Failure of the Control of the Thrust-Reverser HCU Pressurizing-Valve through the Channel B on Engine 2

TASK 78-31-00-810-828-A
Failure of the Control of the Thrust-Reverser HCU Pressurizing-Valve through the Channel B on Engine 2

1. Possible Causes

HCU-THRUST REV (4101KS)
ECU [4000KS]
harness

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 71-50-00-210-001	Visual Inspection of the Power Plant Wire Harness
AMM 71-50-00-210-040	Visual Inspection of the Power Plant Wire Harnesses
AMM 71-51-43-000-049	Removal of the ECU (Channel A) to Thrust Reverser Junction Box Harnesses
AMM 71-51-43-400-049	Installation of the ECU (Channel A) to Thrust Reverser Junction Box Harnesses
AMM 71-51-44-000-002	Removal of the Thrust Reverser Harness 238W0908
AMM 71-51-44-400-002	Installation of the Thrust Reverser Harness 238W0908
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 732516
AMM 78-31-00-710-040	Operational Test of the Thrust Reverser System
AMM 78-31-00-710-042	Operational Test of the Thrust Reverser System
AMM 78-31-51-000-040	Removal of the Hydraulic Control Unit
AMM 78-31-51-000-042	Removal of the Hydraulic Control Unit
AMM 78-31-51-400-040	Installation of the Hydraulic Control Unit
AMM 78-31-51-400-042	Installation of the Hydraulic Control Unit

3. Fault Confirmation
Subtask 78-31-00-710-098-A ** ON A/C NOT FOR ALL

A. Do the operational test of the thrust reverser system (2B) AMM 78-31-00-710-040.

Subtask 78-31-00-710-098-B ** ON A/C NOT FOR ALL

A. Do the operational test of the thrust reverser system (2B) AMM 78-31-00-710-042.

4. Fault Isolation
Subtask 78-31-00-810-074-B ** ON A/C NOT FOR ALL

A. The fault message is generated when the ECU detects an open circuit or a short to ground on the solenoid of the HCU pressurizing valve on channel B or on associated electrical wiring.
(1) If the test gives the maintenance message HCU (TRPV), J6, ECU:

disconnect the harness J6 from the ECU (4000KS),
apply 28VDC between pin 17 (+) and pin 18 (-) on harness J6 and do a check of the value of the current, which must be between 350 and 630 mA ASM 732516.

(a) If the current is out of the specified values:

disconnect the channel B harness from the HCU-THRUST REV (4101KS) and do an insulation and continuity check of the harness J6 and thrust reverser harness between the ECU and the HCU connector B.

1 If there is a fault:

repair or replace the harness J6 or the thrust reverser harness or the junction box AMM 71-51-44-000-002 and AMM 71-51-44-400-002.

2 If nothing is found:

replace the HCU-THRUST REV (4101KS) AMM 78-31-51-000-040 and AMM 78-31-51-400-040.

(b) If the current is in the specified values:

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

(2) If the test does not give the maintenance message HCU (TRPV), J6, ECU, this indicates that the fault was intermittent and is no longer present:

do a check of the harness J6, the thrust reverser harness and the junction box for absence of damage AMM 71-50-00-210-040,
do a check of the connectors for looseness, contamination, bent pins.

(a) If damage is found:

clean, retighten or replace the harness as required AMM 71-51-44-000-002 and AMM 71-51-44-400-002.

(b) If no damage is found:

no additional action is required.

(3) If the fault message HCU (TRPV), J6, ECU becomes repetitive and is never confirmed during the operational test of the thrust reverser:

replace the HCU-THRUST REV (4101KS) AMM 78-31-51-000-040 and AMM 78-31-51-400-040.

(a) If the fault continues:

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

(b) If the fault continues:

replace the harness J6 and the thrust reverser harness AMM 71-51-44-000-002 and AMM 71-51-44-400-002.

Subtask 78-31-00-810-074-C ** ON A/C NOT FOR ALL

disconnect the harness J6 from the ECU (4000KS),
apply 28VDC between pin 17 (+) and pin 18 (-) on harness J6 and do a check of the value of the current, which must be between 350 and 630 mA ASM 732516.