AD 2010-10-09 Airworthiness Directives; Turbomeca Arriel 1B, 1D, 1D1, and 1S1 Turboshaft Engines

This AD applies to Turbomeca Arriel 1B (that incorporate Turbomeca Modification (mod) TU 148), Arriel 1D, 1D1, and 1S1 engines that do not incorporate mod TU 347. Arriel 1B engines are installed on, but not limited to, Eurocopter AS-350B and AS-350BA “Ecureuil” helicopters. Arriel 1D engines are installed on, but not limited to, Eurocopter France AS-350B1 “Ecureuil” helicopters. Arriel 1D1 engines are installed on, but not limited to, Eurocopter France AS-350B2 “Ecureuil” helicopters. Arriel 1S1 engines are installed on, but not limited to, Sikorsky Aircraft Corporation S-76C helicopters.

You are responsible for having the actions required by this AD performed within the compliance times specified unless the actions have already been done. Initial Relative Position Check of 2nd Stage Turbine Blades (f) Do an initial relative position check of the 2nd stage turbine blades using the Turbomeca Mandatory Service Bulletins (MSBs) specified in the following Table 1. Do the check before reaching any of the intervals specified in Table 1 or within 50 hours time-in-service after the effective date of this AD, whichever occurs later. Table 1—Initial and Repetitive Relative Position Check Intervals of 2nd Stage Turbine Blade Turbomeca engine model Initial relative position check interval Repetitive interval Mandatory Service Bulletin Arriel 1B (that incorporate mod TU 148), 1D1, and 1D Within 1,200 hours time-since-new (TSN) or time-since-overhaul (TSO) or 3,500 cycles-since-new (CSN) or cycles-since-overhaul (CSO), whichever occurs earlier Within 150 hours time-in-service-since-last-relative-position-check (TSLRPC) A292 72 0807, Version E, dated October 29, 2009, paragraphs 2B(1)(a) and (b), or 2B(2)(a). Arriel 1S1 Within 1,200 hours TSN or TSO or 3,500 CSN or CSO, whichever occurs earlier Within 150 hours TSLRPC A292 72 0810, Version C, dated July 24, 2009, paragraphs 2B(1)(a) and (b), or 2B(2)(a), (b), and (c). Repetitive Relative Position Check of 2nd Stage Turbine Blades (g) Recheck the relative position of 2nd stage turbine blades at the TSLRPC intervals specified in Table 1 of this AD, using the Turbomeca MSBs indicated. Credit for Previous Relative Position Checks (h) Credit is allowed for previous relative position checks of 2nd stage turbine blades done using the following Turbomeca MSBs: (1) MSB No. A292 72 0263, Update Nos. 1 through 5. (2) MSB No. A292 72 0807, Original, and Update No. 1 through Version D. (3) MSB No. A292 72 0809, Update No. 1. (4) MSB No. A292 72 0810, Original, and Version A through Version B. Initial Replacement of 2nd Stage Turbines on Arriel 1B Engines (i) Initially replace the Arriel 1B 2nd stage turbine disk and blades with an inspected 2nd stage turbine that does not incorporate mod TU 347 and is fitted with new blades or with a 2nd stage turbine that incorporates mod TU 347, using Turbomeca MSB No. A292 72 0807, Version E, dated October 29, 2009, paragraphs 2B(1)(c) or (d), or 2B(2)(b) or (c), at the following times: (1) Replace before further flight on engines with a 2nd stage turbine disk having accumulated more than 2,200 hours TIS since-new or since-last-inspection, whichever occurs later, or with 2nd stage turbine blades that have accumulated more than 3,000 hours TIS since-new. (2) For engines with 2nd stage turbine blades having accumulated on the effective date of this AD, more than 1,800 hours TIS since-new, but 3,000 or fewer hours TIS since-new, replace before reaching any of the following: (i) 400 hours TIS from the effective date of this AD, or (ii) 3,000 hours TIS since-new on the 2nd stage turbine blades, or (iii) 2,200 hours TIS since-new or since-last-inspection, whichever occurs later, on the 2nd stage turbine disk. (3) For engines with 2nd stage turbine blades having accumulated on the effective date of this AD, more than 900 hours TIS since-new, but 1,800 or fewer hours TIS since-new, replace before reaching any of the following: (i) 800 hours TIS from the effective date of this AD, or (ii) 2,200 hours TIS since-new or since-last-inspection, whichever occurs later, on the 2nd stage turbine disk. (4) For engines with 2nd stage turbine blades having accumulated on the effective date of this AD, 900 or fewer hours TIS since-new, replace before the 2nd stage turbine blades have accumulated 1,200 hours TIS since-new. Repetitive Replacements of 2nd Stage Turbines on Arriel 1B Engines (j) Thereafter, for 2nd stage turbines that do not incorporate mod TU 347, replace the 2nd stage turbine disk and blades before the blades have accumulated 1,200 hours TIS since-new. Initial Replacement of 2nd Stage Turbines on Arriel 1D and 1D1 Engines (k) Initially replace the Arriel 1D and 1D1 2nd stage turbine disk and blades with an inspected turbine that does not incorporate mod TU 347 and is fitted with new blades or with a turbine that incorporates mod TU 347, using Turbomeca MSB No. A292 72 0807, Version E, dated October 29, 2009, paragraphs 2B(1)(c) or (d), or 2B(2)(b) or (c), at the following times: (1) Replace before further flight on engines with a 2nd stage turbine disk having accumulated more than 1,500 hours TIS since-new or since-last-inspection, whichever occurs later, or with 2nd stage turbine blades having accumulated more than 1,500 hours TIS since-new. (2) For engines with 2nd stage turbine blades having accumulated on the effective date of this AD, more than 900 hours TIS since-new, but 1,500 or fewer hours TIS since-new, replace before the 2nd stage turbine blades have accumulated 1,500 hours TIS since-new, or before the 2nd stage turbine disk has accumulated 1,500 hours TIS since-new, whichever occurs first. (3) For engines with 2nd stage turbine blades having accumulated on the effective date of this AD, 900 or fewer hours TIS since-new, replace before the 2nd stage turbine blades have accumulated 1,200 hours TIS since-new. Repetitive Replacements of 2nd Stage Turbines on Arriel 1D and 1D1 Engines (l) Thereafter, for 2nd stage turbines that do not incorporate mod TU 347, replace the 2nd stage turbine disk and blades before the blades have accumulated 1,200 hours TIS since-new. Relative Position Check Continuing Compliance Requirements (m) All 2nd stage turbines, including those that are new or overhauled, must continue to comply with the actions specified in paragraphs (f) and (g) of this AD, unless mod TU 347 has been incorporated. Optional Terminating Action (n) Installing a new turbine, P/N 0 292 25 039 0, (incorporation of mod TU 347) terminates the requirements to perform the repetitive actions specified in paragraphs (g), (j), and (l) of this AD. Alternative Methods of

This AD results from reports of new cases of failures of 2nd stage turbine blades since we issued AD 2008-07-01. We are issuing this AD to prevent the failure of 2nd stage turbine blades, which could result in an uncommanded in-flight engine shutdown, and a subsequent forced autorotation landing or accident.