Operators of Hughes369s and MD Helicopters MD500Ns must inspect main rotor blades before further flights, under an emergency airworthiness directive (AD) issued by the US Federal Aviation Administration.
The action follows the loss of a Hughes 369D caused by rotor blade failure due to fatigue cracking that originated at corrosion pits on the blade spar bonded surfaces.
The AD covers blades manufactured by Helicopter Technology, and requires operators to perform a one-time "tap" inspection of both the upper and lower surfaces of each blade for skin-to-spar bonding voids.
If any voids are detected that exceed inspection requirements, the blade must be replaced before further flight.
Source: Flight International
