Airworthiness Directives; McDonnell Douglas Helicopter Systems Model 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, 600N, and OH-6A Helicopters

This amendment supersedes an existing priority letter Airworthiness Directive (AD) 98-03-15, applicable to McDonnell Douglas Helicopter Systems (MDHS) Model 369, 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, 600N, and OH-6 helicopters that currently requires an inspection for main rotor blade (blade) cracks and for missing or cracked adhesive or paint. This amendment requires the same inspections required by the existing priority letter AD but deletes the Model 369 (Army YOH-6A), specifies recording torque events (TE), and establishes a shorter retirement life for certain blades. This amendment is prompted by an accident in which a blade failed on a Model 369D helicopter due to fatigue cracks. The actions specified by this AD are intended to detect cracks that could lead to failure of the blade and subsequent loss of control of the helicopter.