Failure of the HPTCC Valve on Engine 2

TASK 75-21-00-810-802-A
Failure of the HPTCC Valve on Engine 2

1. Possible Causes

High Pressure Turbine Clearance Control (HPTCC) valve
HMU-2 [4000KC2]
ECU [4000KS]
harness J7

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 73-21-10-000-001	Removal of the Hydromechanical Unit (HMU)
AMM 73-21-10-400-001	Installation of the Hydromechanical Unit (HMU)
AMM 73-21-50-000-006	Removal of J7 Harness
AMM 73-21-50-400-006	Installation of the J7 Harness
AMM 73-21-60-000-001	Removal of the Electronic Control Unit (ECU)
AMM 73-21-60-400-001	Installation of the Electronic Control Unit (ECU)
ASM 732518
AMM 73-29-00-710-040	Operational Test of the FADEC on the ground (with Engine Motoring)
AMM 75-21-10-000-001	Removal of the High Pressure Turbine Active Clearance Control (HPTACC) Valve
AMM 75-21-10-400-001	Installation of the High Pressure Turbine Active Clearance Control (HPTACC) Valve

3. Fault Confirmation
Subtask 75-21-00-710-052-A ** ON A/C NOT FOR ALL

A. Test
(1) Do the operational test of the FADEC 2A on the ground (with engine motoring) AMM 73-29-00-710-040.
(2) Read the TROUBLE SHOOTING DATA of the FADEC MENU on the MCDU (Ref. 70-00-00, P. Block 301).

4. Fault Isolation
Subtask 75-21-00-810-052-A ** ON A/C NOT FOR ALL

A. If the test gives the maintenance message HPTC VLV, HMU and the TROUBLE SHOOTING DATA gives the complementary information HPTC VLV BLEED ACTUATION:

replace the High Pressure Turbine Clearance Control (HPTCC) valve AMM 75-21-10-000-001 and AMM 75-21-10-400-001.

(1) If the fault continues:

replace the HMU-2 [4000KC2] AMM 73-21-10-000-001 and AMM 73-21-10-400-001.

(2) If the fault continues:

replace the ECU [4000KS] AMM 73-21-60-000-001 and AMM 73-21-60-400-001.

Subtask 75-21-00-810-053-A ** ON A/C NOT FOR ALL

B. If the test gives the maintenance message HPTC VLV, HMU and the TROUBLE SHOOTING DATA gives the complementary information HPTC VLV ACTUATION:

do a check for open or short to ground of the harness J7 between the ECU (4000KS) and the torque motor of the HPT active clearance control system ASM 732518.

(1) If the fault continues:

disconnect the cable J7 from the ECU and do a check of the ECU cable resistance between:
. pins 23 and 24 (17 to 23 Ohms).

(a) If the resistance values are in the specified limits:

replace the High Pressure Turbine Clearance Control (HPTCC) valve AMM 75-21-10-000-001 and AMM 75-21-10-400-001.

(b) If the resistance values are out of the specified limits:

disconnect the cable J7 from the HMU and do a check of the HMU resistance between:
. pins 23 and 24 (17 to 23 Ohms).

1 If the resistance values are in the specified limits:

replace the defective harness J7 AMM 73-21-50-000-006 and AMM 73-21-50-400-006.

2 If the resistance values are out of the specified limits:

replace the HMU-2 [4000KC2] AMM 73-21-10-000-001 and AMM 73-21-10-400-001.

(2) If the resistance checks are correct and if the replacement of the HPTCC valve does not correct the fault:

replace the HMU-2 [4000KC2] AMM 73-21-10-000-001 and AMM 73-21-10-400-001.

(3) If the fault continues:

replace the ECU [4000KS] AMM 73-21-60-000-001 and AMM 73-21-60-400-001.

Subtask 75-21-00-710-053-A ** ON A/C NOT FOR ALL

C. Do the test given in Para. 3.A.(1).

[Rev.8 from Aug 2018] 2026.04.04 04:37:01 UTC