Summary
We propose to adopt a new airworthiness directive (AD) for MD Helicopters Inc. (MDHI) Model 600N helicopters. This proposed AD would require establishing a life limit for the main rotor (M/R) blade upper control collective/longitudinal link assembly (link assembly). This proposed AD is prompted by the discovery that the life limit was omitted from the maintenance manual. The actions of this proposed AD are intended to prevent an unsafe condition on these products.