AD FAA-2016-0733

We propose to adopt a new airworthiness directive (AD) for Robinson Helicopter Company (Robinson) Model R44, R44 II, and R66 helicopters. This proposed AD would require a visual inspection of the main rotor blade (MRB) and either removing or altering it. This proposed AD is prompted by a report that a fatigue crack was found at an MRB's trailing edge and a determination that some MRBs may have reduced blade thickness due to blending out corrosion. The proposed actions are intended to prevent an MRB fatigue crack, which could lead to MRB failure and subsequent loss of helicopter control.