Removal of the Dual-Flapper Check Valve

TASK 47-20-43-000-001-A
Removal of the Dual-Flapper Check Valve

WARNING: PUT THE SAFETY DEVICES AND THE WARNING NOTICES IN POSITION BEFORE YOU START A TASK ON OR NEAR:

THE FLIGHT CONTROLS
THE FLIGHT CONTROL SURFACES
THE LANDING GEAR AND THE RELATED DOORS
COMPONENTS THAT MOVE.

MOVEMENT OF COMPONENTS CAN KILL OR CAUSE INJURY TO PERSONS AND/OR CAN CAUSE DAMAGE TO THE EQUIPMENT.

WARNING: DO NOT GO INTO THE WORK AREA UNTIL A MINIMUM OF 5 MINUTES AFTER YOU REMOVE THE ACCESS PANEL. LET AIR FLOW THROUGH THE WORK AREA. AIR FROM THIS SYSTEM HAS A LOW OXYGEN CONTENT AND CAN CAUSE INJURY OR DEATH.

WARNING: MAKE SURE THAT:

THERE ARE NO CAPS OR COVERS ON THE FUEL TANK VENTILATION DUCTS. CAPS OR COVERS WILL CAUSE OVERPRESSURE OR UNDERPRESSURE DAMAGE TO THE FUEL TANK.
NO PERSONS ARE NEAR THE FUEL TANK OR VENTILATION DUCTS OF THE FUEL TANK.

ZONE: 145
FIN: 4YM ** ON A/C NOT FOR ALL

1. Reason for the Job
Self explanatory
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	AR	PLUG - BLANKING
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER
No specific	1	SCRAPER - NON METALLIC

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
145	PRESS ZONE BETW WING CTR BOX MAIN GEAR
241EF

C. Referenced Information

REFERENCE	DESIGNATION
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)
TASK 53-32-12-000-002-A	Removal of the Cabin Floor Panels
Dual-Flapper Check Valve - Location and Detail

3. Job Set-up
Subtask 47-20-43-860-052-A ** ON A/C NOT FOR ALL

A. Aircraft Maintenance Configuration
(1) De-energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-862-002).

Subtask 47-20-43-865-052-A ** ON A/C NOT FOR ALL

B. Open, safety and tag this(these) circuit breaker(s):

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
121VU	IGGS/CTRL	7YA	N28
** ON A/C NOT FOR ALL
121VU	IGGS/CTRL	7YA	P28
** ON A/C NOT FOR ALL
122VU	CSAS / CTRL	1HW	U17

Subtask 47-20-43-010-051-A ** ON A/C NOT FOR ALL

C. Get Access
(1) Remove the cabin floor panel 241EF to get access to the top of the center tank (Ref. AMM TASK 53-32-12-000-002).

4. Procedure
Subtask 47-20-43-020-050-A ** ON A/C NOT FOR ALL

A. Removal of the Dual-Flapper Check Valve

WARNING: BEFORE YOU DO WORK IN OR NEAR A FUEL TANK, MAKE SURE THAT YOU OBEY ALL THE SAFETY PROCEDURES. THIS WILL PREVENT INJURY TO PERSONS AND/OR DAMAGE TO THE AIRCRAFT.

CAUTION: BE CAREFUL WHEN YOU TOUCH THIS ASSEMBLY. IT HAS PRECISION- TOLERANCE COMPONENTS WITH VERY POLISHED SURFACES. IF YOU ARE NOT CAREFUL, IT IS VERY EASY TO CAUSE DAMAGE TO THESE COMPONENTS (INTERNAL CONTAMINATION, EXTERNAL IMPACT DAMAGE).

CAUTION: DO NOT LET PAINT PARTICLES GO INTO THE FUEL TANK. REMOVE THE PARTICLES WITH A VACUUM CLEANER (IF YOU CANNOT USE A VACUUM CLEANER, USE AN AIR BLOWER).

(1) Use a SCRAPER - NON METALLIC to remove the sealant from the nuts (1) and washers (2), and the paint from the screws (7).
(2) Remove the screws (7), the washers (8) and disconnect the bonding leads (9) and (10) from the dual-flapper check valve (4).
(3) Disconnect the union (5) from the dual-flapper check valve (4).
(4) Put the PLUG-BLANKING in each disconnected line end.
(5) Remove the nuts (1) and the washers (2) from the dual-flapper check valve (4).
(6) Remove and discard the O-rings (3).
(7) Carefully remove the dual-flapper check valve (4).
(8) Remove and discard the O-rings (6) and (11).
(9) Put a blanking cover on the opening of the dual-flapper check valve (4).

[Rev.10 from 2021] 2026.04.02 06:26:18 UTC