To Purge the Pressure Switch Feed Line of the Main Fuel Pumps

TASK 28-21-00-170-001-A
To Purge the Pressure Switch Feed Line of the Main Fuel Pumps

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.

CAUTION: BE CAREFUL WHEN YOU DO MAINTENANCE TASKS ON THE WING TRAILING EDGE:

DO NOT CAUSE DAMAGE TO THE ELECTRICAL CABLE RACEWAYS.
DO NOT CAUSE DAMAGE TO THE ELECTRICAL CABLE INSTALLATIONS.
MAKE SURE THAT THE ELECTRICAL CABLES ARE INSTALLED CORRECTLY. INCORRECT INSTALLATION CAN CAUSE DAMAGE.

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

REFERENCE	QTY	DESIGNATION
No specific	1	CONTAINER 5 L (1.32 USGAL)
No specific	1	HOSE - FUEL RESISTANT
No specific	1	SAFETY BARRIER(S)
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER
No specific	1	WARNING NOTICE(S)
98A28104030000	1	ADAPTER-BANJO

B. Referenced Information

REFERENCE	DESIGNATION
TASK 12-11-28-650-003-A	Pressure Refuel with Automatic Control
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)
TASK 28-00-00-910-001-A	Fuel Safety Procedures
TASK 28-21-15-000-003-A	Removal of the Fuel-Pump Pressure-Switch
TASK 28-21-15-400-001-A	Installation of the Fuel-Pump Pressure-Switch
TASK 28-25-00-869-001-A	Fuel Transfer
TASK 31-60-00-860-001-A	EIS Start Procedure
TASK 31-60-00-860-002-A	EIS Stop Procedure
Main Fuel Pump Pressure Switches - Location and Detail ** ON A/C NOT FOR ALL
Main Fuel Pump Pressure Switches - Location and Detail ** ON A/C NOT FOR ALL

3. Job Set-up
Subtask 28-21-00-941-083-A

A. Safety Precautions

WARNING: OBEY THE FUEL SAFETY PROCEDURES.

(1) You must obey the fuel safety procedures when you do work on the fuel system (Ref. AMM TASK 28-00-00-910-001).
(2) Put a WARNING NOTICE(S) in these positions:

in the cockpit, to tell persons not to operate the fuel system
in the cockpit, to tell persons not to operate the flight controls
on the refuel/defuel panel, to tell persons not to refuel the aircraft.

(3) Put the SAFETY BARRIER(S) in position.

Subtask 28-21-00-865-067-A

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
FOR FIN: 23QA (PRESS SWFUEL PUMP NO 1, L WING TK)
121VU	FUEL/L WING TK/PUMP1 SPLY	1QA	N23
123VU	L WING TK/PUMP 1/STBY SPLY	11QA	AD12
FOR FIN: 27QA (PRESS SWFUEL PUMP NO 2, L WING TK)
121VU	FUEL/L WING TK/PUMP2 SPLY	7QA	N26
FOR FIN: 24QA (PRESS SWFUEL PUMP NO 1, R WING TK)
121VU	FUEL/R WING TK/PUMP1 SPLY	2QA	Q23
123VU	R WING TK/PUMP 1/STBY SPLY	12QA	AE12
FOR FIN: 28QA (PRESS SWFUEL PUMP NO 2, R WING TK)
121VU	FUEL/R WING TK/PUMP2 SPLY	8QA	Q26
** ON A/C NOT FOR ALL
FOR FIN: 39QA (PRESS SWFUEL PUMP NO 1, CTR TK)
121VU	FUEL/CTR TK/PUMP1 SPLY	29QA	P23
FOR FIN: 40QA (PRESS SWFUEL PUMP NO 2, CTR TK)
121VU	FUEL/CTR TK/PUMP2 SPLY	30QA	P26

Subtask 28-21-00-480-051-A

C. Installation of Equipment

NOTE: Two persons are necessary to do this procedure:

one person in the cockpit to operate the switch for the applicable fuel pump
one person to purge the pressure switch feed line of the applicable fuel pump.

(1) Remove the applicable pressure switch (Ref. AMM TASK 28-21-15-000-003).
(2) Install the seal (5), the 98A28104030000 ADAPTER-BANJO (3), the seal (2) and the plug (1) on the valve assembly (6).
(3) Install a 9.65 mm (0.3799 in.) HOSE - FUEL RESISTANT (4) on the 98A28104030000 ADAPTER-BANJO (3). Put the other end of the hose into an empty CONTAINER 5 L (1.32 USGAL).

NOTE: When you tighten the plug (1) clockwise, the check valve on the valve assembly (6) will open. This will let fuel flow into the container if:

there is pressure in the presssure switch line
there is pressure from fuel left in the aircraft fuel tanks
the applicable fuel pump is set to ON.

Subtask 28-21-00-861-065-A

D. Aircraft Maintenance Configuration
(1) Energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-861-002).
(2) Start the Electronic Instrument System (Ref. AMM TASK 31-60-00-860-001).

