Sikorsky S-76 operators are inspecting main rotors following the discovery of cracks in blade skins. The US Federal Aviation Administration issued an emergency airworthiness directive (AD) on 26 May after three reports of 1.2-1.8m (4-6ft) sections of blades separating in flight and discovery of a 500mm crack in a blade.
Sikorsky has determined the cracks are the result of the incorrect manufacture of the metal skins by a supplier. Just over 200 blades are affected, involving 70 to 80 of the more than 500 S-76s in service.
The FAA is concerned the separated sections could hit a main or tail rotor blade and cause loss of control. The AD requires operators to visually inspect the upper and lower skins of affected blades immediately and every 3h service use. Sikorsky has developed a repair to end the AD.
Source: Flight International
