EASA SIB 2007-49: Eurocopter AS 332 and EC 225 helicopters - Tail Gearbox (TGB) Attachment Fittings Manufacturing Defect

What to do

Operators must inspect the TGB aft and forward attachment fittings within 50 flight hours to verify the presence of the blind hole. If missing, damaged bolts must be replaced, additional washers installed, and torque applied as specified. Full conformity of the fittings must be restored within 825 flight hours or by 2008-12-31, whichever occurs first. National aviation authorities should adopt the DGAC France Emergency Airworthiness Directive UF-2007-027 under their regulatory frameworks.

Summary

EASA Safety Information Notice No. 2007-49, issued on 2007-12-10, addresses a manufacturing defect in the tail gearbox (TGB) attachment fittings of Eurocopter AS332 C, C1, L, L1, L2 and EC225 LP helicopters with specific serial numbers. The defect involves interference caused by a missing blind hole in the structure fitting, affecting proper bolt tightening. This notice informs operators and maintenance organizations about the issue and references the DGAC France Emergency Airworthiness Directive UF-2007-027 for mandatory corrective actions.

What changed

This Safety Information Notice introduces awareness of a manufacturing anomaly in the TGB attachment fittings that can cause interference with the attachment bolts, potentially leading to damage and crack initiation. It mandates inspections and corrective measures including bolt replacement, installation of additional washers, and fitting replacement if non-conformities are found. The notice clarifies that the issue is due to manufacturing defects rather than design approval, thus falling outside EASA's direct AD authority but requiring national authority action.

Why it matters

The defect can compromise the structural integrity of the TGB attachment, risking loss of the tail gearbox and possible helicopter loss during critical flight phases such as takeoff and landing. Aviation professionals must ensure timely inspections and corrective actions to maintain airworthiness and safety. Compliance with the referenced Emergency Airworthiness Directive is essential to prevent potential catastrophic failures and ensure regulatory adherence.