Airworthiness Directives; Bombardier Model DHC-7-100, -101, -102, and -103 Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to certain Bombardier Model DHC-7-100, -101, -102, and -103 series airplanes, that requires inspecting the endcaps of the main landing gear selector valve for leaks of hydraulic oil and, if leaks are detected, replacing the leaking endcaps or the entire selector valve. This amendment also requires eventual replacement or rework of certain selector valves, which would terminate the repetitive inspections. This amendment is prompted by a report of the collapse of the main landing gear due to an external leak of hydraulic oil in the landing gear selector valve, resulting from a fracture of the endcap. The actions specified by this AD are intended to prevent leaks of hydraulic oil from the main landing gear selector valve, which could result in the collapse of the main landing gear.