PPRuNe Forums - View Single Post - HPTCC: High Pressure Turbine Clearance Control
Old 13th Aug 2007, 16:30
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tom775257
 
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I have the presentation from CFM, with the data related to the CFM56-5B (full FADEC) on the Airbus 320. It says the HPTCC uses HPC 4th and 9th stage bleed air. The graph shows that in cruise there is the highest airflow through the 4th Stage HPTCC air supply to the turbine casing. At full power there is the greatest amount of airflow from the 9th stage.

This is controlled by the ECU, which in turn uses the HMU to supply servo fuel to control the valve position.

There is also the following statement:

No air: Both butterfly valves closed: Failsafe position
9th Stage: 9th stage valve open only: Idle, takeoff, start.
Mixed: Both butterfly valves open: Climb.
4th stage: Only 4th stage open: Cruise.

By the way there is also low pressure turbine clearance control using fan air.

All the best.
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