FAA echoes a Jan. 6 Boeing service bulletin (767-32A0225) today with a Special Airworthiness Information Bulletin that recommends inspections of Boeing 767-400ER aircraft -- specifically, the inner bore of the main landing gear truck beam.
The agency recommends that all owners and operators follow the Boeing instructions to reapply the fillet seal around the MLG forward tow fittings, inspect the aft drain passages for blockage, and clean of the MLG drain passage, if necessary. It notes that the service information also provides guidelines for inspecting the inside diameter of the MLG truck beam for corrosion and damage to the primer and applicable corrective actions.
The Boeing SB was prompted by a recent incident during taxi out that resulted in a fractured MLG truck beam. According to FAA, "preliminary data revealed corrosion damage in the inner diameter of the truck beam, and the aft drain hole was blocked and not draining properly."
The aircraft involved in this incident was nine years old and had accumulated 40,580 total flight hours and 6,062 total flight cycles when it happened, FAA says; inspections of other 767-400ER aircraft showed two more incidents of corrosion damage and pitting in the area where the other MLG truck beam fractured.