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Proposed Rule

Airworthiness Directives; Turbomeca Turmo IV A and IV C Series Turboshaft Engines

Document Details

Information about this document as published in the Federal Register.

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Start Preamble

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to supersede an existing airworthiness directive (AD) for Turbomeca Turmo IV A and IV C series turboshaft engines. That AD currently requires borescope and eddy current inspections or ultrasonic inspections of centrifugal compressor intake wheel blades for cracks and evidence of corrosion pitting, and replacement with serviceable parts. This proposed AD would require the same actions, but would require borescope inspections at more frequent intervals for certain engines. This proposed AD results from Turbomeca's review of the engines' service experience that determined more frequent borescope inspections are required on engines not modified to the TU 191, TU 197, or TU 224 standard. We are proposing this AD to prevent centrifugal compressor intake wheel blade cracks, which can result in engine in-flight power loss, engine shutdown, or forced landing.

DATES:

We must receive any comments on this proposed AD by April 10, 2006.

ADDRESSES:

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

  • By mail: Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 99-NE-12-AD, 12 New England Executive Park, Burlington, MA 01803-5299.
  • By fax: (781) 238-7055.
  • By e-mail: 9-ane-adcomment@faa.gov.

You can get the service information identified in this proposed AD from Turbomeca, 40220 Tarnos, France; telephone 33 05 59 74 40 00, fax 33 05 59 74 45 15.

You may examine the AD docket, by appointment, at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA.

Start Further Info

FOR FURTHER INFORMATION CONTACT:

Christopher Spinney, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone (781) 238-7175; fax (781) 238-7199.

End Further Info End Preamble Start Supplemental Information

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or arguments regarding this proposal. Send your comments to an address listed under ADDRESSES. Include “AD Docket No. 99-NE-12-AD” in the subject line of your comments. If you want us to acknowledge receipt of your mailed comments, send us a self-addressed, stamped postcard with the docket number written on it; we will date-stamp your postcard and mail it back to you. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. If a person contacts us verbally, and that contact relates to a substantive part of this proposed AD, we will summarize the contact and place the summary in the docket. We will consider all comments received by the closing date and may amend the proposed AD in light of those comments.

Examining the AD Docket

You may examine the AD Docket (including any comments and service information), by appointment, between 8 a.m. and 4:30 p.m., Monday through Friday, except Federal holidays. See ADDRESSES for the location.

Discussion

On May 20, 2003, the FAA issued AD 2003-11-09, Amendment 39-13168 (68 FR 31970, May 29, 2003). That AD requires initial and repetitive borescope and eddy current inspections or ultrasonic inspections of centrifugal compressor intake wheel blades for cracks and evidence of corrosion pitting, and, if found cracked or if there is evidence of corrosion pitting, replacement with serviceable parts. The Direction Generale de L'Aviation Civile (DGAC), which is the airworthiness authority for France, notified the FAA that an unsafe condition may exist on Turbomeca Turmo IV A and IV C series turboshaft engines. The DGAC advises that they have received reports of cracked centrifugal compressor intake wheel blades.

The phenomena of blade cracking occurs in two phases; initiation after a single event, such as foreign object damage or surge, and crack propagation due to operating at a gas generator speed, between 80 percent and 83 percent, which sets up a vibration. Although the exact cause of the initiation of cracks has not yet been identified, cracks could initiate at corrosion pits. The investigation is continuing. This condition, if not corrected, could result in centrifugal compressor intake wheel blade cracks, which can result in engine in-flight power loss, engine shutdown, or forced landing.

Since AD 2003-11-09 required the removal of the TU 197 standard within 6 months after the AD's effective date of July 3, 2003, the TU 197 standard is no longer allowed. The compliance time in this proposed AD requires removing the TU 197 standard before further flight.

Actions Since AD 2003-11-09 Was Issued

Since AD 2003-11-09 was issued, Turbomeca reevaluated the engines' service experience and reduced the borescope inspection interval for engines not modified to the TU 191, TU 197, or TU 224 standard, from 250 flight hours-since-last inspection to 200 flight hours-since-last inspection. Also, Start Printed Page 6692Turbomeca eliminated the TU 197 standard as a valid modification.

Relevant Service Information

We have reviewed and approved the technical contents of Turbomeca Mandatory Service Bulletin (MSB) A249 72 0100, Update No. 5, dated February 25, 2005, that describes procedures for the centrifugal compressor intake wheel blade borescope inspections. The DGAC classified this MSB as mandatory and issued AD F-2005-037, dated March 2, 2005, in order to ensure the airworthiness of these engines in France.

