Summary
This document proposes to adopt a new airworthiness directive (AD) that would apply to Aerospace Technologies of Australia Pty Ltd. (ASTA) Models N22B, N22S, and N24A airplanes. The proposed action would require repetitively inspecting the stub wing upper front spar cap flanges for cracks, and repairing any cracked part. The proposed AD results from fatigue tests that show that the stub wing upper front spar cap flanges could fail over time because of fatigue. The actions specified by the proposed AD are intended to prevent structural failure of the front spar caused by cracks in the stub wing upper front spar cap flanges, which could result in loss of control of the airplane.