PHMU Internal Sensor Interface Fault

TASK 77-31-00-810-807-A
PHMU Internal Sensor Interface Fault

1. Possible Causes

PROGNOSTICS AND HEALTH MANAGEMENT UNIT [4609KS]

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 24-41-00-861-002	Energize the Aircraft Electrical Circuits from the External Power
AMM 24-41-00-862-002	De-energize the Aircraft Electrical Circuits Supplied from the External Power
AMM 71-13-00-010-802	Opening of the Fan Cowl Doors
AMM 71-13-00-410-802	Closing of the Fan Cowl Doors
AMM 77-31-01-000-801	Removal of the Prognostics and Health Management Unit (PHMU)
AMM 77-31-01-400-801	Installation of the Prognostics and Health Management Unit (PHMU)
EEC and PHMU Wiring Harnesses

3. Fault Confirmation
Subtask 77-31-00-710-056-A ** ON A/C NOT FOR ALL

A. Energize the FADEC of the engine that has a fault report.
(1) Energize the aircraft electrical circuits AMM 24-41-00-861-002.
(2) On the ENG section of maintenance panel 50VU:
(a) Release the FADEC GND PWR/1(2) pushbutton switch (the ON legend comes on).

NOTE: After the FADEC is energized, wait ten seconds before you start the test. If you do not wait ten seconds, the interactive mode stops the EEC self-test and this can cause spurious faults.

(3) On Multipurpose Control and Display Unit (MCDU) screen, check if the fault is displayed on ground scanning report.

NOTE: The Electronic Engine Control (EEC) channel A or channel B is reporting that the Prognostic and Health Management Unit (PHMU) has an internal fault. The PHMU is located on the fan case adjacent to the EEC at the 2 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).

(4) If the maintenance message does not come back, examine the harnesses and electrical connectors as described in the component and harness intermittent fault isolation procedure (Ref. TSM TASK 71-00-00-810-835).
(a) If no problems are found, return the engine to service. Monitor the engine for reoccurring maintenance message.
(5) If the maintenance message comes back (hard fault), 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.

CAUTION: MAKE SURE YOU REMOVE ELECTRICAL POWER FROM THE EEC BEFORE YOU REMOVE THE ELECTRICAL CONNECTORS. IF YOU DO NOT OBEY THIS INSTRUCTION, DAMAGE TO THE EEC CAN OCCUR.

Subtask 77-31-00-810-056-A ** ON A/C NOT FOR ALL

A. If there is confirmation of the fault:
(1) Open the fan cowl doors AMM 71-13-00-010-802.
(2) Replace PROGNOSTICS AND HEALTH MANAGEMENT UNIT [4609KS] AMM 77-31-01-000-801 and AMM 77-31-01-400-801.
(a) Do the test given in Para. 3.

5. Close-up
Subtask 77-31-00-860-056-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 fan cowl doors AMM 71-13-00-410-802.
(b) De-energize the aircraft electrical circuits AMM 24-41-00-862-002.

[Rev.8 from Aug 2018] 2026.04.04 04:37:58 UTC