Failure of the Thrust Reverser Hydraulic Isolation Valve in the Closed Position on Engine 1

TASK 78-31-00-810-855-A
Failure of the Thrust Reverser Hydraulic Isolation Valve in the Closed Position on Engine 1

1. Possible Causes

STATIC RELAY-THRUST REVERSER LOCKING CTL, ENG1 (3EG1)
RELAY-THRUST REVERSER LOCKING POWER, ENG1 (2EG1)
VALVE-THRUST REVERSER HYDRAULIC ISOLATION, ENG1 (50EG1)
HCU-THRUST REV (4101KS)
C/B-ENG1/REV/LOCK [1EG1]
C/B-ENGINE/ENG1/OIL/PRESS [2EN1]
SEC-1 [1CE1]
SEC-2 [1CE2]
PRESS SW-HCU [4102KS]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 27-94-34-000-001	Removal of the SEC
AMM 27-94-34-400-001	Installation of the SEC
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 78-31-16-000-040	Removal of the Hydraulic Control Unit Pressure Switch
AMM 78-31-16-000-041	Removal of the Hydraulic Control Unit Pressure Switch
AMM 78-31-16-400-040	Installation of the Hydraulic Control Unit Pressure Switch
AMM 78-31-16-400-041	Installation of the Hydraulic Control Unit Pressure Switch
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
AWM 783603
ASM 783701
AMM 78-37-51-000-001	Removal of the Thrust Reverser Hydraulic Isolation Valve
AMM 78-37-51-000-002	Removal of the Thrust Reverser Hydraulic Isolation Valve
AMM 78-37-51-400-001	Installation of the Thrust Reverser Hydraulic Isolation Valve
AMM 78-37-51-400-002	Installation of the Thrust Reverser Hydraulic Isolation Valve

3. Fault Confirmation
Subtask 78-31-00-865-050-A ** ON A/C NOT FOR ALL

A. Make sure that this(these) circuit breaker(s) is(are) closed:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
121VU	ENG1/REV/LOCK	1EG1	N44
121VU	ENGINE/ENG1/OIL/PRESS	2EN1	N40

Subtask 78-31-00-710-159-B ** ON A/C NOT FOR ALL

B. Test
(1) Do the operational test of the thrust reverser system (1A and 1B) (MENU mode test) AMM 78-31-00-710-040. Make sure that the hydraulic pressure is correct during the test. The pressure must not drop below the advisory threshold.

NOTE: If the test gives the maintenance message HCU, TRSOV, HYD or HCU (TRPV), HYD, do the test again with a hydraulic ground cart or do the operational test of the thrust reverser without CFDS with engine running AMM 78-31-00-710-040.
If you do the test with an engine ground run, enter a new flight number in the FMGC menu via the MCDU keypad to get a Post Flight Report (PFR) after the test.
If warning ENG 1 REVERSER FAULT and maintenance message HCU, TRSOV, HYD or HCU (TRPV), HYD are shown during the test, do the following trouble shooting. If they are not shown during the test or are not recorded in the Post Flight Report (PFR) after the ground run, no further action is required.

Subtask 78-31-00-710-159-D ** ON A/C NOT FOR ALL

B. Test
(1) Do the operational test of the thrust reverser system (1A and 1B) (MENU mode test) AMM 78-31-00-710-042. Make sure that the hydraulic pressure is correct during the test. The pressure must not drop below the advisory threshold.

Subtask 78-31-00-710-159-E ** ON A/C NOT FOR ALL

B. Test
(1) Make sure that the thrust reverser system is not mechanically deactivated (Inhibition pin on HCU).
(2) Do the operational test of the thrust reverser without CFDS with engine running AMM 78-31-00-710-040.

NOTE: Enter a new flight number in the FMGC menu via the MCDU keypad to get a Post Flight Report (PFR) after the test. If warning ENG 1 REVERSER FAULT and maintenance message HCU (TRPV), HYD are shown during the test, do the following trouble shooting. If they are not shown during the test or are not recorded in the Post Flight Report (PFR) after the ground run, no further action is required.

4. Fault Isolation
Subtask 78-31-00-810-110-B ** ON A/C NOT FOR ALL

A. This fault message is generated if the ECU detects no pressurization of the thrust reverser HCU after a deploy command of the thrust reverser. This indicates either a thrust reverser isolation valve failure to open or a HCU failure. The ECU cannot determine which one of the two items of equipment has failed as the thrust reverser isolation valve and the HCU are installed in series, while the ECU uses the HCU pressure switch for monitoring ASM 783701.

