[Docket No. FAA-2015-3805; Directorate Identifier 2015-NE-28-AD] 

RIN 2120-AA64 

Airworthiness Directives; Turbomeca S.A. Turboshaft Engines 

AGENCY: Federal Aviation Administration (FAA), DOT. 

ACTION: Notice of proposed rulemaking (NPRM). 

SUMMARY: We propose to adopt a new airworthiness directive (AD) for all 

Turbomeca S.A. ARRIEL 2C, 2Cl, 2C2, 2Sl, and 2S2 turboshaft engines with 

modification TU34 or TU34A installed. This proposed AD was prompted by torque 

conformation box (TCB) failures. This proposed AD would require inspecting the TCB 

for correct resistance values and removing TCBs that fail inspection before further flight. 

We are proposing this AD to prevent failure of the TCB which could lead to loss of 

engine thrust control and damage to the aircraft. 

DATES: We must receive comments on this proposed AD by [INSERT DATE 60 

DAYS AFTER DATE OF PUBLICATION IN THE FEDERAL REGISTER]. 

ADDRESSES: You may send comments by any of the following methods: 

• Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the 

instructions for submitting comments. 

• Mail: Docket Management Facility, U.S. Department of Transportation, 1200 

New Jersey Avenue SE., West Building Grm.md 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. 
England Executive Park, Burlington, MA. For information on the availability of this 

material at the FAA, call781-238-7125. 

Examining the AD Docket 

You may examine the AD docket on the Internet at http://www.regulations.gov by 

searching for and locating Docket No. FAA-2015-3805; 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 mandatory continuing 

airworthiness information (MCAI), the regulatory evaluation, any comments received, 

and other information. The address for the Docket Office (phone: 800-647-5527) is in the 

ADDRESSES section. Comments will be available in the AD docket shortly after receipt. 

FOR FURTHER INFORMATION CONTACT: Brian Kierstead, Aerospace Engineer, 

Engine Certification Office, FAA, Engine & Propeller Directorate, 12 New England 

Executive Park, Burlington, MA 01803; phone: 781-238-7772; fax: 781-238-7199; email: 

brian.kierstead@faa.gov. 

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. F AA-2015-3805; Directorate Identifier 2015-NE-28-AD" at the 

beginning of your comments. We specifically invite comments on the overall regulatory, 

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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. 

Discussion 

The European Aviation Safety Agency (EASA), which is the Technical Agent for 

the Member States of the European Community, has issued EASA AD 2015-0177, dated 

August 25, 2015 (referred to hereinafter as ''the MCAI"), to correct an unsafe condition 

for the specified products. The MCAI states: 

Several cases of torque conformation box (TCB) failures have 

been reported on engines incorporating mod TU34 or mod TU34A. 

Investigation concluded that these failures were caused by cracks 

on soldered joints ofTCB resistors. 

This condition, if not corrected, could lead to limited power 

availability in a One Engine Inoperative (OEI) case, possibly 

resulting in reduced control of the helicopter. 

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

the Internet at http://www.regulations.gov by searching for and locating Docket No. 

FAA-2015-3805. 

Related Service Information under 1 CFR Part 51 

Turbomeca S.A. has issued Mandatory Service Bulletin (MSB) No. 292 72 2860, 

Version A, dated July 15, 2015. The MSB describes procedures for checking TCB 

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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 the 

European Community, EASA has 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 inspecting the TCB for correct resistance values and removing TCBs 

that fail inspection. 

Costs of Compliance 

We estimate that this proposed AD affects 300 engines installed on helicopters of 

U.S. registry. We estimate that it would take about 1 hour to perform an 'inspection. We 

also estimate that 20% of these engines would fail the inspection and require TCB 

removal, which would take about 1 hour. The average labor rate is $85 per hour. Based 

on these figures, we estimate the cost of this proposed AD on U.S. operators to be 

$30,600, 

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. 

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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), 

(3) Will not affect intrastate aviation in Alaska to the extent that it justifies 

making a regulatory distinction, and 

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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. 

§ 39.13 [Amended] 

2. The FAA amends§ 39.13 by adding the following new airworthiness directive 

(AD): 

Turbomeca S.A.: Docket No. FAA-2015-3805; Directorate Identifier 2015-NE-28-AD. 

(a) Comments Due Date 

We must receive comments by [INSERT DATE 60 DAYS AFTER DATE OF 

PUBLICATION IN THE FEDERAL REGISTER]. 

(b) Affected ADs 

None. 

(c) Applicability 

This AD applies to Turbomeca S.A. ARRIEL 2C, 2Cl, 2C2, 2Sl, and 2S2 

turboshaft engines with modification TU34 or TU34A installed. 

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(e) Actions and Compliance 

Comply with this AD within the compliance times specified, unless already done. 

(1) Within 600 engine flight hours (EFHs) or 6 months after the effective date of 

this AD, whichever occurs first, check the resistance values on the TCB. Use 

Accomplishment Instructions, paragraph 2.3.2 of Turbomeca S.A. Mandatory Service 

Bulletin (MSB) 292 72 2860, Version A, dated July 15, 2015, to do the inspection. 

Repeat this inspection every 600 EFHs since last inspection. 

(2) Remove before further flight any TCB that fails the inspection required by 

paragraph (e)(l) of this AD. 

(f) Alternative Methods of Compliance (AMOCs) 

The Manager, Engine Certification Office, FAA, may approve AMOCs for this 

AD. Use the procedures found in 14 CFR 39.19 to make your request. You may email 

your request to: ANE-AD-AMOC@faa.gov. 

(g) Related Information 

(1) For more information about this AD, contact Brian Kierstead, Aerospace 

Engineer, Engine Certification Office, FAA, Engine & Propeller Directorate, 12 New 

England Executive Park, Burlington, MA 01803; phone: 781-238-7772; fax: 781-238-

7199; email: brian.kierstead@faa.gov. 

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(3) Turbomeca S.A. Mandatory Service Bulletin No. 292 72 2860, Version A, 

dated July 15,2015, can be obtained from Turbomeca S.A., using the contact information 

in paragraph (g)(4) of this proposed AD. 

(4) For service information identified in this proposed AD, contact Turbomeca 

S.A., 40220 Tamas, France; phone: 33 (0)5 59 74 40 00; fax: 33 (0)5 59 74 45 15. 

( 5) You may view this service information at the FAA, Engine & Propeller 

Directorate, 12 New England Executive Park, Burlington, MA. For information on the 

availability of this material at the FAA, call 781-238-7125. 

Issued in Burlington, Massachusetts, on October 28,2015. 

Colleen M. D' Alessandro, 

Directorate Manager, Engine & Propeller Directorate, 

Aircraft Certification Service. 

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