Airworthiness Directives; Honeywell International Inc. TPE331 Series Turboprop, and TSE331-3U Model Turboshaft Engines

AGENCY:

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

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for certain Honeywell International Inc. TPE331 series turboprop, and TSE331-3U model turboshaft engines. This proposed AD would require implementing a new flight cycle counting method for first, second, and third-stage turbine rotors used in aircraft that make multiple takeoffs and landings without an engine shutdown, and removing turbine rotors from service that have reached or exceeded their cycle life limits. This new flight cycle counting method would require determining total equivalent cycles accrued. This proposed AD results from several reports of uncontained turbine rotor separation on engines used in special-use operations. We are proposing this AD to prevent uncontained failure of the turbine rotor due to low-cycle-fatigue (LCF), and damage to the aircraft.

DATES:

We must receive any comments on this proposed AD by April 24, 2006.

ADDRESSES:

Use one of the following addresses to comment 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, Systems & Services, Technical Data Distribution, M/S 2101-201, P.O. Box 52170, Phoenix, AZ 85072-2170; telephone: (602) 365-2493 (General Aviation); (602) 365-5535 (Commercial); fax: (602) 365-5577 (General Aviation and Commercial).

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:

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-2006-23704; Directorate Identifier 2006-NE-02-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 DOT 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.

Examining the AD Docket

You may examine the docket that contains the proposal, any comments received and, any final disposition in person at the DOT Docket Office 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 Docket Management Facility receives them.

Discussion

We received several reports of turbine rotor separations on Honeywell International Inc. TPE331 turboprop series engines, resulting in metal fragments either penetrating the engine case or exiting the tail pipe. These engines were in special-use operations that typically include minor cycles (aircraft that make multiple takeoffs and landings without an engine shutdown).

We found that as minor cycles on these engines accumulate, so does LCF damage to the turbine rotors, just like LCF damage does from a major cycle (engine start, takeoff, landing, shutdown). Further, the manufacturer's major life cycle calculations do not address special-use operations (aircraft that make multiple takeoffs and landings without an engine shutdown). Special-use operations typically include agricultural, skydiving, and certain cargo flight operations, where the number of minor cycles generally ranges between five and twenty takeoffs-and-landings (to ground idle) per major cycle.

This proposed AD is related to the recent FAA safety evaluation on Mitsubishi MU-2B series airplanes. This condition, if not corrected, could result in LCF damage to the turbine rotors, resulting in uncontained turbine rotor failure and damage to the aircraft.

Relevant Service Information

We have reviewed the technical contents of Honeywell International Inc. Alert Service Bulletins (ASBs) No. TPE331-A72-2111, dated November 12, 2002; No. TPE331-A72-2123, dated February 8, 2006; No. TPE331-A72-2130, dated September 27, 2005; and TPE331-A-72-2131, dated September 27, 2005, that describe procedures for determining total equivalent cycles (major cycles plus minor cycles) for first, second, and third-stage turbine rotors used in special-use operations and procedures for removing over-limit turbine rotors from service.

We have also reviewed and approved the technical contents of Honeywell International Inc. Service Bulletins (SBs) No. TPE331-72-0019, Revision 22, dated May 16, 2001; SB No. TPE331-72-0180, Revision 31, dated November 7, 2003; and SB No. TP331-72-0476, Revision 27, dated September 17, 2003, and AlliedSignal Inc. SB No. TP331-72-0117, Revision 11, dated November 13, 1997, that describe procedures for recording total equivalent cycles.

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

The proposed AD would allow special-use operators to remove over-limit turbine rotors either according to Table 1 of the removal schedule in the applicable ASBs, or within nine months after the effective date of the proposed AD, whichever occurs later. This would allow high-utilization agricultural operators more time to comply with the proposed AD within their spraying season.

Also, the compliance time stated in compliance paragraph 1.D. of the applicable Honeywell ASBs is different from the proposed AD. Also, although the Honeywell and AlliedSignal ASBs and SBs address only the TPE331 series, and TSE331-3U model engines in service, the applicability of the proposed AD includes all certified TPE331-1 through -12 series engines and TSE331-3U model engines. Also, the proposed AD provides actions for used rotors installed on or after the effective date of this AD.

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:

• Determining and recording the total equivalent cycles for turbine rotors currently installed in engines that were or are in special-use operations; and
• Removing from service, turbine rotors that were or are in special-use operations that have reached or exceeded their cycle life limits; and
• Using the new flight cycle counting method that counts major and minor cycles as accrued for all new turbine rotors.

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

Costs of Compliance

We estimate that this proposed AD would affect 200 TPE331 series turboprop, and TSE331-3U model turboshaft engines installed on airplanes and helicopters of U.S. registry. We also estimate that it would take about two work hours per engine to perform the proposed total equivalent cycles determination and recording. We also estimate that to perform a proposed turbine engine removal it would take 40 work hours per engine when done at an unscheduled turbine section inspection, and one work hour per engine when done at a scheduled engine turbine section inspection. We estimate the average labor rate to be $65 per work hour. Required parts would cost about $20,000 per engine. The costs associated with this proposed AD are dependent on the engine mission cycle. Operators accruing many minor and major cycles might replace first and second stage turbine rotors every two years. For the purpose of this proposed AD, we estimate the costs for an eight-year period with moderate usage to be 10 minor cycles each flight and 200 flights each year, and the effective use of the first and second turbine rotors to be equivalent to 2,600 cycles. Based on these figures, we estimate the total cost to U.S. operators to be $9,350,630.

This is one of several actions that FAA is evaluating for unsafe conditions on the MU-2B airplanes. We estimate that 10 percent of the affected engines are used on MU-2B airplanes. To date, we have proposed the following actions:

Total proposed cost impact to date (including this NPRM) for the affected airplanes is $47,113 per airplane. This does not account for the following:

• The cost of any repairs or replacements based upon the results of inspections by the proposed actions; and
• The loss of revenue due to the airplane being down for work associated with any proposed AD action.

The total cost to date on all U.S. operators (including this NPRM) would be $18,703,940. This is based on the presumption that 10 airplanes would need the actions performed as specified by Docket No. FAA-2006-23704.

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 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

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.