AD FAA-2021-0339

The FAA proposes to adopt a new airworthiness directive (AD) for certain Airbus Canada Limited Partnership Model BD-500-1A10 and BD- 500-1A11 airplanes. This proposed AD was prompted by a design review that identified rib 0 of the center wing box (CWB) as an area where a single failure of a clamshell type refuel/defuel line coupling could lead to the accumulation of dangerous levels of electrostatic charges within the fuel tank. This proposed AD would require replacing the clamshell type refuel/defuel line coupling in the CWB at rib 0 with a threaded type fuel coupling, and installing an additional support bracket and clamp in the CWB at rib 0, as specified in a Transport Canada Civil Aviation (TCCA) AD, which is proposed for incorporation by reference. The FAA is proposing this AD to address the unsafe condition on these products.