Document ID: FAA-2009-0568-0001
Agency: faa
Document Type: Rule
Title: Airworthiness Directives; Turbomeca Arriel 2S1 Turboshaft Engines
Posted Date: 2009-10-28T04:00Z

[Federal Register: October 28, 2009 (Volume 74, Number 207)]
[Proposed Rules]               
[Page 55491-55493]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr28oc09-21]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2009-0568; Directorate Identifier 2009-NE-20-AD]
RIN 2120-AA64

 
Airworthiness Directives; Turbomeca Arriel 2S1 Turboshaft Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to adopt a new airworthiness directive (AD) for the 
products listed above. This proposed 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 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 
Hydromechanical 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 proposing 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.

DATES: We must receive comments on this proposed AD by November 27, 
2009.

ADDRESSES: You may send comments by any of the following methods:
     Federal eRulemaking Portal: Go to http://
www.regulations.gov and follow the instructions for sending your 
comments electronically.
     Mail: Docket Management Facility, U.S. Department of 
Transportation, 1200 New Jersey Avenue, SE., West Building Ground 
Floor, Room W12-140, Washington, DC 20590-0001.
     Hand Delivery: Deliver to Mail address above between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
     Fax: (202) 493-2251.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://
www.regulations.gov; or in person at the Docket Operations office 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The AD docket contains this proposed AD, the regulatory 
evaluation, any comments received, and other information. The street 
address for the Docket Operations office (telephone (800) 647-5527) is 
the same as the Mail address provided in the ADDRESSES section. 
Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: James Lawrence, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803; e-mail: 
james.lawrence@faa.gov; telephone (781) 238-7176; fax (781) 238-7199.
    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.

SUPPLEMENTARY INFORMATION: 

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about this proposed AD. Send your comments to an address 
listed under the ADDRESSES section. Include ``Docket No. FAA-2009-0568; 
Directorate Identifier 2009-NE-20-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of this proposed AD. We 
will consider all comments received by the closing date and may amend 
this proposed AD based on those comments.
    We will post all comments we receive, without change, to http://
www.regulations.gov, including any personal information you provide. We 
will also post a report summarizing each substantive verbal contact 
with FAA personnel concerning this proposed AD. Using the search 
function of the Web site, anyone can find and read the comments in any 
of our dockets, including, if provided, the name of the individual who 
sent the comment (or signed the comment on behalf of an association, 
business, labor union, etc.). You may review the DOT's complete Privacy 
Act Statement in the Federal Register published on April 11, 2000 (65 
FR 19477-78).

Discussion

    The European Aviation Safety Agency (EASA), which is the Technical 
Agent for the Member States of the European Community, has issued EASA 
Airworthiness Directive 2009-0010, dated January 20, 2009 (referred to 
after this as ``the MCAI''), to correct an unsafe condition for the 
specified products. The MCAI states:

    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 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

[[Page 55492]]

motor controlling the fuel metering valve inside the Hydromechanical 
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).

You may obtain further information by examining the MCAI in the AD 
docket.

FAA's Determination and Requirements of This Proposed AD

    This product has been approved by the aviation authority of France 
and is approved for operation in the United States. Pursuant to our 
bilateral agreement with France, they have notified us of the unsafe 
condition described in the MCAI and service information referenced 
above. We are proposing this AD because we evaluated all information 
provided by EASA and determined the unsafe condition exists and is 
likely to exist or develop on other products of the same type design. 
This proposed AD would require upgrading the DECU software to version 
11.01, to implement modification of TU 109. Modification TU 109 
increases the tolerance to loss of steps of the control system. It 
reduces significantly the risk of loss of full automatic control due to 
loss of steps of the stepper motor, notably during engine accelerations 
up to OEI 30-second rating.

Differences Between This AD and the MCAI or Service Information

    The MCAI requires performing the DECU software upgrade no later 
than August 31, 2010. This proposed AD would require performing the 
DECU software upgrade within 350 operating hours after the effective 
date of the proposed AD.

Costs of Compliance

    Based on the service information, we estimate that this proposed AD 
would affect about 136 products of U.S. registry. We also estimate that 
it would take about 3 work-hours per product to comply with this 
proposed AD. The average labor rate is $80 per work-hour. Required 
parts would cost about $3,500 per product. Based on these figures, we 
estimate the cost of the proposed AD on U.S. operators to be $508,640. 
Our cost estimate is exclusive of possible warranty coverage.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, section 106, describes the 
authority of the FAA Administrator. ``Subtitle VII: Aviation 
Programs,'' describes in more detail the scope of the Agency's 
authority.
    We are issuing this rulemaking under the authority described in 
``Subtitle VII, Part A, Subpart III, Section 44701: General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

Regulatory Findings

    We determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD would not 
have a substantial direct effect on the States, on the relationship 
between the national Government and the States, or on the distribution 
of power and responsibilities among the various levels of government.
    For the reasons discussed above, I certify this proposed 
regulation:
    1. Is not a ``significant regulatory action'' under Executive Order 
12866;
    2. Is not a ``significant rule'' under the DOT Regulatory Policies 
and Procedures (44 FR 11034, February 26, 1979); and
    3. Will not have a significant economic impact, positive or 
negative, on a substantial number of small entities under the criteria 
of the Regulatory Flexibility Act.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this proposed AD and placed it in the AD docket.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

    1. The authority citation for part 39 continues to read as follows:

    Authority:  49 U.S.C. 106(g), 40113, 44701.

Sec.  39.13  [Amended]

    2. The FAA amends Sec.  39.13 by adding the following new AD:

Turbomeca: Docket No. FAA-2009-0568; Directorate Identifier 2009-NE-
20-AD.

Comments Due Date

    (a) We must receive comments by November 27, 2009.

Affected Airworthiness Directives (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 350 operating 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,

[[Page 55493]]

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 James Lawrence, Aerospace Engineer, Engine 
Certification Office, FAA, Engine and Propeller Directorate, 12 New 
England Executive Park, Burlington, MA 01803; e-mail: 
james.lawrence@faa.gov; telephone (781) 238-7176; fax (781) 238-
7199, for more information about this AD.

    Issued in Burlington, Massachusetts, on October 1, 2009.
Peter A. White,
Assistant Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. E9-25943 Filed 10-27-09; 8:45 am]

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