Airworthiness Directive · Amendment 39-17440 · Turbomeca S.A. Turboshaft Engines
Turbomeca S.A. Turboshaft Engines
This AD applies to Turbomeca S.A. Arriel 1A1, 1A2, 1B, 1C, 1C1, 1C2, 1D, 1D1, 1E2, 1K1, 1S, and 1S1 turboshaft engines that have incorporated Modification TU 207 or TU 243, or have incorporated Turbomeca Service Bulletin (SB) No. 292 80 0168 or SB No. 292 80 0190.
We are adopting a new airworthiness directive (AD) for certain Turbomeca S.A. Arriel 1A1, 1A2, 1B, 1C, 1C1, 1C2, 1D, 1D1, 1E2, 1K1, 1S, and 1S1 turboshaft engines. This AD requires daily post-flight checks of the engine tachometer's unit cycle-counting feature. This AD also requires ground-run functional checks within every 1,000 operating hours. This AD was prompted by detailed analysis and review of the accuracy of the engine's tachometer cycle-counting feature. We are issuing this AD to prevent uncontained engine failure and damage to the helicopter.
(1) If a tachometer is installed on the engine, but is not used to count cycles, then no further action is required.
(2) During the post-flight maintenance inspection after the last flight of each day, verify that the cycles counted by the engine's tachometer unit agree with the cycles counted by the primary counting method.
(3) If the numbers are different, use the primary counting method thereafter to determine all cycle counts. Do not use the values from the tachometer cycle-counting feature.
(4) If the engine tachometer cycle-counting feature remains accurate, then every 1,000 operating hours, perform a ground-run functional check of the tachometer unit cycle-counting feature in addition to the daily inspections in paragraph (e)(2) of this AD. If the tachometer cycle-counting feature fails the check, thereafter, use only the primary cycle-counting method to count cycles.
(5) If the tachometer is replaced, follow the instructions in paragraphs (e)(2), (e)(3), and (e)(4) of this AD.
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.
