Opportunity
Federal Register #FAA20263488
FAA Proposed Airworthiness Directive for Main Rotor Shafts on Multiple Helicopter Models
Buyer
Federal Aviation Administration, Department of Transportation
Posted
April 21, 2026
Respond By
June 05, 2026
Identifier
FAA20263488
NAICS
336413
The Federal Aviation Administration (FAA), under the Department of Transportation, is proposing a new airworthiness directive (AD) that supersedes a previous directive for main rotor shafts (MRS) on various helicopter models. - Government Buyer: - Federal Aviation Administration (FAA), Department of Transportation - Aircraft Certification Service - OEMs and Vendors Mentioned: - Sikorsky Aircraft Corporation - Croman Corporation - Carson Helicopters - Glacier Helicopter - Robinson Air Crane - Siller Helicopters - Products/Services Requested: - Main rotor shafts (MRS) with part numbers: - S6135-20640-001 - S6135-20640-002 - S6137-23040-001 - Nondestructive inspection (NDI) for cracks on MRS - Replacement of MRS with cracks or those exceeding life limits - Removal of MRS with oversized dowel pin bores - Unique or Notable Requirements: - Recalculation of hours time-in-service (TIS) for all affected MRS - Lowering of retirement life limits for certain MRS (from 13,000 to 7,300 hours TIS for Non-REL MRS) - Establishment of retirement lives for repetitive external lift (REL) MRS - Mandatory removal of MRS with oversized dowel pin bores - Updates to type certificate holder names - Compliance actions required for 76 helicopters registered in the U.S. - Locations: - FAA Airworthiness Products Section, 10101 Hillwood Parkway, Fort Worth, TX 76177 - Sikorsky Aircraft Corporation, 124 Quarry Road, Trumbull, CT 06611
Description
The FAA proposes to supersede Airworthiness Directive (AD) 2015-20-12 affecting certain Sikorsky, Croman, Carson, Glacier, Robinson Air Crane, and Siller helicopter models. The directive requires recalculating hours time-in-service (TIS) of main rotor shafts (MRS), inspections for cracks, and replacement of parts exceeding life limits. The new proposal lowers retirement life limits for certain MRS, updates type certificate holder names, and mandates removal of MRS with oversized dowel pin bores to address unsafe conditions.