Failure of the RACC Valve on Engine 2

TASK 75-23-00-810-818-A
Failure of the RACC Valve on Engine 2

1. Possible Causes

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 73-21-50-000-007	Removal of J8 Harness
AMM 73-21-50-400-007	Installation of the J8 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 75-23-10-000-001	Removal of the Rotor Active Clearance Control (RACC) Valve
AMM 75-23-10-400-001	Installation of the Rotor Active Clearance Control (RACC) Valve

3. Fault Confirmation
Subtask 75-23-00-710-098-A ** ON A/C NOT FOR ALL

A. Do the operational test of the FADEC 2B on the ground (with engine motoring) AMM 73-29-00-710-040.

NOTE: If post SB 75-029, fault message must be ignored: no trouble shooting is necessary.

4. Fault Isolation
Subtask 75-23-00-810-075-A ** ON A/C NOT FOR ALL

A. If the test gives the maintenance message RAC VLV, HMU:

do a check for line to line short circuit of the torque motor circuit of the rotor active-clearance-control (RACC) system ASM 732518.

(1) If the wiring is not correct:

(2) If the wiring is correct:

disconnect the harness J8 from the ECU (4000KS) and do a check of the resistance of the cable between:
. pins 20 and 40 (17 to 23 ohms).

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

replace the rotor active-clearance-control (RACC) valve AMM 75-23-10-000-001 and AMM 75-23-10-400-001.

1 If the fault continues:

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

disconnect the harness J8 from the HMU and do a check of the resistance of the HMU between:
. pins 20 and 40 (17 to 23 ohms).

1 If the resistance values are in the specified limits:

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

(3) If the fault continues:

Subtask 75-23-00-810-075-C ** ON A/C NOT FOR ALL

A. If the test gives the maintenance message RAC VLV, (POS) HMU:

do a check for line to line chort circuit of the torque motor circuit of the rotor active-clearance-control (RACC) system ASM 732518.