Summary
The FAA proposes to adopt a new airworthiness directive (AD) for all De Havilland Aircraft of Canada Limited Model DHC-8-401 and -402 airplanes. This proposed AD was prompted by reports of bleed air leaks in the wing box area and failure of the leak detection shroud. This proposed AD would require removing and inspecting the affected V-band coupling and check valve seals, doing corrective actions if necessary, and replacing the coupling and seals with a redesigned assembly. The FAA is proposing this AD to address the unsafe condition on these products.