Airworthiness Directive · Amendment 39-12771 · Sikorsky Model S-70A and S-70C Helicopters
Sikorsky Model S-70A and S-70C Helicopters
Model S-70A helicopters, serial numbers (S/N) 700029, 701129, 701322, 701325, 701327, 701329, 701331, 701333, 701592, 701593, 701594, 701595, 701613, 701614, 701825, 701835, 702127, and 702129, and Model S-70C helicopters, S/N 70583, 70785, 70788, 70792, 70793, 70794, 70797, 70798, 70799, 70800, 70811, 70812, 70813, 70830, 70831, 70836, 70837, 70848, 70855, 70856, 70867, 70868, 70879, 70884, 70892, 70910, 70918, 70927, 70928, 70929, 70949, 70950, 70951, 70954, 70957, 70958, 70959, 70965, 70966, and 701029, certificated in any category.
This amendment supersedes an existing airworthiness directive (AD) for Sikorsky Model S-70A and S-70C helicopters. That AD currently requires inspecting a certain part-numbered main landing gear drag beam (beam) for a crack, removing any cracked beam before further flight, and reducing the torque of the jackpad mounting bolt retention nut (nut) of each beam. This amendment contains the same actions but requires those actions for another beam part number (P/N). This amendment is prompted by the inadvertent omission in the current AD of the additional beam that is susceptible to failure due to stress corrosion resulting from sustained excessive tensile stress due to excessive torque of the nut. The actions specified by this AD are intended to prevent excessive torque of the nut, failure of a beam, and subsequent loss of control of the helicopter during takeoff or landing.
