APU AUTO SHUTDOWN - REVERSE FLOW, SCV Position disagrees with Command (131-9(A))

TASK 49-00-81-810-848-A
APU AUTO SHUTDOWN - REVERSE FLOW, SCV Position disagrees with Command (131-9(A))

1. Possible Causes

SCV POSITION DISAGREES WITH COMMAND
damage/leakage of the fuel supply and return lines
SURGE CONTROL VALVE (P18)
ELECTRONIC CONTROL BOX [59KD]
SURGE CONTROL VALVE (8058KM)

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 49-00-00-860-008	APU Start by External Power
AMM 49-51-52-000-003	Removal of the Surge Control Valve (131-9(A))
AMM 49-51-52-400-003	Installation of the Surge Control Valve (131-9(A))
AMM 49-61-34-000-003	Removal of the Electronic Control Box (ECB) (131-9(A))
AMM 49-61-34-400-003	Installation of the Electronic Control Box (ECB) (131-9(A))

3. Fault Confirmation
Subtask 49-00-81-710-186-A ** ON A/C NOT FOR ALL

A. Read-out of ECB Trouble-Shooting Data
(1) Put the APU MASTER SW to the ON position.
(2) Get access to the APU SHUTDOWN report.
(3) Push the '>' adjacent to LRU DATA:

the MCDU menu shows
SCV POSITION DISAGREES WITH COMMAND

(4) Start the APU and apply Bleed Air for 20 seconds, minimum AMM 49-00-00-860-008.

4. Fault Isolation
Subtask 49-00-81-810-129-A ** ON A/C NOT FOR ALL

A. If an APU auto shutdown occurs during the APU operation and the APU SHUTDOWN report gives the maintenance message:

REVERSE FLOW
SURGE CONTROL VALVE P18

associated with Fault Code Numbers (FCN) 87

do a check of damage/leakage of the fuel supply and return lines of the SURGE CONTROL VALVE (P18).

(1) If there is damaged/leaking in the fuel supply and return lines:

do a repair.

(2) If the fuel supply and return lines are OK:

replace the SURGE CONTROL VALVE (P18) AMM 49-51-52-000-003 and AMM 49-51-52-400-003.

(a) If the fault continues:

replace the ELECTRONIC CONTROL BOX [59KD] AMM 49-61-34-000-003 and AMM 49-61-34-400-003.

Subtask 49-00-81-810-129-B ** ON A/C NOT FOR ALL

A. If an APU auto shutdown occurs during the APU operation and the APU SHUTDOWN report gives the maintenance message:

REVERSE FLOW
SURGE CONTROL VALVE (8058KM)

associated with Fault Code Numbers (FCN) 87

do a check of damage/leakage of the fuel supply and return lines of the SURGE CONTROL VALVE (8058KM)

(1) If there is damaged/leaking in the fuel supply and return lines:

do a repair.

(2) If the fuel supply and return lines are OK:

replace the SURGE CONTROL VALVE (8058KM) AMM 49-51-52-000-003 and AMM 49-51-52-400-003.

(a) If the fault continues:

replace the ELECTRONIC CONTROL BOX [59KD] AMM 49-61-34-000-003 and AMM 49-61-34-400-003.

Subtask 49-00-81-710-187-A ** ON A/C NOT FOR ALL

B. Do the test given in Para. 3.

[Rev.8 from Aug 2018] 2026.04.04 04:34:35 UTC