Summary
This document proposes to adopt a new airworthiness directive (AD) that would apply to certain HOAC Austria Model DV-20 Katana airplanes. The proposed action would require replacing the muffler with one of improved design, installing a heat shield around the exhaust system endpipe, and adjusting the airplane weight and balance. Reports of cracks in the welding joint that connects the exhaust system endpipe to the muffler on three of the affected airplanes prompted the proposed action. The actions specified by the proposed AD are intended to prevent separation of the exhaust system endpipe from the muffler because of cracks in the welding that connects these parts, which could result in heat damage to the electrical system and engine controls.