Federal Register #2026-15978

FAA Mandates Inspections and Life Limit Reductions for Sikorsky Main Rotor Shafts on Multiple Helicopter Models

The Federal Aviation Administration (FAA), under the Department of Transportation, has issued a final rule updating airworthiness requirements for main rotor shafts (MRS) on multiple helicopter models. - Government Buyer: - Federal Aviation Administration (FAA), Aircraft Certification Service - OEMs and Vendors: - Sikorsky Aircraft Corporation (primary OEM for main rotor shafts) - Other affected certificate holders: Croman Corporation, Carson Helicopters, Glacier Helicopter, Robinson Air Crane, Siller Helicopters - Products/Services Requested: - Main Rotor Shafts (MRS) for various helicopter models - Part numbers: S613520640001, S613520640002, S613723040001 - No specific quantities provided; applies to all affected aircraft - Services required: - Nondestructive inspections (NDI) for cracks on MRS - Calculations to determine MRS usage in repetitive external lift (REL) or non-REL operations - Marking of REL MRS - Removal of MRS with oversized dowel pin bores - Record-keeping and compliance with revised retirement life limits - Unique/Notable Requirements: - Reduced retirement life for specified MRS part numbers (as low as 7,300 hours Time-In-Service for Non-REL MRS) - Mandatory compliance with Sikorsky Alert Service Bulletin No. 61B3569, Revision A - Applies to 76 U.S. helicopters across several models (S-61A, D, E, L, N, NM, R, V; SH-3H; S-61L; CH-3E; CH-3C; HH-3C; HH-3E; SH-3A, etc.) - Aimed at preventing structural failure and loss of control due to MRS issues

Description

The FAA is superseding Airworthiness Directive (AD) 2015-20-12 for certain helicopter models including Sikorsky Aircraft Corporation, Croman Corporation, Carson Helicopters, Glacier Helicopter, Robinson Air Crane, and Siller Helicopters. The AD requires inspections and calculations to determine the use of the main rotor shaft (MRS) in repetitive external lift (REL) operations, performing nondestructive inspections for cracks, marking REL MRS, establishing retirement lives, and removing MRS with oversized dowel pin bores. The new directive reduces the retirement life for certain MRS and updates the type certificate holder names. This action addresses an unsafe condition that could lead to structural failure and loss of control of the helicopter.

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