An airworthiness directive issued by the FAA on Thursday warns of tightening torque loss on the main-rotor-hub (MRH) to main-rotor-mast attachment bolts on Eurocopter AS 365 and SA 365 helicopters, which could lead to an in-flight loss of the main rotor head. The AD, which affects 36 U.S.-registered AS 365N/N1/N2/N3 and SA 365C/C1/C2 helicopters, becomes effective March 6, but the FAA is accepting comments on AD 2008-04-03 until April 21.
According to the FAA, the directive was issued following several reports of tightening torque loss on the MRH to main-rotor-mast bolt attachment. These conditions were found on Eurocopter-assembled attachments with fewer than 300 hours. The FAA estimates it will take about four hours to perform the tightening torque inspections, costing operators about $320 per aircraft. No parts are needed to comply with the directive.