Failure of the RACSB Valve on Engine 1

TASK 75-23-00-810-805-B
Failure of the RACSB Valve on Engine 1

1. Possible Causes

ECU [4000KS]
rotor active-clearance-control and Start Bleed (RACSB) valve
HMU
harness HJ7

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 73-21-10-000-002	Removal of the Hydromechanical Unit (HMU)
AMM 73-21-10-400-002	Installation of the Hydromechanical Unit (HMU)
AMM 73-21-50-000-040	Removal of the HJ7 Harness for SAC Engines
AMM 73-21-50-210-002	Visual Inspection of the Wiring Harnesses
AMM 73-21-50-400-040	Installation of the HJ7 Harness for SAC Engines
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)
AMM 73-29-00-710-040	Operational Test of the FADEC on the ground (with Engine Motoring)
AMM 75-23-10-000-002	Removal of the Rotor Active Clearance Start Bleed Valve
AMM 75-23-10-400-002	Installation of the Rotor Active Clearance Start Bleed Valve

3. Fault Confirmation
Subtask 75-23-00-710-078-A ** ON A/C NOT FOR ALL

A. Do the operational test of the FADEC 1A on the ground (with engine motoring) AMM 73-29-00-710-040.

4. Fault Isolation
Subtask 75-23-00-810-064-A ** ON A/C NOT FOR ALL

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

Disconnect the HJ7 harness fron the J7 receptacle on the ECU (4000KS). Make sure that the electrical contacts of the J7 receptacle are not bent or have not moved AMM 73-21-50-210-002.

(1) If you find damage:

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

(2) Do a resistance check of the RACSB valve circuits (channel A) through the HJ7 harness, 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 and Start Bleed (RACSB) valve AMM 75-23-10-000-002 and AMM 75-23-10-400-002.

1 If the fault continues:

replace the HMU AMM 73-21-10-000-002 and AMM 73-21-10-400-002.

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

disconnect the harness HJ7 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:

replace the defective harness HJ7 AMM 73-21-50-000-040 and AMM 73-21-50-400-040.

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

replace the HMU AMM 73-21-10-000-002 and AMM 73-21-10-400-002.

(3) If the fault continues:

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

Subtask 75-23-00-710-079-A ** ON A/C NOT FOR ALL

B. Do the test given in Para. 3.A.

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