Airworthiness Directive · Amendment 39-16953 · Turbomeca S.A. Turboshaft Engines
Turbomeca S.A. Turboshaft Engines
Superseded. A later AD replaced this one: AD 2018-12-01. Comply with the one in force.
This AD applies to all Turbomeca S.A. Arriel 2B and 2B1 turboshaft engines.
We are superseding an existing airworthiness directive (AD) for all Turbomeca S.A. Arriel 2B and 2B1 turboshaft engines. That AD currently requires checking the transmissible torque between the low- pressure (LP) pump impeller and the high-pressure (HP) pump shaft on high-pressure/low-pressure (HP/LP) pump hydro-mechanical metering units (HMUs) that do not incorporate Modification TU 147. This new AD requires inspection and possible replacement of the HMU. This AD was prompted by three additional cases of uncoupling of the HP/LP pump HMU LP fuel pump impeller and the HP fuel pump shaft, since the existing AD was issued. We are issuing this AD to prevent an uncommanded in-flight shutdown, which can result in a forced autorotation landing or accident.
(1) Check the transmissible torque between the LP fuel pump impeller and the HP fuel pump shaft as follows:
(i) For HMUs that do not incorporate Modification TU 147, check the torque before accumulating 500 engine flight hours (EFH) since March 11, 2010 (the effective date of AD 2010-03-06 (75 FR 5689, February 4, 2010)). Use Paragraph 2 of Turbomeca Alert Mandatory Service Bulletin (MSB) No. A292 73 2830, Version B, dated July 10, 2009, to do the check.
(ii) For HMUs that incorporated Modification TU 147 on or before March 31, 2010 and those HMUs that are not listed in Figures 2 or 3 of Turbomeca Alert MSB No. A292 73 2836, Version A, dated August 17, 2010:
(A) Check the torque within 750 EFH from the effective date of this AD, but no later than 14 months after the effective date of this AD.
(B) Use Paragraph 2 of Turbomeca Alert MSB No. A292 73 2836, Version A, dated August 17, 2010, to do the check.
(2) If the HMU does not pass the torque check, then replace the HMU with an HMU that is eligible for installation.
Do not install any HMU removed from service by this AD until it has been checked in accordance with Paragraph 2 of Turbomeca Alert MSB No. A292 73 2836, Version A, dated August 17, 2010, or checked in accordance with Paragraph 2 of Turbomeca Alert MSB No. A292 73 2830, Version B, dated July 10, 2009, and found eligible for installation.
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.
