Airworthiness Directive · Amendment 39-18819 · Safran Helicopter Engines, S.A. Turboshaft Engines
Safran Helicopter Engines, S.A. Turboshaft Engines
This AD applies to all Safran Helicopter Engines S.A. Arriel 2B turboshaft engines with a pre-modification (mod) TU 158 hydro-mechanical metering unit (HMU), installed.
We are adopting a new airworthiness directive (AD) for all Safran Helicopter Engines, S.A. Arriel 2B turboshaft engines. This AD requires removing any pre-modification (mod) TU 158 hydro-mechanical metering unit (HMU) and replacing with a part eligible for installation. This AD was prompted by a report of an uncommanded in- flight shutdown (IFSD) on a single-engine helicopter, caused by a low returning spring rate of the needle of the HMU. We are issuing this AD to correct the unsafe condition on these products.
(1) For an engine in pre-mod TU 158 configuration, within 200 engine hours, or within 5 months, whichever occurs first after the effective date of this AD, remove the pre-mod TU 158 HMU from service and replace it with a part eligible for installation.
(2) Reserved.
After the effective date of the AD, do not install any pre-mod TU 158 HMU into any engine.
For the purpose of this AD, an HMU eligible for installation is one that incorporates mod TU 158 in accordance with Safran Helicopter Engines, S.A. Mandatory Service Bulletin No. 292 73 3158, Version A, dated April 7, 2016, or other FAA-approved parts.
