AIR -TURBINE CASE COOLING (TCC) SYSTEM -GENERAL DESCRIPTION

EFFECTIVITY BEJ ALL  75-24-00 
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D633W101-BEJ  Sep 05/2002 

AIR -TCC SYSTEM -AIR VALVE ACTUATOR AND CONTROL CABLES

TCC Air Valve Actuator
The TCC air valve actuator uses the push-pull control cables to mechanically modulate the TCC HPT or TCC LPT air valve.
There are two piston actuators in the same housing. The EEC electrically controls the torque motor for each. Servo fuel pressure moves the piston actuator.
The TCC air valve actuator is on the forward part of the HPC case at the 2:00 position. You open the right thrust reverser to get access to the TCC air valve actuator.
TCC Air Valve Control Cables
A TCC air valve control cable connects each air valve to the TCC air valve actuator. Each control cable is in a hard sheath. The rod end of the cable is adjustable.
The two cables attach to brackets on the HPC case at the 2:00 position. You open the right thrust reverser to get access to the TCC air valve control cables.
Training Information Point
If you replace the TCC air valve actuator, TCC control cables, or a TCC air valve, you must rig the TCC system.
EFFECTIVITY BEJ ALL  75-24-00 
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D633W101-BEJ  Sep 05/2002 

AIR -TCC SYSTEM -AIR VALVE ACTUATOR AND CONTROL CABLES

EFFECTIVITY BEJ ALL  75-24-00 
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D633W101-BEJ  Sep 05/2002 

AIR -TCC SYSTEM -HPT AND LPT AIR VALVES

Purpose
The TCC HPT air valve and the TCC LPT air valve control the flow of fan air that cools the HPT and LPT cases.
Location
The air valves attach to their collectors on the turbine case at the 2:00 position. You must open the right thrust reverser to get access to the valves.
TCC HPT and LPT Air Valves
Each TCC air valve is a butterfly-type modulating valve. The TCC air valve control cables attach to the valve linkages.
A spring holds the HPT air valve in the closed position. A spring holds the LPT air valve in a not fully closed position. Each valve has a rig pin hole.
Training Information Point
You must remove the LPT valve before you replace the HPT valve.
EFFECTIVITY BEJ ALL  75-24-00 
Page 6 
D633W101-BEJ  Sep 05/2002 

PW4000 SERIES ENGINES

777 AIRCRAFT MAINTENANCE MANUAL

AIR -TCC SYSTEM -HPT AND LPT AIR VALVES

EFFECTIVITY BEJ ALL  75-24-00 
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D633W101-BEJ  Sep 05/2002 

AIR -TCC SYSTEM -FUNCTIONAL DESCRIPTION

General
The EEC uses altitude and HPC rotor speed (N2) to control the HPT and LPT TCC air valves. This controls the flow of fan air to cool the outside of the HPT and LPT cases.
　
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