FAA Orders Earlier Checks on Helicopter Rotor Shafts
Published Date: 4/21/2026
Proposed Rule
Summary
If you fly certain Sikorsky, Croman, Carson, Glacier, Robinson, or Siller helicopters, the FAA wants you to check and possibly replace parts of the main rotor shaft sooner than before. They’re lowering the allowed flying hours for some parts to keep everyone safer. Comments on these changes are open until June 5, 2026, and following the new rules might cost some time and money but will keep your helicopter flying strong.
Analyzed Economic Effects
4 provisions identified: 1 benefits, 3 costs, 0 mixed.
Main Rotor Shaft Life Reduced
If you operate one of the listed helicopters with a main rotor shaft (MRS) part number S6135-20640-001, S6135-20640-002, or S6137-23040-001, the FAA would reduce the retirement life for Non-REL MRS from 13,000 hours TIS to 7,300 hours TIS. If a Non-REL MRS has 7,300 hours TIS or more and is installed, you must remove it at the next main gearbox overhaul; if it is uninstalled or in overhaul you must remove it before further flight. You must record the new retirement life on the MRS component history card within 5 days after the effective date of the AD.
FAA Cost Estimate: 76 Helicopters Affected
The FAA estimates the proposed AD would affect 76 helicopters on the U.S. registry. Estimated per-helicopter costs are: NDI of an REL MRS — $305 (3 work-hours at $85/hr plus $50 parts); replace/remove an MRS — $81,471 (3 work-hours at $85/hr plus $81,216 parts); revise a log card — $85 (1 work-hour). The FAA's total estimated operator costs are $23,180 for NDI, $6,191,796 for replacements/removals, and $6,460 for log card revisions.
Mandatory Crack Inspection and Marking
If you operate the affected helicopters, you must perform a nondestructive inspection (NDI) for cracks on each MRS within 1,100 hours TIS after November 24, 2015; any cracked MRS must be replaced before further flight. If an MRS is determined to be a repetitive external lift (REL) MRS, you must etch "REL" on the shaft near the part serial number and record lift cycles and hours TIS (including daily lift-cycle recording).
Remove Shafts With Oversized Dowel Bores
If an MRS has an oversized dowel pin bore (0.8860 inches or greater), you must remove that MRS from service within 50 hours TIS after November 24, 2015. The AD requires removing any MRS with oversize dowel pin bores to address the unsafe condition.
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Key Dates
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