Failure of the APU Boost on Engine 1

TASK 73-25-00-810-867-A
Failure of the APU Boost on Engine 1

1. Possible Causes

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 49-61-34-000-001	Removal of the Electronic Control Box (ECB) (GTCP 36-300)
AMM 49-61-34-000-002	Removal of the Electronic Control Box (ECB) (APS 3200)
AMM 49-61-34-000-003	Removal of the Electronic Control Box (ECB) (131-9(A))
AMM 49-61-34-400-001	Installation of the Electronic Control Box (ECB) (GTCP 36-300)
AMM 49-61-34-400-002	Installation of the Electronic Control Box (ECB) (APS 3200)
AMM 49-61-34-400-003	Installation of the Electronic Control Box (ECB) (131-9(A))
ASM 732509
AMM 73-25-34-000-040	Removal of the Engine Interface Unit (EIU)
AMM 73-25-34-400-040	Installation of the Engine Interface Unit (EIU)
AMM 73-25-34-710-040	Operational Test of the Engine Interface Unit
AMM 73-25-34-710-043	Operational Test of the Engine Interface Unit

3. Fault Confirmation
Subtask 73-25-00-710-182-A ** ON A/C NOT FOR ALL

A. Do the operational test of the engine interface unit through the CFDS AMM 73-25-34-710-040.

Subtask 73-25-00-710-182-B ** ON A/C NOT FOR ALL

A. Do the operational test of the engine interface unit through the CFDS AMM 73-25-34-710-043.

4. Fault Isolation
Subtask 73-25-00-810-116-A ** ON A/C NOT FOR ALL

A. If the test gives the maintenance message CHECK ECB (59KD)/EIU CIRCUIT OR EIU1:

Do a check to make sure that the APU is boosted during the engine start sequence when the starter shutoff valve is open.

(1) If the APU is boosted:

(2) If the APU is not boosted:

Do a check and repair the wiring from EIU-1 (1KS1) to the ECB (59KD), pin AB/1C to pin AB/E5 ASM 732509 and ASM 732509.

(a) If the fault continues, replace the ELECTRONIC CONTROL BOX [59KD] :

(b) If the fault continues:

Replace the RELAY-CTR TK PUMPS 1 CTL [51QA] or the RELAY-CTR TK PUMPS 2 CTL [52QA] .

Subtask 73-25-00-810-116-B ** ON A/C NOT FOR ALL

A. If the test gives the maintenance message CHECK ECB (59KD)/EIU CIRCUIT OR EIU1:

Do a check to make sure that the APU is boosted during the engine start sequence when the starter shutoff valve is open.

(1) If the APU is boosted:

(2) If the APU is not boosted:

Do a check and repair the wiring from EIU-1 (1KS1) to the ECB (59KD), pin AB/1C to pin AB/E5 ASM 732509 and ASM 732509.

(a) If the fault continues, replace the ELECTRONIC CONTROL BOX [59KD] :

(b) If the fault continues:

Replace the RELAY-CTR TK PUMPS 1 CTL [51QA] or the RELAY-CTR TK PUMPS 2 CTL [52QA] .

Subtask 73-25-00-710-183-A ** ON A/C NOT FOR ALL

B. Do the test given in Para. 3.A.

[Rev.8 from Aug 2018] 2026.04.04 04:35:44 UTC