HPC Bleed Valve Failed Closed during Engine Starting

TASK 75-32-00-810-838-A
HPC Bleed Valve Failed Closed during Engine Starting

1. Possible Causes

HPC BLEED VALVE [4102JM]
HPC BLEED VALVE AIR PRESSURE SENSOR [4058KS]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
TSM TASK 71-00-00-810-834-A	General Troubleshooting Guidelines for Additional Troubleshooting Information
TSM TASK 71-00-00-810-835-A	Component and Harness Intermittent Troubleshooting Procedure for Guidance Troubleshooting Intermittent Faults
AMM 71-00-00-860-814	Shutdown of the Engine
AMM 71-00-00-860-822	Start the Engine (Normal Manual Start)
AMM 71-00-00-860-823	Start the Engine (Normal Automatic Start)
AMM 75-32-02-000-801	Removal of the HPC Bleed Valve
AMM 75-32-02-400-801	Installation of the HPC Bleed Valve
AMM 75-32-21-000-801	Removal of the HPC Bleed Valve Air Pressure Sensor (Passive)
AMM 75-32-21-400-801	Installation of the HPC Bleed Valve Air Pressure Sensor (Passive)
AMM 78-36-00-010-802	Opening of the Thrust Reverser Cowl-Doors
AMM 78-36-00-410-802	Closing of the Thrust Reverser Cowl-Doors
Passive HPC Bleed Valve

3. Fault Confirmation
Subtask 75-32-00-710-094-A ** ON A/C NOT FOR ALL

A. Do an engine run to idle to confirm repair of this fault AMM 71-00-00-860-822 or AMM 71-00-00-860-823.
(1) Shutdown the engine AMM 71-00-00-860-814.
(2) On MCDU screen, check if the fault is displayed on ground scanning report.

NOTE: The Electronic Engine Control (EEC) channel A and channel B have detected that the passive High Pressure Compressor (HPC) bleed valve is failed in the closed position. The EEC determines passive HPC bleed valve position by monitoring the passive HPC bleed valve air pressure sensor. The passive HPC bleed valve is mounted on the diffuser case located at the 12 o'clock position. The passive HPC bleed valve air pressure sensor is attached to the compressor intermediate case firewall located at the 10 o'clock position.

Refer to the general troubleshooting guidelines for additional troubleshooting information (Ref. TSM TASK 71-00-00-810-834).
Refer to the component and harness intermittent troubleshooting procedure for guidance troubleshooting intermittent faults (Ref. TSM TASK 71-00-00-810-835).

NOTE: The passive HPC bleed valve will move to its closed position during the start cycle when the HPC bleed pressure becomes high enough to push the bleed valve to the closed position. If the bleed valve is stuck in the closed position or moves to the closed position earlier than expected, a failed start or extended start time may result.

(3) If the maintenance message does not come back, inspect around the passive HPC bleed valve for material or conditions which could limit the movement of the bleed valve.
(a) If no problems are found, return the engine to service. Monitor the engine for reoccurring maintenance message. Continue with the hard fault troubleshooting below if the fault returns.
(4) If the maintenance message comes back (hard fault) in channel A and channel B, go to the Para. Fault Isolation.

4. Fault Isolation

WARNING: BE CAREFUL WHEN YOU DO WORK ON THE ENGINE AFTER SHUTDOWN. THE ENGINE CAN STAY HOT FOR A LONG TIME. IF YOU DO NOT OBEY THIS WARNING, INJURY CAN OCCUR.

WARNING: REFER TO THE MSDS FOR ALL MATERIAL USED AND THE MANUFACTURER'S SAFETY INSTRUCTIONS FOR ALL EQUIPMENT USED. IF YOU DO NOT OBEY THIS WARNING, INJURY CAN OCCUR.

Subtask 75-32-00-810-096-A ** ON A/C NOT FOR ALL

A. If there is confirmation of the fault:
(1) Open the thrust reverser cowl-doors AMM 78-36-00-010-802.
(2) Inspect around the passive HPC bleed valve for material or conditions which could limit the movement of the bleed valve.
(3) Inspect the passive HPC bleed valve air pressure sense line (AS33) from the passive HPC bleed valve to the passive HPC bleed valve air pressure sensor for conditions which could block airflow.
(a) Look for dents and loose connectors.
(b) Examine the weep hole in the water trap below the passive HPC bleed valve air pressure sensor connection for blockage.

NOTE: Low pressure compressed air may be blown through the passive HPC bleed valve air pressure sense line (AS33) to verify it is clear. Remove the passive HPC bleed valve air pressure sense line (AS33) from the passive HPC bleed air pressure sensor and blow air into the passive HPC bleed valve air pressure sense line (AS33). Do not blow compressed air into the pressure sensor or damage to the pressure sensor may result.

(4) Repair any problems found.
(5) Do the test given in Para. 3.
(6) If no problems are found or the fault continues:
(a) Replace HPC BLEED VALVE [4102JM] AMM 75-32-02-000-801 and AMM 75-32-02-400-801.
(b) Do the test given in Para. 3.
(7) If the fault continues:
(a) Replace HPC BLEED VALVE AIR PRESSURE SENSOR [4058KS] AMM 75-32-21-000-801 and AMM 75-32-21-400-801.
(b) Do the test given in Para. 3.

5. Close-up
Subtask 75-32-00-860-057-A ** ON A/C NOT FOR ALL

A. Put the aircraft back to its initial configuration.
(1) Make sure that the work area is clean and clear of tools and other items.
(a) Close the thrust reverser cowl-doors AMM 78-36-00-410-802.

[Rev.8 from Aug 2018] 2026.04.04 04:37:22 UTC