Airworthiness Directive · Amendment 39-12826 · Turbomeca S.A. Arriel Models 1A, 1A1, 1B, 1D, and 1D1 Turboshaft Engines
Turbomeca S.A. Arriel Models 1A, 1A1, 1B, 1D, and 1D1 Turboshaft Engines
This airworthiness directive (AD) is applicable to Turbomeca S.A. Arriel models 1A, 1A1, 1B, 1D, and 1D1 turboshaft engines. These engines are installed on, but not limited to, Astar AS350D; Eurocopter AS350B, BA, B1, L1, and B2N; and Fennic AS550U2 helicopters.
This amendment adopts a new airworthiness directive (AD) that is applicable to Turbomeca S.A. Arriel models 1A, 1A1, 1B, 1D, and 1D1 turboshaft engines. This action requires installation of containment shield rings around the free turbine blade area, and installation of a double support around the gearbox free turbine bearing housing. This amendment is prompted by two reports of the cantilevered axis of the free turbine moving from its design position and inducing blade trajectories outside the current design free turbine containment area. This condition can lead to uncontainment of the free turbine during an overspeed event. The actions specified in this AD are intended to prevent uncontainment of the free turbine during an overspeed event, resulting in damage to the helicopter.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
