Airworthiness Directives; Honeywell International Inc. TFE731-2 and -3 Series Turbofan Engines

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for Honeywell International Inc. (formerly AlliedSignal Inc. and Garrett Turbine Engine Co.) TFE731-2 and -3 series turbofan engines with certain part number (P/N) low pressure turbine (LPT) stage 1 disks installed. This proposed AD would require for TFE731-2 and -2C series engines, initial and repetitive measurements and calculations to determine acceptance, and adjustment or replacement if necessary, of the LPT stage 1 nozzle assembly. This proposed AD would also require for TFE731-3, -3A, -3AR, -3B, -3BR, and -3R series engines, replacement of LPT stage 1 disks with serviceable disks. This proposed AD also allows replacement of the LPT stage 1 disk with a disk having a part number not listed in the proposed AD as optional terminating action to the repetitive actions. This proposal results from a report of an uncontained failure of the LPT stage 1 disk installed in a TFE731-3-1H turbofan engine. We are proposing this AD to prevent additional uncontained failure of the LPT stage 1 disk, and possible damage to the airplane.

DATES:

We must receive any comments on this proposed AD by August 16, 2004.

ADDRESSES:

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

• DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
• Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
• Mail: Docket Management Facility; U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, Washington, DC 20590-0001.
• Fax: (202) 493-2251.
• Hand Delivery: Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

You can get the service information identified in this proposed AD from Honeywell Engines and Systems (formerly AlliedSignal Inc. and Garrett Turbine Engine Co.) Technical Publications and Distribution, M/S 2101-201, P.O. Box 52170, Phoenix, AZ 85072-2170; telephone: (602) 365-2493 (General Aviation), (602) 365-5535 (Commercial Aviation), fax: (602) 365-5577 (General Aviation), (602) 365-2832 (Commercial Aviation).

You may examine the comments on this proposed AD in the AD docket on the Internet at http://dms.dot.gov.

FOR FURTHER INFORMATION CONTACT:

Joseph Costa, Aerospace Engineer, Los Angeles Aircraft Certification Office, FAA, Transport Airplane Directorate, 3960 Paramount Blvd., Lakewood, CA 90712-4137; telephone: (562) 627-5246; fax: (562) 627-5210.

SUPPLEMENTARY INFORMATION:

Docket Management System (DMS)

We have implemented new procedures for maintaining AD dockets electronically. As of May 17, 2004, we posted new AD actions on the DMS and assigned a DMS docket number. We track each action and assign a corresponding Directorate identifier. The DMS docket No. is in the form “Docket No. FAA-200X-XXXXX.” Each DMS docket also lists the Directorate identifier (“Old Docket Number”) as a cross-reference for searching purposes.

Comments Invited

We invite you to submit any written relevant data, views, or arguments regarding this proposal. Send your comments to an address listed under ADDRESSES. Include “Docket No. FAA-2004-18019; Directorate Identifier 2003-NE-65-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://dms.dot.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 DMS web site, anyone can find and read the comments in any of our dockets, including 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) or you may visit http://dms.dot.gov.

We are reviewing the writing style we currently use in regulatory documents. We are interested in your comments on whether the style of this document is clear, and your suggestions to improve the clarity of our communications that affect you. You can get more information about plain language at http://www.faa.gov/language and http://www.plainlanguage.gov.

Examining the AD Docket

You may examine the docket that contains the proposal, any comments received, and any final disposition in person at the DMS Docket Offices between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Office (telephone (800) 647-5227) is located on the plaza level of the Department of Transportation Nassif Building at the street address stated in ADDRESSES. Comments will be available in the AD docket shortly after the DMS receives them.

Discussion

In June of 2003, we became aware of a report of a TFE731-3-1H turbofan engine that experienced an uncontained failure of LPT stage 1 disk, P/N 3072351-5. Analysis by the manufacturer revealed that the disk, which only had 107 hours of operation accumulated since new, failed due to vibration-induced high-cycle-fatigue (HCF) cracking in the web area of the disk. Analysis and testing of these vibrations have revealed that the disk design is sensitive to significant nozzle throat-area variations such as those caused by inappropriate maintenance of the vanes of the LPT stage 1 nozzle assembly. Two other uncontained disk failures involving TFE731-3 series engines occurred over the past 16 years and were considered at the time to have been caused by inappropriate maintenance practices performed on the LPT stage 1 nozzle assembly. We have determined that similarly designed LPT stage 1 disks, P/Ns 3072070-All, 3072351-All, 3073013-All, 3073113-All, 3073497-All, and 3074103-All, (where All denotes all dash numbers), are sensitive for the same reasons described for disk P/N 3072351-5. This condition, if not corrected, could result in uncontained failure of the LPT stage 1 disk, and possible damage to the airplane.

Relevant Service Information

We have reviewed and approved the technical contents of Honeywell International Inc. Service Bulletin No. TFE731-72-3369RWK, Revision 6, dated June 26, 2002, that describes procedures for inspection, measurement and adjustment, or replacement if necessary, of the LPT stage 1 nozzle assembly. These procedures reduce the potential for vibration-induced HCF cracking in the web area of the disk.

Differences Between the Proposed AD and the Manufacturer's Service Information

Although Honeywell International Inc. SB No. TFE731-72-3369RWK, Revision 6, dated June 26, 2002, requires the inspections, measurements and adjustments, and replacements of the LPT stage 1 nozzle assembly to be done by certain approved repair stations, this proposed AD allows the actions to be done by any repair station certificated to perform the repair work.

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 TFE731-2 and -2C series engines with LPT stage 1 disk, P/Ns 3072070-All, or 3073013-All, (where All denotes all dash numbers) installed, initial and repetitive measurements and calculations to determine the acceptance, and adjustment or replacement if necessary of the LPT stage 1 nozzle assembly. These actions are to be done at the next major periodic inspection (MPI) or at next access to the LPT stage 1 nozzle assembly, whichever occurs first, but not to exceed 2,200 hours time-in-service (TIS) since the last LPT stage 1 nozzle assembly inspection.
• For TFE731-3, -3A, -3AR, -3B, -3BR, and -3R series engines with LPT stage 1 disk, P/N 3072351-All, 3073113-All, 3073497-All, or 3074103-All, installed, replacement of the LPT stage 1 disk with a serviceable disk, at next major periodic inspection or at next access to the LPT stage 1 nozzle assembly, but not to exceed 1,500 hours time-in-service since last inspection, or before December 31, 2011, or at disk life limit, whichever occurs first.
• As optional terminating action to the repetitive actions of the proposed AD, replacement of the LPT stage 1 disk with a serviceable disk.
• For the purposes of this proposed AD, a serviceable LPT stage 1 disk is a disk having a part number not listed in this proposed AD.

The proposed AD would require you to use the service information described previously to perform these actions.

Costs of Compliance

There are about 5,462 TFE731-2 and -3 series turbofan engines of the affected design in the worldwide fleet. We estimate that 3,572 engines installed on airplanes of U.S. registry would be affected by this proposed AD. We also estimate that it would take about 8 work hours per engine to perform the proposed measurements and calculations during MPI, and about 2 work hours per engine to replace the disk during MPI. The average labor rate is $65 per work hour. Required replacement parts would cost about $30,000 per engine. We expect about 1,900 engines to have the LPT stage 1 disk replaced. Based on these figures, we estimate the total cost of the proposed AD to U.S. operators to be $58,151,000.

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 at the address listed under ADDRESSES.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

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.