E7-22330. Airworthiness Directives; Turbomeca Makila 1 A and 1 A1 Turboshaft Engines

AGENCY:

Federal Aviation Administration (FAA), Department of Transportation (DOT).

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to supersede an existing airworthiness directive (AD) for Turbomeca Makila 1 A, 1 A1, and 1 A2 turboshaft engines. That AD currently requires replacing certain digital electronic control units (DECUs) and electronic control units (ECUs) with modified DECUs and ECUs. This proposed AD would apply only to Makila 1 A and 1 A1 turboshaft engines, and would require replacing the selector-comparator board in the ECU with a board incorporating Turbomeca modification TU 250. This proposed AD results from recent unexplained reversions of the ECU to the 65% N1 back-up mode. We are proposing this AD to prevent dual-engine reversion of the ECU to the 65% N1 back-up mode, which could lead to inability to continue safe flight, emergency autorotation landing, or an accident.

DATES:

We must receive any comments on this proposed AD by January 14, 2008.

ADDRESSES:

Use one of the following addresses to comment on this proposed AD.

• 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].

Contact Turbomeca, 40220 Tarnos, France; telephone [phone]; fax [phone] for the service information identified in this proposed AD.

FOR FURTHER INFORMATION CONTACT:

Christopher Spinney, Aerospace Engineer, Engine Certification Office, FAA, Engine and 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 us any written relevant data, views, or arguments regarding this proposal. Send your comments to an address listed under ADDRESSES. Include “Docket No. FAA-2007-0157; Directorate Identifier 2001-NE-23-AD” in the subject line of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments received by the closing date and may amend the proposed AD in light of 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 proposed 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 July 23, 2002, we issued AD 2002-15-05, Amendment 39-12833 (67 FR 49859, August 1, 2002). That AD requires replacing certain DECUs and ECUs with modified DECUs and ECUs, on Turbomeca Makila 1 A, 1 A1, and 1 A2 turboshaft engines. The Direction Generale De L'Aviation Civile, which is the airworthiness authority for France, advised that incorporating Turbomeca Modification TU 203 to the ECUs that are used on the Makila 1 A and 1 A1 turboshaft engines, and incorporating Turbomeca Modification TU 205C to the DECUs used on the Makila 1 A2 turboshaft engines, improves failure detection of the ECU and simulates a fixed power turbine speed (Npt) if two of the three channels fail.

Actions Since AD 2002-15-05 Was Issued

Since AD 2002-15-05 was issued, The European Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Community, notified us that an unsafe condition may exist on Turbomeca Makila 1 A and 1 A1 turboshaft engines. EASA advises that recent unexplained reversions of the ECU to the 65% N1 back-up mode have occurred on these engines. Turbomeca postulates that these events can be caused by corruption of the engine N2 speed signals by short disturbances, such as electromagnetic interference, which can threaten both engines at the same time. The replacement of the selector-comparator board will allow recovery from the ECU 65% N1 back-up mode for temporary interruptions of the N2 signal.

Relevant Service Information

We have reviewed and approved the technical contents of Turbomeca Mandatory Service Bulletin (MSB) No. 298 73 0250, dated March 23, 2007, that describes procedures for replacing the selector-comparator board in the ECU with a board incorporating Turbomeca modification TU 250. The replacement board makes the ECU less sensitive to electromagnetic interference. EASA classified this service bulletin as mandatory and issued AD 2007-0144, dated May 18, 2007, in order to ensure the airworthiness of these Makila 1 A and 1 A1 turboshaft engines in Europe.

Makila 1 A2 Turboshaft Engines Excluded From This Proposed AD

Although Makila 1 A2 turboshaft engines, which were also listed in the previous AD, are affected by this unsafe condition, they are addressed by a different EASA AD. We will address those engines in another proposed AD.

Bilateral Agreement Information

These Makila 1 A and 1 A1 turboshaft engines are manufactured in France and are type certificated for operation in the United States under the provisions of Section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Under this bilateral airworthiness agreement, EASA kept us informed of the situation described above. We have examined the findings of EASA, reviewed all available information, and determined that AD action is necessary for products of this type design that are certificated for operation in the United States.

FAA's Determination and Requirements of the Proposed AD

We have evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other products of this same type design. We are proposing this AD, which would require replacing the selector-comparator board in the ECU with a board incorporating Turbomeca Modification TU 250.

Costs of Compliance

We estimate that this proposed AD would affect 10 Makila 1 A and 1 A1 turboshaft engines installed on helicopters of U.S. registry. We also estimate that it would take about 1 work-hour per engine to perform the proposed actions, and that the average labor rate is $80 per work-hour. Required parts would cost about $3,500 per engine. Based on these figures, we estimate the total cost of the proposed AD to U.S. operators to be $35,800.

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.

Docket Number Change

We are transferring the docket for this AD to the Federal Docket Management System as part of our on-going docket management consolidation efforts. The new Docket No. is FAA-2007-0157. The old Docket No. became the Directorate Identifier, which is 2001-NE-23-AD.

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 39-12833 (67 FR 49859, August 1, 2002) and by adding a new airworthiness directive, to read as follows:

Turbomeca: Docket No. FAA-2007-0157; Directorate Identifier 2001-NE-23-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this airworthiness directive (AD) action by January 14, 2008.

Affected ADs

(b) This AD supersedes AD 2002-15-05, Amendment 39-12833.

Applicability

(c) This AD applies to Turbomeca Makila 1 A and 1 A1 turboshaft engines. These engines are installed on, but not limited to, Eurocopter France model AS 332C, AS 332L, and AS 332L1 helicopters.

Unsafe Condition

(d) This AD results from recent unexplained reversions of the ECU to the 65% N1 back-up mode. The actions specified in this AD are intended to prevent dual-engine reversion of the ECU to the 65% N1 back-up mode, which could lead to inability to continue safe flight, emergency autorotation landing, or an accident.

Compliance

(e) You are responsible for having the actions required by this AD performed before June 30, 2008, unless the actions have already been done.

(f) Replace the Selector-Comparator board in the ECU with a board incorporating Turbomeca Modification TU 250. Information on Modification TU 250 can be found in Turbomeca Mandatory Service Bulletin No. 298 73 0250, dated March 23, 2007.

Alternative Methods of Compliance

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

Related Information

(h) European Aviation Safety Agency AD 2007-0144, dated May 18, 2007, also addresses the subject of this AD.

(i) Contact Christopher Spinney, Aerospace Engineer, Engine Certification Office, FAA, Engine and 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 November 8, 2007.

Peter A. White,

Assistant Manager, Engine and Propeller Directorate, Aircraft Certification Service.