FAA Mandates Helicopter Mast Inspections
Published Date: 6/9/2026
Rule
Summary
If you own or operate a Hélicoptères Guimbal Cabri G2 helicopter, listen up! The FAA found cracks on the main rotor mast after some shaky flights, so they’re requiring inspections, fixes, and upgrades to keep things safe. These rules kick in June 24, 2026, and could mean some repair costs, but safety first!
Analyzed Economic Effects
5 provisions identified: 0 benefits, 5 costs, 0 mixed.
Mandatory MR Mast Inspections Now Required
If you own or operate a Hélicoptères Guimbal Cabri G2 helicopter, you must inspect the main rotor (MR) mast for cracks and corrosion using 10X magnification within the AD compliance times. Compliance times vary by group: Group 1 may need inspection before further flight or within 3 months/150 hours (or before 2 years from original certificate), Group 2 within 3 months/150 hours or before exceeding 9 months/150 hours since last MGB work, and Group 3 within 3 months or within 150 hours; any new vibration must be inspected before further flight. The AD is effective June 24, 2026.
Potential High Repair/Overhaul Costs for MR Mast
If inspections reveal defects or cracks that remain after paint removal, the MR mast must be removed from service and repaired using an FAA-, EASA-, or DOA-approved method. The FAA notes manufacturer guidance that an MR mast repair (overhaul) may cost up to $19,950 per repair.
Required MR Mast Modification and Corrosion Protection
After inspection, you must modify each MR mast to apply corrosion protection in accordance with Guimbal Service Bulletin SB 18-023 E before further flight, unless already done. The FAA estimates modification labor at 2 work-hours (2 x $85 = $170) per helicopter and estimates this AD affects 67 U.S. helicopters.
Prohibition on Installing Certain MGB Parts
Starting on the effective date, you may not install any main gear box (MGB) with part number G21-10-000, G21-10-001, G21-10-002, or G21-10-003 unless the MR mast on that affected part has been modified per SB 18-023 E or HG MOD 18-038 and passed the required inspection before installation. This restriction applies from June 24, 2026.
14-Day Reporting Requirement for Defects
If any defects or cracks are found during inspection, you must report the inspection results to Hélicoptères Guimbal within 14 days after the inspection (or after the effective date, whichever is later). The Paperwork Reduction Act paperwork burden is estimated at about 1 hour per response (OMB Control Number 2120-0056).
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