clearance control valve is controlled by three fuel pressure signals from the MEC. Two of the signals originate from turbine clearance valves (TC1 and TC2) which are positioned by the turbine clearance control valve (TCCV) scheduling cam as directed by the tach servo valve, which is a function of core engine speed (N2).
 G.  At selected speeds, TC1 and TC2 will provide outputs of either fuel bypass pressure, PB, or high servo pressure, PC. The third fuel pressure signal supplied from the MEC is intermediate servo pressure, PCR. Pressure relationship is PB < PCR < PC.
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CFM56 ENGINES
737-300/400/500/ /MAINTENANCE MANUAL ////////////////////////
HIGH PRESSURE TURBINE CLEARANCE CONTROL SYSTEM - ADJUSTMENT/TEST
________________________________________________________________
 1.  General
_______
 A.  This procedure contains an operation check for the
 High Pressure Turbine Clearance Control (HPTCC) Valve and Timer.

 NOTE: The HPTCC Timer must be active for the HPTCC Timer test.
____
 TASK 75-24-00-285-001-C00
 2.  Do the Check for the HPTCC Valve and Timer
__________________________________________
 A.  Equipment
 (1)  Actuation tester - HPTCC valve, 856A1353,
 CFM International, Cincinnati, Ohio 45246

 B.  References
 (1)  
AMM 71-00-00/201, Power Plant

 (2)  
AMM 71-11-02/201, Fan Cowl Panels

 (3)  
AMM 73-21-01/401, Main Engine Control (MEC)

 (4)  
AMM 75-24-01/401, High Pressure Turbine Clearance Control Valve

 (5)  
AMM 75-24-02/401, High Pressure Turbine Clearance Control Timer

 (6)  
AMM 78-31-00/201, Thrust Reversers

 C.  Access
 (1)  
Location Zones
 506 Engine No. 1 - Fan Frame
 606 Engine No. 2 - Fan Frame

 (2)  
Access Panels 5739L/5783L Thrust Reverser Half - Engine No. 1 5839R/5838R Thrust Reverser Half - Engine No. 2

 D.  Procedure
 S 865-002-C00
 CAUTION:_______DO NOT DO THIS CHECK ON AN ENGINE THAT IS WARM. THIS CAN RESULT IN UNSATISFACTORY CLEARANCES FOR THE BLADE TIPS AND CAUSE DAMAGE TO THE ENGINE.
 (1)  Make sure the engine is cool before you do this procedure.
 NOTE: A cool engine is one that is shut down for the night or is at
____ ground idle for a minimum of 10 minutes.
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CFM56 ENGINES
737-300/400/500/ /MAINTENANCE MANUAL ////////////////////////
S 015-003-C00
 (2)  
Open the fan cowl panel (AMM 71-11-02/201). S 015-004-C00

 EQUIPMENT CAN OCCUR.