APU AUTO SHUT DOWN - LOSS OF DC POWER, Low ECB Voltage (APS 3200)

TASK 49-00-81-810-879-A
APU AUTO SHUT DOWN - LOSS OF DC POWER, Low ECB Voltage (APS 3200)

1. Possible Causes

wiring
COOLING FAN/PMG ASSY (8055KM)
ELECTRONIC CONTROL BOX [59KD]
aircraft wiring
RELAY-APU MAIN CTL [4KD]
C/B-APU/ECB/SPLY [1KD]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
ESPM 2052210
ESPM 2053210
ESPM 205321A
AMM 49-00-00-710-008	Operational Test of the APU
AMM 49-52-53-000-001	Removal of the PMG and Cooling Fan Assembly (APS 3200)
AMM 49-52-53-400-001	Installation of the PMG and Cooling Fan Assembly (APS 3200)
ASM 496101
ASM 496102
AMM 49-61-34-000-002	Removal of the Electronic Control Box (ECB) (APS 3200)
AMM 49-61-34-400-002	Installation of the Electronic Control Box (ECB) (APS 3200)

3. Fault Confirmation
Subtask 49-00-81-710-208-A ** ON A/C NOT FOR ALL

A. Do the operational test of the APU AMM 49-00-00-710-008.

NOTE: This message is intermittent.
The ECB gives a LOSS OF DC POWER message if the electrical power stops for more than 230ms and then starts again.

4. Fault Isolation
Subtask 49-00-81-810-144-A ** ON A/C NOT FOR ALL

A. Maintenance Action
(1) If the APU SHUTDOWNS report gives the maintenance message:

LOSS OF DC POWER:
APU Auto Shut Down Fault Code Number: 040
Additionally the Last Leg Report gives the maintenance message:
COOLING FAN PMG ASSY (8055KM)
Fault Code Number: 002

do a check and repair the wiring from the ECB (59KD) AC10/11 to the PMG/Cooling Fan Assy Connector P28/2, 3 ASM 496102. ESPM 2052210 ESPM 2053210 ESPM 205321A.

(a) If the fault continues:

do a test of the PMG fuse with a multimeter (diode scale):
- place the positive lead on PIN 3 of P28 Connector and the negative lead on PIN 2.
- if it is approx. 0.9V, the fuse is OK.

1 If the fuse is OK:

replace the COOLING FAN/PMG ASSY (8055KM) AMM 49-52-53-000-001 and AMM 49-52-53-400-001.

a If the fault continues:

replace the ELECTRONIC CONTROL BOX [59KD] AMM 49-61-34-000-002 and AMM 49-61-34-400-002.

2 If the fuse is blown:

replace the ELECTRONIC CONTROL BOX [59KD] AMM 49-61-34-000-002 and AMM 49-61-34-400-002 and the COOLING FAN/PMG ASSY (8055KM) AMM 49-52-53-000-001 and AMM 49-52-53-400-001 at the same time.

(2) If the APU SHUTDOWNS report gives the maintenance message:

LOSS OF DC POWER:
APU Auto Shut Down Fault Code Number: 040

(a) If the fault is reproducible:

check the ELEC messages in the Last-Leg Report on the MCDU, and do the related Trouble-shooting.

1 If the fault continues:

do a check and repair the aircraft wiring between the ELECTRONIC CONTROL BOX [59KD] AC7 and the RELAY-APU MAIN CTL [4KD] A-A1 ASM 496101. ESPM 2052210 ESPM 2053210.

a If the fault continues:

do a check and repair the aircraft wiring between the RELAY-APU MAIN CTL [4KD] A-A2 and the C/B-APU/ECB/SPLY [1KD] ASM 496101. ESPM 2052210 ESPM 2053210.

b If the fault continues:

replace the ELECTRONIC CONTROL BOX [59KD] AMM 49-61-34-000-002 and AMM 49-61-34-400-002.

(b) If the fault is not reproducible:

No maintenance action is necessary.

Subtask 49-00-81-710-209-A ** ON A/C NOT FOR ALL

B. Do the test given in Para. 3.

[Rev.8 from Aug 2018] 2026.04.04 04:34:31 UTC