4. Procedure
Subtask 28-21-00-170-050-B ** ON A/C NOT FOR ALL

WARNING: BE CAREFUL NOT TO GET AIRCRAFT FUEL IN YOUR MOUTH OR IN YOUR EYES. IF YOU GET FUEL ON YOUR SKIN OR ON YOUR CLOTHES, FLUSH IT IMMEDIATELY WITH WATER. IF NECESSARY, GET MEDICAL HELP. AIRCRAFT FUEL IS POISONOUS.

A. To Purge the Pressure Switch Feed Line of the Main Fuel Pumps

NOTE: Before you operate each pump, you must:

read the fuel contents of the center tank. Make sure that the center tank contains a minimum of 1000 kg (2204.6220 lb)
read the fuel contents of the wing inner tanks. Make sure that each wing inner tank contains a minimum of 1000 kg (2204.6220 lb)
close the applicable CTRL and SPLY CB(s). Make sure that the CB is open again before you remove the plug (1) and 98A28104030000 ADAPTER-BANJO (3) (refer to paragraph 3. B.).

(1) Make sure that there is sufficient fuel in the center tanks and wing inner tanks. Refuel or transfer fuel if applicable (Ref. AMM TASK 12-11-28-650-003) (Ref. AMM TASK 28-25-00-869-001).
(2) Close the applicable CBs for the applicable pressure switch (refer to paragraph 3. B.).

NOTE: The fuel can drain very quickly. Make sure that the hose (4) is held tightly in the container when the fuel pump(s) are ON.

(3) On panel 40VU set the P/BSW(s) to ON for the applicable fuel pump(s). Do not let more than 2 l (0.5283 USgal) of fuel into the container. Monitor the fuel to make sure that it is clear in color and free from unwanted material.
(4) Set the applicable fuel pump(s) to OFF.

Subtask 28-21-00-170-050-C ** ON A/C NOT FOR ALL

A. To Purge the Pressure Switch Feed Line of the Main Fuel Pumps

NOTE: Before you operate each pump, you must:

read the fuel contents of the wing tanks. Make sure that each wing tank contains a minimum of 1000 kg (2204.6220 lb)
close the applicable CTRL and SPLY CB(s). Make sure that the CB is open again before you remove the plug (1) and 98A28104030000 ADAPTER-BANJO (3) (refer to paragraph 3. B.).

(1) Make sure that there is sufficient fuel in the wing tanks. Refuel or transfer fuel if applicable (Ref. AMM TASK 12-11-28-650-003) (Ref. AMM TASK 28-25-00-869-001).
(2) Close the applicable CBs for the applicable pressure switch (refer to paragraph 3. B.).

NOTE: The fuel can drain very quickly. Make sure that the hose (4) is held tightly in the container when the fuel pump(s) are ON.

Subtask 28-21-00-080-051-A

B. Removal of Equipment
(1) Turn the plug (1) counter-clockwise to close the check valve on the valve assembly (6).
(2) Make sure that the fuel has drained fully and remove the hose (4).
(3) Remove the plug (1), the seals (2) and (5) and the 98A28104030000 ADAPTER-BANJO (3).
(4) Open the applicable CBs for the applicable pressure switch (refer to paragraph 3. B.).

5. Close-up
Subtask 28-21-00-420-050-A

A. Installation of Pressure Switches
(1) Install the applicable pressure switch (Ref. AMM TASK 28-21-15-400-001).

Subtask 28-21-00-865-069-A

B. Remove the safety clip(s) and the tag(s) and close this(these) circuit breaker(s):

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
FOR FIN: 23QA (PRESS SWFUEL PUMP NO 1, L WING TK)
121VU	FUEL/L WING TK/PUMP1 SPLY	1QA	N23
123VU	L WING TK/PUMP 1/STBY SPLY	11QA	AD12
FOR FIN: 27QA (PRESS SWFUEL PUMP NO 2, L WING TK)
121VU	FUEL/L WING TK/PUMP2 SPLY	7QA	N26
FOR FIN: 24QA (PRESS SWFUEL PUMP NO 1, R WING TK)
121VU	FUEL/R WING TK/PUMP1 SPLY	2QA	Q23
123VU	R WING TK/PUMP 1/STBY SPLY	12QA	AE12
FOR FIN: 28QA (PRESS SWFUEL PUMP NO 2, R WING TK)
121VU	FUEL/R WING TK/PUMP2 SPLY	8QA	Q26
** ON A/C NOT FOR ALL
FOR FIN: 39QA (PRESS SWFUEL PUMP NO 1, CTR TK)
121VU	FUEL/CTR TK/PUMP1 SPLY	29QA	P23
FOR FIN: 40QA (PRESS SWFUEL PUMP NO 2, CTR TK)
121VU	FUEL/CTR TK/PUMP2 SPLY	30QA	P26

Subtask 28-21-00-862-066-A

C. Aircraft Maintenance Configuration
(1) Stop the Electronic Instrument System (Ref. AMM TASK 31-60-00-860-002).
(2) De-energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-862-002).

Subtask 28-21-00-942-089-A

D. Removal of Equipment
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Remove the SAFETY BARRIERS.
(3) Discard the drained fuel in accordance with local procedures and rules.
(4) Remove the ground support and maintenance equipment, the special and standard tools and all other items.

[Rev.10 from 2021] 2026.04.02 06:17:21 UTC