Airworthiness Directive · Amendment 39-14103 · Turbomeca S.A. Arrius 1A Turboshaft Engines
Turbomeca S.A. Arrius 1A Turboshaft Engines
This AD applies to Turbomeca S.A. Arrius 1A turboshaft engines. These engines are installed on, but not limited to, Eurocopter AS355N Twinstar helicopters.
The FAA is adopting a new airworthiness directive (AD) for Turbomeca S.A. Arrius 1A turboshaft engines. This AD requires initial and repetitive testing of the Free Turbine Overspeed Protection System. This AD results from an investigation into the Digital Electronic Control Unit (DECU) that revealed a malfunction of the Free Turbine Overspeed Protection System. This malfunction can exist despite the DECU passing all functional tests specified in the Engine Maintenance Manual. We are issuing this AD to prevent uncontained engine failure if a free turbine overspeed occurs.
You are responsible for having the actions required by this AD performed within the compliance times specified unless the actions have already been done.
Within 25 flight hours after the effective date of this AD, test the DECU Free Turbine Overspeed Protection System, using paragraph 2.B. of the Instructions to be Incorporated of Turbomeca Alert Mandatory Service Bulletin No. A319 77 0804, dated March 24, 2005.
(g) If the DECU Free Turbine Overspeed Protection System fails the test specified in paragraph (f) of this AD, replace the DECU before further flight.
Repeat the testing specified in paragraph (f) of this AD at each functional test of the DECU Free Turbine Overspeed Protection System. Information on the functional tests of the DECU Free Turbine Overspeed Protection System can be found in the Engine Maintenance Manual, Section 77-30-01. Recommended intervals for the functional test of the Turbine Overspeed Protection System can be found in the Engine Maintenance Manual, Section 05-10-02.
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.
Engines