Bilateral Agreement Information

This engine model is manufactured in France and is 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. In keeping with this bilateral airworthiness agreement, the DGAC has kept the FAA informed of the situation described above. We have examined the findings of the DGAC, 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. Therefore, we are proposing this AD, which would require:

  • For engines modified to the TU 197 standard but not to the TU 191 standard or TU 224 standard, before further flight, removing the TU 197 standard and installing the TU 224 standard.
  • Initial and repetitive borescope and eddy current or ultrasonic inspections of centrifugal compressor intake wheel blades for cracks and evidence of corrosion pitting.
  • Removing centrifugal compressor intake wheel blades confirmed cracked or pitted.

The proposed AD would require that you do these actions using the service information described previously.

Costs of Compliance

We estimate that this proposed AD would affect 36 Turbomeca Turmo IV A and IV C series turboshaft engines installed on helicopters of U.S. registry. We also estimate that it would take about 41 work hours per engine to perform the proposed inspections, including disassembling and assembling engines, and that the average labor rate is $65 per work hour. A replacement centrifugal compressor assembly costs about $21,651. Based on these figures, the cost per inspection and replacement is estimated to be $24,316. Based on these figures, we estimate the total cost of the proposed AD to U.S. operators to be $875,390.

Special Flight Permits Paragraph Removed

Paragraph (e) of the current AD, AD 2003-11-09, contains a paragraph pertaining to special flight permits. Even though this proposed AD does not contain a similar paragraph, we have made no changes with regard to the use of special flight permits to operate the helicopter to a repair facility to do the work required by this AD. In July 2002, we published a new Part 39 that contains a general authority regarding special flight permits and airworthiness directives; see Docket No. FAA-2004-8460, Amendment 39-9474 (69 FR 47998, July 22, 2002). Thus, when we now supersede ADs we will not include a specific paragraph on special flight permits unless we want to limit the use of that general authority granted in section 39.23.

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 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. 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 summary of the costs to comply with this proposal and placed it in the AD Docket. You may get a copy of this summary by sending a request to us at the address listed under ADDRESSES. Include “AD Docket No. 99-NE-12-AD” in your request.

Start List of Subjects

List of Subjects in 14 CFR Part 39

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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:

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PART 39—AIRWORTHINESS DIRECTIVES

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

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

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[Amended]

2. The FAA amends § 39.13 by removing Amendment 39-13168 (68 FR 31970, May 29, 2003) and by adding a new airworthiness directive, to read as follows:

Turbomeca: Docket No. 99-NE-12-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this airworthiness directive (AD) action by April 10, 2006.

Affected ADs

(b) This AD supersedes AD 2003-11-09, Amendment 39-39-13168.

Applicability

(c) This AD applies to Turbomeca Turmo IV A and IV C series turboshaft engines. These engines are installed on but not limited to Aerospatiale SA 330—PUMA helicopters.

Unsafe Condition

(d) This AD results from Turbomeca's review of the engines' service experience that determined more frequent borescope inspections are required on engines not modified to the TU 191, TU 197, or TU 224 standard. The actions specified in this AD are Start Printed Page 6693intended to prevent centrifugal compressor intake wheel blade cracks, which can result in engine in-flight power loss, engine shutdown, or forced landing.

Compliance

(e) You are responsible for having the actions required by this AD performed within the compliance times specified unless the actions have already been done.

Engine Modification Before Further Flight

(f) For engines modified to the TU 197 standard but not to the TU 191 or TU 224 standard, before further flight, remove the TU 197 standard and install the TU 224 standard.

Initial Inspections

(g) For all engines, borescope-inspect, and either eddy current-inspect (ECI) or ultrasonic-inspect (UI) the centrifugal compressor intake wheel blades using paragraphs 2.B.(1)(a) through 2.B.(1)(g) of Turbomeca Mandatory Service Bulletin A249 72 0100, Update No. 5, dated February 25, 2005, and the criteria in the following Table 1:

Table 1.—Inspection Criteria

If engine modification level is:Then borescope-inspect centrifugal compressor intake wheel blades:Were traces of corrosion found at borescope-inspection?Then confirm corrosion by performing ECI or UI within:
(1) Pre TU 191 and Pre TU 224Within 200 flight hours-since-last inspection(i) YesSix months-or 50 flight hours-since-borescope inspection, whichever occurs first.
(ii) NoTwo hundred flight hours-since-borescope inspection.
(2) Post TU 191 or Post TU 224Within 1,000 flight hours-since-last inspection(i) YesSix months-or 50 flight hours-since-borescope inspection, whichever occurs first.
(ii) NoOne thousand flight hours-since-borescope inspection.

(h) Thereafter, perform repetitive inspections using the criteria in Table 1 of this AD.

(i) Remove centrifugal compressor intake wheel blades confirmed cracked or pitted.

Alternative Methods of Compliance

(j) The Manager, Engine Certification Office, 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

(k) Direction Generale de L'Aviation Civile airworthiness directive F-2005-037, dated March 2, 2005, also addresses the subject of this AD.

Start Signature

Issued in Burlington, Massachusetts, on February 3, 2006.

Peter A. White,

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

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[FR Doc. E6-1768 Filed 2-8-06; 8:45 am]

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