EASA AD US-2021-05-19
Tail Rotor Control System - Arm Assembly - Life Limit
Summary
The FAA Airworthiness Directive 2021-05-19 addresses Sikorsky Aircraft Model S-61L, S-61N, S-61NM, S-61R helicopters and Sikorsky Aircraft Corporation Model S-61A, S-61D, S-61E, and S-61V restricted category helicopters equipped with arm assembly part number S6140-62614-009. This directive establishes a life limit for the tail rotor control system arm assembly to prevent operation beyond 15,000 hours time-in-service (TIS).
What Changed
This new airworthiness directive requires operators to review the mixer unit component log card or equivalent record to verify the arm assembly's life limit entry and calculate the remaining life. If the arm assembly has reached or exceeded 15,000 hours TIS, it must be removed from service. The AD expands applicability beyond previous service bulletins to include additional Sikorsky S-61 models and restricted category helicopters.
Why It Matters
This AD is critical for aviation professionals because exceeding the arm assembly's life limit could lead to reduced or loss of tail rotor control, compromising helicopter safety. Operators and maintenance organizations must ensure compliance to prevent potential accidents and maintain airworthiness. Accurate record-keeping and timely replacement of the arm assembly are essential to meet regulatory requirements and ensure safe flight operations.
What To Do
Affected operators must review the mixer unit component log card or equivalent record within 90 days of the AD's effective date to confirm the arm assembly's life limit entry. If missing, they must add the entry and calculate remaining life per Sikorsky's service bulletin. Arm assemblies with 15,000 or more hours TIS, or those with unknown hours, must be removed from service before further flight.
Your fleet's weekly compliance brief
AI-summarized regulatory changes, compliance deadlines, and action items — filtered to your aircraft, every Monday.
AI-generated summary from official EASA source document. Always verify against the original.