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:
A DG-500MB experienced, after the engine shutdown, an uncommanded retraction of its powerplant. Investigations revealed that some bolts of the extension retraction mechanism had fractured because of fatigue stress due to increasing push-pull loads acting on incorrectly tightened screws. This condition, if not corrected, could lead to damage of the propeller and the fuselage, thereby reducing the structural integrity of the sailplane.
The proposed AD would require actions that are intended to address the unsafe condition described in the MCAI.