# Airworthiness Directives; Turbomeca Arriel 1B, 1D, 1D1, and 1S1 Turboshaft Engines
> **Rule** · Final rule. · Published 2010-05-17 · Effective 2010-06-21 · 75 FR 27411
## Document
- **Document number:** 2010-10720
- **Category:** airworthiness
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 75 FR 27411
- **Publication date:** 2010-05-17
- **Effective date:** 2010-06-21
- **FAA docket:** Docket No. FAA-2005-21242
## Abstract

The FAA is superseding an existing airworthiness directive (AD) for certain Turbomeca Arriel 1B, 1D, 1D1, and 1S1 turboshaft engines. That AD requires initial and repetitive relative position checks of the gas generator 2nd stage turbine blades on Turbomeca Arriel 1B (that incorporate Turbomeca Modification (mod) TU 148), Arriel 1D, 1D1, and 1S1 turboshaft engines that do not incorporate mod TU 347. That AD also requires initial and repetitive replacements of 2nd stage turbines on Arriel 1B, 1D, and 1D1 engines. This AD requires lowering the initial and repetitive thresholds for replacement of 2nd stage turbines on Arriel 1B, 1D, and 1D1 engines. 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.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2010/05/17/2010-10720/airworthiness-directives-turbomeca-arriel-1b-1d-1d1-and-1s1-turboshaft-engines)
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