Summary
We propose to adopt a new airworthiness directive (AD) for all Sierra Hotel Aero, Inc. (formally Navion Aircraft LLC) Models Navion (L-17A), Navion A (L-17B), (L-17C), Navion B, Navion D, Navion E, Navion F, Navion G, and Navion H airplanes. This proposed AD would require a one-time inspection of the entire fuel system and repetitive inspections of certain fuel selector valves. This proposed AD results from reports of airplane accidents associated with leaking or improperly operating fuel selector valves. We are proposing this AD to detect and correct fuel system leaks or improperly operating fuel selector valves, which could result in the disruption of fuel flow to the engine. This failure could lead to engine power loss.