2010-6179. Airworthiness Directives; Turbomeca Arriel 2B1 Turboshaft Engines

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to revise an existing airworthiness directive (AD) for Turbomeca Arriel 2B1 turboshaft engines. 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: Since the issuance of AD 2007-0126 Turboméca has released modification TU157 which consists in modifying the pressure relief valve of the HMU by introducing a damping device into the valve. Introduction of this device has demonstrated to decrease the pressure fluctuations in the system, therefore reducing significantly the risk of wear of the delta-P diaphragm fabric. This will delete the need for a periodical replacement of the delta-P diaphragm before overhaul of the HMU. The modification TU157 is therefore considered as the terminating action for this AD.

We are proposing this AD to prevent the loss of automatic control mode coupled with the deteriorated performance of the backup mode, which can lead to the inability to continue safe flight, forced autorotation landing, or an accident.

DATES:

We must receive any comments on this proposed AD by April 21, 2010.

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: [phone].

FOR FURTHER INFORMATION CONTACT:

Kevin Dickert, Aerospace Engineer, Engine Certification Office, FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; e-mail: [e-mail]; telephone [phone]; fax [phone].

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-2007-27009; Directorate Identifier 2007-NE-02-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).

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 AD, the regulatory evaluation, any comments received, and other information. The street address for the Docket Operations office (telephone [phone]) is the same as the Mail address provided in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

Discussion

On September 11, 2007, the FAA issued AD 2007-19-09, Amendment 39-15200 (72 FR 53112, September 18, 2007). That AD requires initial and repetitive replacement of the hydromechanical metering unit (HMU) with a serviceable HMU every 1,500 operating hours. The European Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Community, has issued EASA Airworthiness Directive 2007-0126, dated May 7, 2007, (referred to after this as “the MCAI”), to correct an unsafe condition for the specified products. The MCAI states:

This AD is prompted by several reported cases of rupture of the constant delta pressure valve diaphragm on Arriel 2B1 engines, due to the wear of the delta-P diaphragm fabric. Rupture can result in the loss of the automatic control mode of the helicopter, accompanied with a deterioration of the behavior of the auxiliary back-up mode (emergency mode). On a single-engine helicopter, the result may be an emergency landing or, at worst, an accident.

This AD supersedes AD EASA AD 2007-0006 which required the removal from service of all the delta pressure valve diaphragms logging more than 2,000 hours-since-new.

Since issuance of EASA AD 2007-0006, no further case of rupture of the constant delta pressure valve diaphragm has been reported on Arriel 2 engines. However, about 40 additional diaphragms returning from service have been inspected by Turbomeca, and some signs of wear have been detected on diaphragms having logged less than 2,000 hours. Based on the inspection results, it has been decided to decrease this limit from 2,000 hours to 1,500 hours in order to further reduce the probability of delta-P diaphragm rupture.

Actions Since AD 2007-19-09 Was Issued

Since that AD was issued, the EASA has issued MCAI AD 2009-0091, dated May 4, 2009. The MCAI states:

Since the issuance of AD 2007-0126 Turboméca has released modification TU157 which consists in modifying the pressure relief valve of the HMU by introducing a damping device into the valve.

Introduction of this device has demonstrated to decrease the pressure fluctuations in the system, therefore reducing significantly the risk of wear of the delta-P diaphragm fabric. This will delete the need for a periodical replacement of the delta-P diaphragm before overhaul of the HMU. The modification TU157 is therefore considered as the terminating action for this AD.

This AD supersedes AD 2007-0126 by retaining the same requirements as in AD 2007-0126 except that:

• In addition to the ARRIEL 2B1 engines, applicability is extended to the ARRIEL 2B1A engines, which share the same HMU design.
• Applicability is limited to ARRIEL 2B1 and 2B1A engines that do not incorporate modification TU157.

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

Relevant Service Information

Turbomeca S.A. has issued Mandatory Service Bulletin No. 292 73 2818, Original Issue, dated October 18, 2006 and Update 1, dated April 3, 2007. The actions described in this service information are intended to correct the unsafe condition identified in the MCAI.

