(2)
One Vent Scoop Closure Plug -F80080-88 or 9TE65-45412
(3)
One Surge Tank Drain Tube Plug Assembly -F80080-55
(4)
Two Drain Check Valve Plugs -F80080-112 or 10TE65-46517
(5)
One Float Valve Closure Plug -F80080-8
(6)
Two Tube Plug Assemblies -F80080-49
(7)
One Structural Vent Cover Assembly -F80080-56
N. Surge Tank Pressure Door Assembly -F80080-82 or F80080-5
O. Center Integral Wing Tank Pressure Test Door -F80172-7, F80172-1 or F80148-1
P. Water Safety Relief Manometer -F72951-1 (Fig. 105)
Q. Bypass Lock Assembly -ME65-16713
R. Wing Dry Bay Pressurization Test Equipment -F80258
3. Localizing External Fuel Leaks -Talcum Powder Method
A. General
(1)
Before defueling and entering any fuel tank which has a fuel leak, attempt to locate and isolate all fuel leaks in the affected tank. If leak is suspected of being in the upper part of the tank, above the normal full level, carefully overfill tank by manually depressing override button on the fueling shutoff valve. Override button should be released the instant fuel is detected at the surge tank sump drain valve.
CAUTION: LIMIT OVERFILLING TO ONE FUEL TANK AT A TIME AND DO NOT OVERFILL TANK IF TEMPERATURE EXTREMES ARE LIABLE TO BE ENCOUNTERED. EXPANSION SPACE FOR FUEL IN OVERFILLED TANK IS LIMITED TO VOLUME OF SURGE TANK AND ANY EXCESS FUEL WILL SPILL ON GROUND.
(2)
Every effort should be made to isolate and repair all fuel leaks regardless of classification (Ref par. 9., 28-11-0, Description and Operation) each time a tank is opened to repair a leak. If leak involves both the primary seal through the wing structure and the secondary seal through secondary barrier sealant coating, used on integral center wing section, the leak should be treated as two separate failures to be localized and repaired independently.
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B. Prepare for Leak Localization
(1)
Remove aerodynamic smoother if applied over affected seams or joints.
(2)
If center tank upper surface is to be checked on airplanes with integral center wing tank, remove seats, carpet, and floor panels in passenger cabin as required to expose center wing tank upper panel from front to rear spar and from left BBL 70.85 to right BBL 70.85.
(3)
If center tank lower surface is to be checked on airplanes with integral center wing tank, open air conditioning equipment bay doors. Remove air conditioning equipment as necessary to check center tank lower surface (Ref Chapter 21).
C. Localize Leak
(1)
Wipe leak area dry using absorbent cotton cloth. Blow out all wet seams and corners.
CAUTION: HOLD AIR HOSE . INCH MINIMUM FROM STRUCTURE TO PREVEMT DAMAGE TO SEALS THAT ARE NOT FAULTY.
(2)
Dust suspected area immediately with talcum powder using a soft bristle camel hair brush.
(3)
Observe dusted area carefully for signs of discoloration around fasteners or on surface of secondary barrier sealant coating if used.
(4)
Mark each leak point and repeat same procedure at successive locations until each external leak is localized.
(5)
Determine extent of leak path and pinpoint origin.
(a)
Study wing structure and decide possible paths of fuel from point of origin to point of detection.
(b)
If leak penetrates secondary barrier seal coating on integral center tank upper surface or outer face of center section front spar, failure of both primary and secondary seals is indicated. Strip secondary sealant coating as necessary to expose leak path through structure and pinpoint origin.
NOTE: Any structural buildup is a possible leak path and fuel may flow in structure outside tank boundaries.
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NOTE: Both secondary barrier sealant leak and leak through structure must be repaired independently.
(6) If leak point cannot be determined by the above methods, the internal pressure and bubble method should be used as a last resort (Ref par. 5).
4. Determining Nonsealant Leaks
A. General
(1) Fuel leaks in the main tanks will often be the result of improper installation of tubing components at tank boundaries. Leaks may also be found at electrical connections that pass through the front and rear spars. Fittings that are attached to ribs at tank ends are sealed with O-rings as are all other connections and fittings that pass through any tank boundary. Stiffeners, and rib end fittings at the front and rear spars, are sealed in part by fasteners that attach them to the wing skin and spars. These are all possible leak sources. Equipment and tube connection leaks at tank ends and along the spars will almost always be caused by a faulty O-ring or improper installation.
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