Airworthiness Directive · Amendment 39-17273 · Turbomeca S.A. Turboshaft Engines
Turbomeca S.A. Turboshaft Engines
This AD applies to all Turbomeca S.A. Arriel 1A, 1A1, 1A2, 1B, 1C, 1C1, 1C2, 1D, 1D1, 1E2, 1K1, 1S, and 1S1 turboshaft engines that have not incorporated Turbomeca S.A. Modification TU360.
We are superseding an existing airworthiness directive (AD) for all Turbomeca S.A. Arriel 1A, 1A1, 1A2, 1B, 1C, 1C1, 1C2, 1D, 1D1, 1E, 1E2, 1K, 1K1, 1S, and 1S1 turboshaft engines. That AD currently requires initial and repetitive visual inspections for erosion caused by dust ingestion and, if necessary, cleaning of the gas generator (module M03). This new AD requires determining the engine history; performing a one-time visual inspection of the axial compressor for erosion; performing initial and repetitive cleaning of the gas generator hollow shaft; and replacing the rear bearing if the amount of dust collected during cleaning exceeds 8 grams. This AD also includes an optional terminating action. This AD was prompted by in-service experience which has shown that dust inside the gas generator hollow shaft may be found when the axial compressor wheel has less erosion than initially assessed. We are issuing this AD to prevent an unbalance of the gas generator rotating assembly, which may lead to gas generator rear bearing failure, and uncommanded engine shutdown.
(1) Within 50 engine hours after the effective date of this AD, determine the engine history and perform the maintenance actions at the specified schedules. Use paragraphs 1.A. and 2.A. through 2.C. of Turbomeca S.A. Alert Mandatory Service Bulletin (MSB) No. A292 72 0230, Version C, dated February 29, 2012 to perform the maintenance actions and to establish the cleaning schedule.
(2) If during any of the cleanings, the dust weight collected inside the gas generator hollow shaft is more than 8 grams, replace the gas generator rear bearing before further flight.
(3) After the effective date of this AD, if there are any changes in accordance with paragraph 1.A.(1)(a)1.3 of Turbomeca S.A. Alert MSB No. A292 72 0230, Version C, dated February 29, 2012, within 50 engine hours time-in-service after such a change, accomplish the actions as specified in paragraphs (e)(1) and (e)(2) of this AD.
(4) After the effective date of this AD, do not install any gas generator (module M03) on an engine unless it is in compliance with this AD.
(5) After the effective date of this AD, do not install any gas generator rear bearing that has operated on an engine with a hollow shaft that has been found to have a dust weight more than 8 grams.
As optional terminating action to the repetitive actions in this AD, modify the engine by incorporating Turbomeca S.A. Modification TU360.
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.
