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2010-04-07: Engine

FAA order 2010-04-07 is an airworthiness directive in force since March 23, 2010. The FAA's subject line: Engine. It names the Turbomeca (Safran) ARRIEL 2S1 engine: about 30 aircraft on the U.S. register today, though an order usually covers particular versions or serial numbers rather than every one. System: engine.

What it applies to as the FAA lists it

Kind of product: Engine
Makes: Turbomeca S.A.
Models: Arriel 2S1
Engine series: Turbomeca (Safran) ARRIEL 2S1 30 aircraft

Dates and paperwork

In force since: March 23, 2010
Published: February 16, 2010 (signed February 8, 2010)
Docket: FAA-2009-0568
Status: Current
The FAA's document: Read the order on the FAA's site

The FAA's summary their words, unchanged

We are adopting a new airworthiness directive (AD) for the products listed above. This AD results from mandatory continuing airworthiness information (MCAI) issued by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as: During acceleration up to One Engine Inoperative (OEI) 30-second rating, one event of flight loss of full automatic control occurred on an Arriel 2S1 engine. The selection of OEI 30-second rating on engine 1 was triggered by the automatic detection of an OEI situation further to a transient deceleration of engine 2. The transient deceleration of engine 2 was caused by the untimely reset of its digital electronic control unit (DECU). Once this reset was completed, engine 2 resumed its nominal operation. Afterwards the aircraft then continued its flight safely with its engine 1 operating in manual control mode. The loss of full automatic control of engine 1 was caused by loss of steps of the stepper motor controlling the fuel metering valve inside the Hydro-mechanical Unit (HMU). It has been found that high accelerations, notably up to OEI 30- second rating, increase the risk of loss of steps of the HMU stepper motor. Therefore, this event has led to the consideration of the following unsafe condition at aircraft level: In-flight loss of full automatic control of the engine induced by the loss of steps of the stepper motor during acceleration up to OEI 30-second rating, further to an actual OEI situation on the other engine (such as a power loss event). We are issuing this AD to prevent loss of full automatic control of the engine during acceleration up to the OEI 30-second rating. This condition could result in reduced controllability of the helicopter.

The order itself the regulatory text, as published

Show the full text (2,838 characters)

2010-04-07 Turbomeca: Amendment 39-16200. Docket No. FAA-2009-0568; Directorate Identifier 2009-NE-20-AD. 

Effective Date 

	(a) This airworthiness directive (AD) becomes effective March 23, 2010. 

Affected ADs 

	(b) None. 

Applicability 

	(c) This AD applies to Turbomeca Arriel 2S1 turboshaft engines that have not incorporated Modification TU 109. These engines are installed on, but not limited to, Sikorsky S-76C twin-engine helicopters. 

Reason 

	(d) This AD results from mandatory continuing airworthiness information (MCAI) issued by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. We are issuing this AD to prevent loss of full automatic control of the engine during acceleration up to the One Engine Inoperative 30-second rating. This condition could result in reduced controllability of the helicopter. 

Actions and Compliance 

	(e) Unless already done, do the following actions: 
	(1) Within 350operating hours after the effective date of this AD, perform an upgrade of the digital electronic control unit (DECU) software to version 11.01, to implement modification TU 109. 
	(2) Guidance on implementing TU 109 can be found in Turbomeca Mandatory Service Bulletin No. 292 73 2109, Version E, dated September 17, 2008. 

Prohibition of Mixed DECU Software Versions on the Same Helicopter 

	(3) Do not operate an Arriel 2S1-powered twin-engine helicopter with one engine upgraded to modification TU 109 if the other engine is not upgraded to modification TU 109. 

FAA AD Differences 

	(f) This AD differs from the Mandatory Continuing Airworthiness Information (MCAI) and/or service information as follows: 
	(1) The MCAI requires performing the DECU software upgrade no later than August 31, 2010. 
	(2) This proposed AD would require performing the DECU software upgrade within 350 operating hours after the effective date of the proposed AD. 

Alternative Methods of Compliance (AMOCs) 

	(g) The Manager, Engine Certification Office, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. 

Related Information 

	(h) Refer to MCAI EASA Airworthiness Directive 2009-0010, dated January 20, 2009, and Turbomeca Mandatory Service Bulletin No. 292 73 2109, Version E, dated September 17, 2008, for related information. Contact Turbomeca, 40220 Tarnos, France; telephone (33) 05 59 74 40 00, fax (33) 05 59 74 45 15 for the service information identified in this AD. 
	(i) Contact Kevin Dickert, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; e-mail: kevin.dickert@faa.gov; telephone (781) 238-7117; fax (781) 238-7199, for more information about this AD. 

Material Incorporated by Reference 

	(j) None.

Source: FAA Dynamic Regulatory System, airworthiness directives. The FAA's document is the authority; the register counts are this site's, from the FAA register of October 5, 2026. Connections as data: /graph/directive/2010-04-07.json · aircraft systems.