Electrical Circuit Fault

TASK 21-43-00-810-819-A
Electrical Circuit Fault

1. Possible Causes

PUSHBUTTON SWITCH-CARGO HEATD/HOT AIR (16HC)
BOARD-ANN LT TEST & INTFC [11LP]
AFT CARGO HEAT CONTROLLER [10HC]
wiring

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
ASM 214302
AMM 21-43-34-000-002	Removal of the AFT Cargo Heat Controller
AMM 21-43-34-400-002	Installation of the AFT Cargo Heat Controller
AMM 21-61-00-710-001	Operational Test of the Pack Temperature-Control System
AMM 33-14-00-710-001	Operational Test of the Lights

3. Fault Confirmation
Subtask 21-43-00-710-084-A ** ON A/C NOT FOR ALL

A. Do the operational test of the pack temperature-control system AMM 21-61-00-710-001.

NOTE: The ZC (8HK) also monitors the cargo compartment heating system.

Subtask 21-43-00-710-084-D ** ON A/C NOT FOR ALL

A. Do the operational test of the pack temperature-control system AMM 21-61-00-710-001.

4. Fault Isolation
Subtask 21-43-00-810-077-A

A. If the test gives the maintenance message TEST OK, but the FAULT legend on the pushbutton switch CARGO HEAT/HOT AIR, which is installed on the CARGO HEAT panel 25VU, comes on:

do the operational test of the annunciator light test system AMM 33-14-00-710-001.

(1) If the operational test of the annunciator light test shows a fault:

do the trouble shooting of the annunciator light test system.

(2) If the operational test of the annunciator light test is correct:

do a check of the PUSHBUTTON SWITCH-CARGO HEATD/HOT AIR (16HC) and replace it if necessary ASM 214302.

(a) If the fault continues:

do a check of the BOARD-ANN LT TEST & INTFC [11LP] and replace it if necessary ASM 214302.

(b) If the fault continues:

replace the AFT CARGO HEAT CONTROLLER [10HC] AMM 21-43-34-000-002 and AMM 21-43-34-400-002.

do a check and repair the wiring between:
the RELAY (11LP) A/13 and SW (16HC) A/7,
the RELAY (11LP) A/14 and ACHC (10HC) AA/5A ASM 214302.

Subtask 21-43-00-710-085-A

B. Do the test given in Para. 3.

5. Close-up
Subtask 21-43-00-860-066-A

A. Put the aircraft back to its initial configuration.

[Rev.8 from Aug 2018] 2026.04.04 04:24:46 UTC