Cockpit Additional Electrical Supply Always Operate

TASK 25-18-51-810-801-A
Cockpit Additional Electrical Supply Always Operate

1. Possible Causes

2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	1	VOLTMETER - TRUE RMS AC VOLTAGE MEASURING

B. Referenced Information

REFERENCE	DESIGNATION
ASM 251800
AMM 25-18-51-000-001	Removal of the Static Inverter

3. Fault Confirmation
Subtask 25-18-51-865-050-A ** ON A/C NOT FOR ALL

A. Make sure that this(these) circuit breaker(s) is(are) open, safetied and tagged:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
121VU	PILOTS OUTLETS/STAT INV	1NA	K25

Subtask 25-18-51-710-050-A ** ON A/C NOT FOR ALL

B. Test
(1) Disconnect all devices from captain outlet (5NA) and/or (4NA).
(2) Connect the VOLTMETER - TRUE RMS AC VOLTAGE MEASURING to the electrical test plug and make sure that there is no voltage 115VAC.

4. Fault Isolation
Subtask 25-18-51-865-051-A ** ON A/C NOT FOR ALL

A. Table of the circuit breakers used in this procedure:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
121VU	PILOTS OUTLETS/STAT INV	1NA	K25

Subtask 25-18-51-810-050-A ** ON A/C NOT FOR ALL

B. If there is confirmation of the fault:
(1) remove the static inverter (3NA) AMM 25-18-51-000-001.

Do a check of the voltage of the pin AE.

(a) If ground is present replace the Captain outlet (5NA) and/or First Officer (4NA).
(2) If the fault continues:

Connect on outlet 4NA and/or 5NA one equipement.

(a) Check there is no ground on pin AE.

If the ground is absent replace the oulets 4NA and 5NA.

(b) Check the wiring ASM 251800
1 If the wiring is not correct:

repair it.

(3) If the fault continues:

Check there is no ground on pin AE.

(a) If the is presence of ground replace the static inverter (3NA).

5. Close-up
Subtask 25-18-51-942-050-A ** ON A/C NOT FOR ALL

A. Put the aircraft back to its initial configuration.

[Rev.8 from Aug 2018] 2026.04.04 04:27:00 UTC