Summary
We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:
The in-flight loss of a propeller and pulley wheel from the engine of a Grob G 103 C Twin III SL powered sailplane has been reported.
Grob Aircraft AG suspects that the possible reasons for this loss can be due to an incorrect propeller track (the play at the propeller tip) and/or to a damaged propeller nut securing plate.
Those conditions, if not corrected, could also result in loosening of parts and, consequently could result in damage to the sailplane and possible injury to persons on the ground.
The proposed AD would require actions that are intended to address the unsafe condition described in the MCAI.