Airworthiness Directive 2011-16571
one-timeAirworthiness Directives; Schweizer Aircraft Corporation (Schweizer) Model 269A, A-1, B, C, C-1, and TH-55 Series Helicopters
What this AD requires
We are superseding an existing emergency airworthiness directive (EAD) for the specified Schweizer model helicopters that was previously sent to all known U.S. owners and operators. That EAD currently requires removing each locknut and verifying sufficient drag torque and retorquing, or if the locknut does not have sufficient drag torque, replacing the locknut with an airworthy locknut. This AD retains the existing EAD requirements but also requires within a specified time, modifying the expandable bolts and installing a cotter pin. This AD is prompted by a locknut working loose from a bolt attaching the tailboom support strut at the aft cluster fitting because the locknut installed on the expandable bolt did not have the proper threads. We are issuing this AD to modify each expandable bolt to allow adding a cotter pin to prevent the strut and driveshaft separating from the helicopter and subsequent loss of control of the helicopter.
Which aircraft AD 2011-16571 applies to
Model 269A, A-1, B, C: S/N 1846 and larger. Model 269C-1: S/N 0156 and larger. TH-55 series helicopters apply only with Aft Cluster Fitting Modification Kit P/N SA-269K-106 installed. Unsafe condition: a locknut working loose on the tailboom aft cluster fitting strut because the locknut installed on one expandable bolt did not have the proper threads; AD contains terminating action requiring modification of each expandable bolt to allow installing a cotter pin, to prevent the strut and driveshaft separating from the helicopter and subsequent loss of control.
Whether AD 2011-16571 actually applies to your aircraft (by serial and installed parts) and whether it’s already complied with comes from that aircraft’s records.
How AD compliance is recorded
A valid compliance record (14 CFR 43.9) states:
Tailplate reads a tail number’s logbooks and matches every applicable AD — including this one — to its compliance evidence, with recurring next-due dates computed.
Look up a tail number →Read the full directive (Federal Register)Applicability is derived from the FAA directive corpus and is advisory, not a legal airworthiness determination. Compliance is established only from an aircraft’s actual records.