Summary
This document proposes to adopt a new airworthiness directive (AD) that would apply to certain Robert E. Rust (R.E. Rust) Models DeHavilland DH.C1 Chipmunk 21, 22, and 22A airplanes. This proposed AD would require you to inspect the fuselage to determine if a steel fuselage center-section tie bar fitted with bushings in the end lug bolt holes is installed. If this bushed steel fuselage center-section tie bar is installed, this proposed AD would decrease the safe life limit. This proposed AD is the result of reports that certain replacement steel fuselage center-section tie bars installed on the affected airplanes could fail before the originally published safe life limit. The actions specified by this proposed AD are intended to prevent early failure of these bushed steel fuselage center-section tie bars, which could result in reduced structural integrity of the wings. Such a condition could lead to loss of control of the airplane.