Message Name:

FUEL LEAKAGE FROM REFUEL/DEFUEL LINE FITTING

Several operators have reported discovering fuel dripping from the witness drain in the forward wing-to-fuse fairing during pressure refueling. In each case, the source of the leak was traced to damaged o-rings in the coupling that connects the refuel/defuel tube either at the manifold side, or the opposite end where it connects to the refuel/defuel adapter.

• Investigation into these events found that during refueling when pressurized fuel enters, the tube can shift slightly causing a small angular deflection in the couplings. This movement of the tube each time the aircraft is refueled might over time cause the o-rings in the fitting to roll or become pinched, leading to a spiral failure of the o-ring and subsequent leakage.

• Refuel/Defuel Adapter
• O-ring
• Coupling

Advisory Wire/Service Bulletin: None

Full Throttle Blog/Forum Articles/Infoservice/Newsletter: None

Flight Operation Notifications Manual (FONM): None

1. If this occurs and the fittings need to be disassembled to replace the o-rings, accomplishing this task through the small access panel in the wing-to-fuse fairing can be a challenging task for anyone who is not a contortionist. One operator discovered and passed along to us an easy way to simplify the task. Rather then disassembling the shroud and coupling in place on the aircraft, remove the entire assembly together with the refuel and manifold adapters and replace the o-rings on a bench. To remove the unit as an assembly, simply disconnect the 2 drain tubes from the shrouds, remove the 3 screws from the manifold adapter and the 4 bolts, nuts, and washers from the refueling adapter. Once this is done the whole assembly can be pulled out from the wing root at the refuel adapter.
2. Maintenance personnel should also be aware that there is a small hole for pressure and thermal relief inside the refuel/defuel manifold to allow any residual pressure inside the tube to bleed into the right wing tank. Because of this, anytime the manifold adapter or either refuel/defuel valve is removed, expect a small amount of leakage to continue if the aircraft was not defueled.