FAA Issues Airworthiness Directive for Hélicoptères Guimbal Cabri G2 Over Weak ELT Signal Risk

The FAA has adopted a new airworthiness directive for certain Hélicoptères Guimbal (HG) Model Cabri G2 helicopters, published in the Federal Register on September 28, 2026 as FAA-2026-4630. The AD addresses a potential malfunction of the helicopter's emergency locator transmitter caused by improper antenna installation, and requires operators to revise the existing rotorcraft flight manual for affected helicopters.

The directive was prompted by findings that improper antenna placement inside the cockpit caused the ELT to produce weaker-than-expected signals on 121.5 MHz and 406 MHz frequencies. Both HG cockpit ELT antenna configurations are affected. The AD follows European Union Aviation Safety Agency AD 2025-0282, issued December 12, 2025, which first identified the unsafe condition. The FAA estimates 70 U.S.-registered helicopters are affected.

The RFM revision is required; once completed, overwater operations under 14 CFR Part 135 will be prohibited until an optional antenna modification is performed. That optional modification — relocating the ELT antenna from inside the cockpit to an exterior position per Guimbal Mandatory Service Bulletin SB 25-006 B, dated December 12, 2025 — is estimated to cost up to $1,298 per aircraft, comprising 3.5 work-hours at $85 per hour and up to $1,000 in parts.

One anonymous commenter requested that the antenna modification be made mandatory with a six-month compliance deadline, arguing the RFM revision only treats the symptom rather than the root cause. The FAA disagreed, noting that its regulations require an ELT only for Part 135 overwater operations, and that prohibiting such operations via the RFM revision effectively removes the regulatory context in which a fully functional ELT is mandated. No changes to the AD were made as a result of the comment. The AD takes effect with the Director of the Federal Register's approval of incorporated-by-reference material as of November 2, 2026.

This case belongs to a familiar regulatory pattern in rotorcraft safety: when a hardware fix is expensive relative to the fleet affected, a regulator can achieve compliance by narrowing where and how an aircraft may be flown rather than mandating the repair itself. Here, restricting overwater Part 135 operations removes the operational condition that requires a working ELT, which resolves the safety gap on paper without forcing operators to spend on the antenna relocation.

For Cabri G2 operators, the practical question becomes which mission profiles depend on overwater Part 135 work. An operator running only inland training or tour flights may see no operational effect from the RFM revision, while one running overwater charter work faces a real choice between grounding that segment of business or paying for the exterior antenna relocation.

What remains to be watched is uptake of the optional modification itself: whether operators who need overwater capability move quickly to the Guimbal service bulletin fix, and whether EASA or the FAA revisit the voluntary approach if compliance lags. The FAA's rejection of a mandatory deadline leaves that timeline entirely in operators' hands.