CAUTION: MAKE SURE THAT THERE IS NO HYDRAULIC PRESSURE WHILE YOU DO THIS TEST. PUT A WARNING NOTICE IN THE COCKPIT TO TELL PERSONS NOT TO PRESSURIZE THE HYDRAULIC SYSTEMS.

(1) If the test does not give the maintenance message HCU, TRSOV, HYD but the fault message is shown again on the subsequent flights:

replace the STATIC RELAY-THRUST REVERSER LOCKING CTL, ENG1 (3EG1).

(a) If the fault continues:

replace the RELAY-THRUST REVERSER LOCKING POWER, ENG1 (2EG1).

(2) If the test gives the maintenance message HCU, TRSOV, HYD or the thrust reverser blocker doors do not deploy normally or stow during the test:

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:

make sure that you have correctly exited the FADEC menu mode,
disconnect the electrical connector from the thrust reverser isolation valve (50EG1),
on the overhead panel 50VU, push and release the P/BSW-ENG/FADEC GND PWR/1 (7KS1) the ON legend comes on,
set the engine 1 throttle control lever to the reverse position. Make sure that the throttle control lever of the opposite engine is in the idle position,
do a check for ground at pin A/2 of the thrust reverser isolation valve (50EG1).

1 If there is no ground:

repair the wiring or the ground terminal 480VN1 AWM 783603.

2 If there is ground:

do a check for 115VAC between pins 1 and 2 of the connector on the harness side.

a If there is 115VAC:

replace the VALVE-THRUST REVERSER HYDRAULIC ISOLATION, ENG1 (50EG1) AMM 78-37-51-000-002 and AMM 78-37-51-400-002.
If the fault continues:
replace the HCU-THRUST REV (4101KS) AMM 78-31-51-000-040 and AMM 78-31-51-400-040.

b If there is no 115VAC:

on the overhead panel 50VU, push the P/BSW-ENG/FADEC GND PWR/1 (7KS1) the ON legend goes off,
do a continuity check of the electrical wiring between the thrust reverser isolation valve (50EG1) pin A/1 and the power relay 2EG1 pin A/A2.

c If the wiring is not correct:

repair as required.

d If the wiring is correct:

remove the static relay (3EG1) and the power relay (2EG1) from their base on 120VU.
on the overhead panel 50VU, push and release the P/BSW-ENG/FADEC GND PWR/1 (7KS1) the ON legend comes on,
with the engine 1 throttle control lever still in reverser position, do a check for 115VAC at pin A/B1 of the relay base 2EG1.

e If there is no 115VAC:

repair the wiring or replace the C/B-ENG1/REV/LOCK [1EG1] .

f If there is 115VAC:

do a check for 28VDC at pin A/X of the relay base 3EG1.

g If there is no 28VDC:

repair the wiring or replace the C/B-ENGINE/ENG1/OIL/PRESS [2EN1] .

h If there is 28VDC:

do a check for ground at pin A/X2 at the relay base 2EG1 and pin A/Z at the relay base 3EG1.

i If there is no ground:

repair the wiring.

j If there is ground:

on the overhead panel 50VU, push the P/BSW-ENG/FADEC GND PWR/1 (7KS1) the ON legend goes off,
set the engine 1 throttle control lever to idle position,
do a check of the wiring continuity between the static relay (3EG1), the SEC1 (1CE1) and the SEC2 (1CE2).

k If the wiring is correct:

make sure that there is no ground at pin AB/15E on the SEC1 (1CE1) and the SEC2 (1CE2) ASM 783701.
look for any FCDC or radio altimeter failure (on the Post Flight Report (PFR)) causing SEC output malfunction (TSM chapter 27).

l If no external failure to the SECs is found:

replace successively the SEC-1 [1CE1] then the SEC-2 [1CE2] AMM 27-94-34-000-001 and AMM 27-94-34-400-001.

(3) If thrust reverser operation (deploy and stow) was normal during aircraft operation and during the test but the test gives the maintenance message HCU, TRSOV, HYD or HCU (TRPV), HYD:

replace the PRESS SW-HCU [4102KS] AMM 78-31-16-000-040 and AMM 78-31-16-400-040.

(a) If the fault continues:

replace the HCU (4101KS1) AMM 78-31-51-000-040 and AMM 78-31-51-400-040.

Subtask 78-31-00-810-110-C ** ON A/C NOT FOR ALL

CAUTION: MAKE SURE THAT THERE IS NO HYDRAULIC PRESSURE WHILE YOU DO THIS TEST. PUT A WARNING NOTICE IN THE COCKPIT TO TELL PERSONS NOT TO PRESSURIZE THE HYDRAULIC SYSTEMS.