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 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 initial and repetitive replacement of the HMU with a serviceable HMU every 1,500 hours-since-new, hours-since-last-overhaul (HSO), or since incorporation of Turbomeca Service Bulletin (SB) No. 292 73 2105, whichever occurs later.

Differences Between This AD and the MCAI or Service Information

The MCAI applies to the ARRIEL 2B1 and 2B1A engines. The ARRIEL 2B1A engine is not type certificated in the United States, so this proposed AD applies to the ARRIEL 2B1 engine model only.

Costs of Compliance

Based on the service information, we estimate that this proposed AD would affect about 103 products of U.S. registry. We also estimate that it would take about 0.75 work-hour per product to comply with this proposed AD. The average labor rate is $85 per work-hour. Required parts would cost about $10,550 per product. Based on these figures, we estimate the cost of the proposed AD on U.S. operators to be $1,093,216.

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 have 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 that the proposed AD:

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. Would 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. See the ADDRESSES section for a location to examine the regulatory evaluation.

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 Federal Aviation Administration 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 removing Amendment 39-15200 (72 FR 53112, September 18, 2007) and by adding a new airworthiness directive, to read as follows:

Turbomeca: Docket No. FAA-2007-27009; Directorate Identifier 2007-NE-02-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this airworthiness directive (AD) action by April 21, 2010.

Affected ADs

(b) This AD revises AD 2007-19-09.

Applicability

(c) This AD applies to Turbomeca ARRIEL 2B1 turboshaft engines that don't incorporate modification TU157. These engines are installed on, but not limited to, Eurocopter AS 350 B3 and EC 130 B4 helicopters.

Reason

(d) European Aviation Safety Agency (EASA) AD No. 2009-0091, dated May 4, 2009, states:

Since the issuance of AD 2007-0126 Turboméca has released modification TU157 which consists in modifying the pressure relief valve of the HMU by introducing a damping device into the valve. Introduction of this device has demonstrated to decrease the pressure fluctuations in the system, therefore reducing significantly the risk of wear of the delta-P diaphragm fabric. This will delete the need for a periodical replacement of the delta-P diaphragm before overhaul of the HMU. The modification TU157 is therefore considered as the terminating action for this AD.

We are issuing this AD to prevent the loss of automatic control mode coupled with the deteriorated performance of the backup mode, which can lead to the inability to continue safe flight, forced autorotation landing, or an accident.

Actions and Compliance

(e) Unless already done, do the following actions.

(1) For ARRIEL 2B1 engines that incorporate modification TU157, no further action is required.

(2) For all other ARRIEL 2B1 engines do the following:

(i) Replace the hydromechanical metering unit (HMU) with a serviceable HMU before the HMU accumulates 1,500 hours-since-new, hours-since-last-overhaul (HSO), or since incorporation of Turbomeca Service Bulletin (SB) No. 292 73 2105, whichever occurs later.

(ii) Thereafter, replace the HMU with a serviceable HMU at every 1,500 hours-since new, since last overhaul, or since incorporation of Turbomeca SB No. 292 73 2105, whichever occurs later.

(iii) For the purposes of this AD, a serviceable HMU is an HMU fitted with a new constant delta P diaphragm in accordance with Turbomeca Mandatory Service Bulletin (MSB) No. 292 73 2818, Original Issue, Dated October 18, 2006, or Update No. 1, dated April 3, 2007.

Optional Terminating Action

(3) Replacing the HMU with an HMU that has been modified to TU157 terminates the repetitive requirement of paragraph (e)(2)(ii) of this AD.

FAA AD Differences

(f) This AD differs from the Mandatory Continuing Airworthiness Information (MCAI) because the MCAI applies to the ARRIEL 2B1 and 2B1A engines. The ARRIEL 2B1A engine is not type certificated in the United States, so this proposed AD applies to the ARRIEL 2B1 engine model only.

Other FAA AD Provisions

(g) Alternative Methods of Compliance (AMOCs): 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) Contact Kevin Dickert, Aerospace Engineer, Engine Certification Office, FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; e-mail: [e-mail]; telephone [phone]; fax [phone], for more information about this AD.

Issued in Burlington, Massachusetts on March 15, 2010.

Francis A. Favara,

Manager, Engine and Propeller Directorate, Aircraft Certification Service.