Failure of the T/R Hydraulic Isolation Valve in the open position on the Engine 1

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1. Possible Causes
· VALVE-THRUST REVERSER HYDRAULIC ISOLATION, ENG1 (50EG1)
· STATIC RELAY-THRUST REVERSER LOCKING CTL, ENG1 (3EG1)
· RELAY-THRUST REVERSER LOCKING POWER, ENG1 (2EG1)
· SEC-1 ( 1CE1 )
· SEC-2 ( 1CE2 )
2 Job Set-up Information
A. Referenced Information
REFERENCE DESIGNATION
Ref. AMM 27-94-34-000-001 Removal of the SEC
Ref. AMM 27-94-34-400-001 Installation of the SEC
Ref. AMM 78-31-00-710-041 Operational Test of the Thrust Reverser System with the CFDS
Ref. ASM 78-37-01
Ref. AMM 78-37-51-000-010 Removal of the Thrust Reverser Hydraulic Isolation Valve
Ref. AMM 78-37-51-400-010 Installation of the Thrust Reverser Hydraulic Isolation Valve
3. Fault Confirmation
Subtask 78-37-00-865-052-A
A. Table of the circuit breakers used in this procedure:
PANEL DESIGNATION FIN LOCATION
121VU ENG1/REV/LOCK 1EG1 N44
Subtask 78-37-00-710-054-A
B. Test
(1) Pull the circuit breaker 1EG1 and do the operational test of the thrust reverser system (1A and 1B)
Ref. AMM 78-31-00-710-041 .
4. Fault Isolation
Subtask 78-37-00-810-052-A
A. The fault message is generated if the EEC detects a pressurization of the thrust reverser HCU during the
thrust reverser isolation valve monitoring test after the engine start. The message indicates that the thrust
reverser isolation valve has failed in the open position or is leaking internally.
(1) If the thrust reverser opens during the test:
· replace the VALVE-THRUST REVERSER HYDRAULIC ISOLATION, ENG1 (50EG1) Ref.
AMM 78-37-51-000-010 and Ref. AMM 78-37-51-400-010 .
(2) If the thrust reverser does not open during the test:
· look for the cause of abnormal permanent electrical supply of the thrust reverser isolation valve or
undue fault annunciation as follows Ref. ASM 78-37-01,
· replace the STATIC RELAY-THRUST REVERSER LOCKING CTL, ENG1 (3EG1) .
(a) If the fault continues:
· replace the RELAY-THRUST REVERSER LOCKING POWER, ENG1 (2EG1) .
(b) If the fault continues:
· remove the static relay (3EG1) from its base on shelf 120VU and do a check for permanent
ground at pin A/1.
1 If there is ground:
· do a check for short to ground between the SEC1 (1CE1), the SEC2 (1CE2) and the static
relay (3EG1).
a If the wiring is not correct:
· repair as required.
b If the wiring is correct:
· do the trouble shooting of the SEC1 (1CE1) and the SEC2 (1CE2) for abnormal
ground at pin AB/15E on the SEC1 (1CE1) and at pin AB/15E on the SEC2 (1CE2)
Ref. ASM 78-37-01,
· look for any FCDC or radio altimeter failure (in Post Flight Report (PFR)) causing SEC
output malfunction (TSM chapter 27).
. If no external failure to the SECs is found:
· replace successively the SEC-1 ( 1CE1 ) then the SEC-2 ( 1CE2 ) Ref.
AMM 27-94-34-000-001 and Ref. AMM 27-94-34-400-001 .
Subtask 78-37-00-865-060-A
B. Make sure that this(these) circuit breaker(s) is(are) closed:
PANEL DESIGNATION FIN LOCATION
121VU ENG1/REV/LOCK 1EG1 N44
Subtask 78-37-00-710-055-A
C. Check that the warning and failure message do not duplicate at next engine start. [Rev.6 from Feb 2017] 2026.04.04 04:38:20 UTC