Airworthiness Directives; Various Restricted Category Helicopters

We propose to adopt a new airworthiness directive (AD) for various restricted category helicopters. This proposed AD would require cleaning and visually inspecting certain main rotor (M/R) blades and, depending on the outcome of the inspections, repairing or replacing the M/R blades. This proposed AD is prompted by a report of an M/R blade with multiple fatigue cracks around the blade retention bolt hole. The proposed actions are intended to detect a crack in the M/R blade, and prevent failure of the M/R blade and subsequent loss of helicopter control.