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Notice of proposed rulemaking (NPRM).

We propose to adopt a new airworthiness directive (AD) for MDHI Model 369A, 369D, 369E, 369FF, 369H, 369HE, 369HM, 369HS, 500N, and 600N helicopters. This proposed AD would require inspecting each main rotor blade (MRB) for a crack. This proposed AD is prompted by reports of cracked MRBs. The actions of this proposed AD are intended to address an unsafe condition on these helicopters.

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