Summary
We propose to adopt a new airworthiness directive (AD) for certain serial number Lycoming Engines reciprocating engines. This proposed AD was prompted by events of propeller governor shaft set screws coming loose due to improper installation, which could result in engine oil loss, damage to the engine, and damage to the airplane. This proposed AD would require application of Loctite 290, or equivalent, to the threads of the propeller governor shaft set screw at each installation of the set screw in addition to the peening of crankcase hole threads. We are proposing this AD to prevent the propeller governor shaft set screw from coming loose, causing damage to the engine, and damage to the airplane.