(1) If the test does not give the maintenance message HCU, TRSOV, HYD but the fault message is shown again on the subsequent flights:

replace the STATIC RELAY-THRUST REVERSER LOCKING CTL, ENG1 (3EG1).

(a) If the fault continues:

replace the RELAY-THRUST REVERSER LOCKING POWER, ENG1 (2EG1).

(2) If the test gives the maintenance message HCU, TRSOV, HYD or the thrust reverser blocker doors do not deploy normally or stow during the test:

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:

make sure that you have correctly exited the FADEC menu mode,
disconnect the electrical connector from the thrust reverser isolation valve (50EG1),
on the overhead panel 50VU, push and release the P/BSW-ENG/FADEC GND PWR/1 (7KS1) the ON legend comes on,
set the engine 1 throttle control lever to the reverse position. Make sure that the throttle control lever of the opposite engine is in the idle position,
do a check for ground at pin A/2 of the thrust reverser isolation valve (50EG1).

1 If there is no ground:

repair the wiring or the ground terminal 480VN1 AWM 783603.

2 If there is ground:

do a check for 115VAC between pins 1 and 2 of the connector on the harness side.

a If there is 115VAC:

replace the VALVE-THRUST REVERSER HYDRAULIC ISOLATION, ENG1 (50EG1) AMM 78-37-51-000-001 and AMM 78-37-51-400-001.
If the fault continues:
replace the HCU-THRUST REV (4101KS) AMM 78-31-51-000-042 and AMM 78-31-51-400-042.

b If there is no 115VAC:

on the overhead panel 50VU, push the P/BSW-ENG/FADEC GND PWR/1 (7KS1) the ON legend goes off,
do a continuity check of the electrical wiring between the thrust reverser isolation valve (50EG1) pin A/1 and the power relay 2EG1 pin A/A2.

c If the wiring is not correct:

repair as required.

d If the wiring is correct:

remove the static relay (3EG1) and the power relay (2EG1) from their base on 120VU.
on the overhead panel 50VU, push and release the P/BSW-ENG/FADEC GND PWR/1 (7KS1) the ON legend comes on,
with the engine 1 throttle control lever still in reverser position, do a check for 115VAC at pin A/B1 of the relay base 2EG1.

e If there is no 115VAC:

repair the wiring or replace the C/B-ENG1/REV/LOCK [1EG1] .

f If there is 115VAC:

do a check for 28VDC at pin A/X of the relay base 3EG1.

g If there is no 28VDC:

repair the wiring or replace the C/B-ENGINE/ENG1/OIL/PRESS [2EN1] .

h If there is 28VDC:

do a check for ground at pin A/X2 of the relay base 2EG1 and pin A/Z of the relay base 3EG1.

i If there is no ground:

repair the wiring.

j If there is ground:

on the overhead panel 50VU, push the P/BSW-ENG/FADEC GND PWR/1 (7KS1) the ON legend goes off,
set the engine 1 throttle control lever to idle position,
do a check of the wiring continuity between the static relay (3EG1), the SEC1 (1CE1) and the SEC2 (1CE2).

k If the wiring is correct:

make sure that there is no ground at pin AB/15E on the SEC1 (1CE1) and the SEC2 (1CE2) ASM 783701.
look for any FCDC or radio altimeter failure (on the Post Flight Report (PFR)) causing SEC output malfunction (TSM chapter 27).

l If no external failure to the SECs is found:

replace successively the SEC-1 [1CE1] then the SEC-2 [1CE2] AMM 27-94-34-000-001 and AMM 27-94-34-400-001.

(3) If thrust reverser operation (deploy and stow) was normal during aircraft operation and during the test but the test gives the maintenance message HCU, TRSOV, HYD or HCU (TRPV), HYD:

replace the PRESS SW-HCU [4102KS] AMM 78-31-16-000-041 and AMM 78-31-16-400-041.

(a) If the fault continues:

replace the HCU (4101KS1) AMM 78-31-51-000-042 and AMM 78-31-51-400-042.

Subtask 78-31-00-710-172-A ** ON A/C NOT FOR ALL

B. Do the test given in Para. 3.B.
(1) No additional maintenance action is required if the fault is not confirmed.
(2) Repeat the fault isolation procedure if the fault continues.

[Rev.8 from Aug 2018] 2026.04.04 04:38:03 UTC