Airworthiness Directives; Robert E. Rust Models DeHavilland DH.C1 Chipmunk 21, 22, and 22A Airplanes

This amendment adopts a new airworthiness directive (AD) that applies to certain Robert E. Rust (R.E. Rust) Models DeHavilland DH.C1 Chipmunk 21, 22, and 22A airplanes. This AD requires you to repetitively inspect the tailplane attachment brackets and replace each bracket at a specified time. This AD also requires you to repetitively inspect each joint of the port and starboard engine mount frame and the rear upper mount frame tubes for cracks and/or damage and repair any cracks and/or damage found. This AD is the result of reports of stress corrosion cracking found on the tailplane attachment brackets and fatigue cracking and chaffing of the engine mount frame. The actions specified by this AD are intended to prevent failure of the tailplane attachment brackets caused by stress corrosion cracking and failure of the engine mount, which could result in loss of the tail section and separation of the engine from the airplane respectively. Such failures could lead to loss of control of the airplane.