Difference in Current between the IDG 1 Current Transformer and the AC Current Transformer 1

TASK 24-22-00-810-802-A
Difference in Current between the IDG 1 Current Transformer and the AC Current Transformer 1

1. Possible Causes

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 24-21-51-000-040	Removal of the Integrated Drive Generator - IDG 1(2)
AMM 24-21-51-400-040	Installation of the Integrated Drive Generator - IDG 1(2)
ASM 242201
AMM 24-22-17-000-001	Removal of the AC Current Transformers
AMM 24-22-17-400-001	Installation of the AC Current Transformers
AMM 24-22-34-000-001	Removal of the GCU-1(2)
AMM 24-22-34-400-001	Installation of the GCU-1(2)
AMM 24-41-00-740-004	Operational Check of the GPCU via the CFDS

3. Fault Confirmation
Subtask 24-22-00-710-050-A ** ON A/C NOT FOR ALL

A. Test
Do the operational test of the GPCU and do the check of class 3 faults of the GPCU from the CFDS AMM 24-41-00-740-004.

4. Fault Isolation
Subtask 24-22-00-810-051-B ** ON A/C NOT FOR ALL

A. If the test gives the maintenance message CHECK GCU1 PIN B11D, B13D:

Remove the GCU-1 (1XU1) AMM 24-22-34-000-001.
On the connector AB of the GCU-1 (1XU1), connect together the pins AB/13A to AB/13D ASM 242201.
Do an insulation check between the pins AB/13A to AB/13D of the GCU-1 (1XU1) and the ground.

(1) If the insulation check is correct:

On the connector AB of the GCU-1 (1XU1), disconnect the pins AB/13A to AB/13D and connect together the pins AB/11A to AB/11D ASM 242201.
Do an insulation check between the pins AB/11A to AB/11D of the connector AB of the GCU-1 (1XU1) and the ground:

(a) If the insulation check is correct:

(b) If the insulation check is not correct:

On the connector AB of the GCU-1 (1XU1), disconnect the pins AB/11A to AB/11D.
Disconnect the connector A of the AC current transformer 1 (42XU1) ASM 242201.
On the AC current transformer 1 (42XU1), connect together the pins A/1 to A/4.
Do an insulation check between the pins A/1 to A/4 of the AC current transformer 1 (42XU1) and the ground.

1 If the insulation check is not correct:

2 If the insulation check is correct:

Disconnect the connector A of the AC current transformer 1 (42XU3) ASM 242201.
On the AC current transformer 1 (42XU3), connect together the pins A/1 to A/4.
Do an insulation check between the pins A/1 to A/4 of the AC current transformer 1 (42XU3) and the ground.

a If the insulation check is not correct:

b If the insulation is correct, do an insulation check between:

The ground and, in sequence, the pins AB/11A, AB/11B, AB/11C, AB/11D of the connector AB of the GCU-1 (1XU1) and repair the wiring .
Connect the connectors A of the AC current transformer 1 (42XU1) and the AC current transformer 1 (42XU3).
Install the GCU-1 (1XU1) AMM 24-22-34-400-001.

(2) If the insulation check is not correct:

Disconnect the connector A of the engine IDG 1 (4000XU1).
On the engine IDG 1 (4000XU1), connect together the pins A/1, A/6 to A/8.
Do an insulation check between the pins A/1, A/6 to A/8 of the engine IDG 1 (4000XU1) and the ground.

(a) If the insulation check is not correct:

(b) If the insulation check is correct:

On the connector AB of the GCU-1 (1XU1), disconnect the pins AB/13A to AB/13D ASM 242201.

1 Do an insulation check between:

The ground and, in sequence, the pins AB/13A, AB/13B, AB/13C, AB/13D of the connector AB of the GCU-1 (1XU1) and repair the wiring .

2 Connect the connector A of the engine IDG 1 (4000XU1).
3 Install the GCU-1 (1XU1) AMM 24-22-34-400-001.

Subtask 24-22-00-700-050-A ** ON A/C NOT FOR ALL

B. When you replace a component or repair the wiring:

do the subsequent flight before you do the test given in Para. 3. to make sure that the system operates correctly.
If the test continues to give the fault message, continue the trouble shooting procedure.

[Rev.8 from Aug 2018] 2026.04.04 04:26:34 UTC