# Airworthiness Directives; Safran Helicopter Engines, S.A. Turboshaft Engines
> **Rule** · Final rule. · Published 2017-03-09 · Effective 2017-04-13 · 82 FR 13062
## Document
- **Document number:** 2017-04634
- **Category:** airworthiness
- **Manufacturer:** Safran Helicopter
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 82 FR 13062
- **Publication date:** 2017-03-09
- **Effective date:** 2017-04-13
- **FAA docket:** Docket No. FAA-2016-7850
## Abstract

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.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2017/03/09/2017-04634/airworthiness-directives-safran-helicopter-engines-sa-turboshaft-engines)
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