Built-In Test Equipment (BITE) Test of the Master Control Unit (MCU)

TASK 25-21-00-740-001-A
Built-In Test Equipment (BITE) Test of the Master Control Unit (MCU)

ZONE: 200
FIN: 55HP1 ** ON A/C NOT FOR ALL
FIN: 55HP2 ** ON A/C NOT FOR ALL

1. Reason for the Job
Self explanatory
2. Job Set-up Information
A. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
200	UPPER HALF FUSELAGE

B. Referenced Information

REFERENCE	DESIGNATION
TASK 24-41-00-861-002-A	Energize the Aircraft Electrical Circuits from the External Power
TASK 24-41-00-861-002-A-01	Energize the Aircraft Electrical Circuits from the APU
TASK 24-41-00-861-002-A-02	Energize the Aircraft Electrical Circuits from Engine 1(2)
TASK 24-41-00-862-002-A	De-energize the Aircraft Electrical Circuits Supplied from the External Power
TASK 24-41-00-862-002-A-01	De-energize the Aircraft Electrical Circuits Supplied from the APU
TASK 24-41-00-862-002-A-02	De-energize the Aircraft Electrical Circuits Supplied from the Engine 1(2)
Master Control Unit (MCU) ** ON A/C NOT FOR ALL
Master Control Unit (MCU) ** ON A/C NOT FOR ALL
Master Control Unit (MCU) ** ON A/C NOT FOR ALL
Master Control Unit (MCU) ** ON A/C NOT FOR ALL
Master Control Unit (MCU) ** ON A/C NOT FOR ALL

3. Job Set-up
Subtask 25-21-00-861-055-A ** ON A/C NOT FOR ALL

A. Energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-861-002).

Subtask 25-21-00-010-053-A ** ON A/C NOT FOR ALL

B. Get Access
(1) Open the door of the related overhead stowage compartment.
(2) Remove the cover.

Subtask 25-21-00-865-057-A ** ON A/C NOT FOR ALL

C. Make sure that this(these) circuit breaker(s) is(are) closed:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
2000VU	INSEAT POWER-MCU 2	59HP	B08
2000VU	INSEAT POWER-MCU 1	58HP	B05
** ON A/C NOT FOR ALL
2000VU	SEAT POWER-MCU 2	59HP	B08
2000VU	SEAT POWER-MCU 1	58HP	B05

4. Procedure
Subtask 25-21-00-740-050-B ** ON A/C NOT FOR ALL

A. BITE Test of the MCU

Master Control Unit (MCU) ** ON A/C NOT FOR ALL

(1) On the MCU, make sure that these indicators are on (green):

The BITE indicator
The three input power indicators
The five Ground Fault Interruption (GFI) indicators
The five output power indicators.

(2) Do this test procedure:

ACTION	RESULT
1.On the MCU: Push the LRU RESET pushbutton switch.	On the MCU: The BITE indicator comes on (amber). The five GFI indicators momentarily come on (amber) and then go off. The five output power indicators go off.
2.After approximately 50 seconds:	On the MCU: All indicators are on (green).

Subtask 25-21-00-740-050-C ** ON A/C NOT FOR ALL

A. BITE Test of the Master Control Unit

Master Control Unit (MCU) ** ON A/C NOT FOR ALL

(1) On the MCU, make sure that all indicators are on:

The five port-bite-indicators are green
The five port-power-state indicators are yellow
The one general-bite indicator is green
The one input power-state indicator is yellow.

(2) Do this test procedure:

ACTION	RESULT
1.Do a reset of the related MCU.	The MCU does a "POWER ON" lamp test. NOTE: During power up all indicators come on and go off two times. After the activation of the MCU-outputs all indicators come on and stay on.
2.After five seconds or less:	On the MCU: The five port-bite-indicators are green The five port-power-state indicators are yellow The one general-bite indicator is green The one input power-state indicator is yellow.

5. Close-up
Subtask 25-21-00-410-050-A ** ON A/C NOT FOR ALL

A. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Install the cover.
(3) Close the door of the related overhead stowage compartment.
(4) Remove the ground support and maintenance equipment, the special and standard tools and all other items.

Subtask 25-21-00-862-055-A ** ON A/C NOT FOR ALL

B. De-energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-862-002).

[Rev.10 from 2021] 2026.03.31 23:30:17 UTC