D.
Fuel Coupling Damage and Wear Limits Check
S 216-270
(1)
Before you install a coupling visually examine the tube ferrule(s), retaining ring(s) and nut(s) for these types of damage and wear limits:
(a)
Inspect the area for cracks.
1) Cracks are not permitted.
(b)
Inspect the contact areas for dents, nicks, scratches or cuts. 1) Dents, nicks, scratches or cuts are not permitted.
(c)
Inspect the retaining ring(s) to make sure the retaining ring(s) are not bent, twisted or out of round (deformed). 1) Deformed retaining rings are not permitted.
(d)
Inspect the tube ferrule(s) and nut(s) to make sure all of the contact surfaces are smooth. 1) Surface areas that are not smooth are not permitted.
(e)
Inspect the contact surface(s) that have an O-ring seal for wear. 1) Worn areas in the contact surfaces that have an O-ring seal
are not permitted.
2) FUEL COUPLINGS IN THE NACELLE STRUT AREA; The O-ring contact area minimum width is 0.20 inch (Fig. 601).
NOTE: The O-ring contact area is defined as the distance
____ between the two grooves worn into the fuel tube ferrule as shown in Figure 601 (View B-B and View D-D). The grooves are a result of contact with the retainer and or retaining ring(s).
(f) Inspect the tube ferrule and retaining ring for wear.
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(g) If the tube ferrule or retaining ring is worn, make sure the wear is within these permitted limits: 1) Ferrule diameter
a) Grooves worn into the ferrule as a result of contact with the retaining ring cannot have a groove depth of more than 0.010 inch.
2) Ferrule lip contact surfaces a) The ferrule lip contact surface cannot have a total decrease in the lip thickness of more than 0.010 inch. 3) Retaining ring inside or outside diameter a) The retaining ring inside or outside diameter can not have a total decrease in radial dimension of more than
0.020 inch.
(h) Visually examine the external surfaces of the nut(s) for indications of these types of damage and make sure the damage is permitted: 1) Do an inspection for cracks.
a) No cracks are permitted. 2) Do an inspection for scratches. a) The scratches in the couplings must not have a depth of more than 0.004 inch.
3) Do an inspection for nicks. a) The nicks in the couplings must have rounded bottoms. b) The nicks in the couplings must not have a depth of
more than 0.004 inch. c) You must remove all the burrs around the nick.
S 356-271
(2) Repair or replace all the couplings which have damage that is not permitted (AMM 28-22-07/801, AMM 28-22-07/401).
TASK 28-22-07-706-262
3. Engine Fuel-Feed Manifold Air Pressure Leak Check__________________________________________________
A. General
(1) This task does an air pressure leak check of engine fuel-feed manifold.
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747-400
MAINTENANCE MANUAL
B. Equipment
(1)
Air Pressure Source - 40 psig capacity
(2)
G28018 air pressure check equipment
(3)
Pressure Check Equipment - locally made test equipment (Fig. 601).
C.
References
(1)
AMM 28-11-00/201, Fuel Tanks
(2)
AMM 28-11-01/401, Center Wing Tank Access Door
(3)
AMM 28-11-02/401, Reserve and Main Tank Access Door
(4)
AMM 28-15-00/201, Fuel Scavenge System
(5)
AMM 28-22-07/401, Fuel Line for the Engine Fuel-Feed System
(6)
AMM 28-26-00/201, Defueling
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