Airworthiness Directive 2015-25976
recurringAirworthiness Directives; Various Sikorsky-Manufactured Transport and Restricted Category Helicopters
What this AD requires
We are superseding Airworthiness Directive (AD) 98-26-02 for certain Sikorsky Aircraft Corporation (Sikorsky) Model S-61A, D, E, L, N, NM, R, and V helicopters. AD 98-26-02 required determining whether the main rotor shaft (MRS) was used in repetitive external lift (REL) operations, performing a nondestructive inspection (NDI) for cracks, replacing any unairworthy MRS, and establishing retirement lives for each REL MRS. This new AD retains some of the requirements of AD 98-26- 02 but determines a new retirement life for each MRS, expands the applicability to include additional helicopters, and requires removing from service any MRS with oversized dowel pin bores. This AD was prompted by the manufacturer's reevaluation of the retirement life for the MRS based on torque, ground-air-ground (GAG) cycle, and fatigue testing. We are issuing this AD to prevent MRS structural failure, loss of power to the main rotor, and subsequent loss of control of the helicopter.
Which aircraft AD 2015-25976 applies to
Applicability depends on the aircraft’s type certificate — check it against the specific tail.
Whether AD 2015-25976 actually applies to your aircraft (by serial and installed parts) and whether it’s already complied with comes from that aircraft’s records.
Supersession
Supersedes AD 98-26-02.
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.