Airworthiness Directives; Hamilton Sundstrand Power Systems T-62T Series Auxiliary Power Units (APUs)

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for Hamilton Sundstrand Power Systems Models T-62T-46C12 and T-62T-40C14 (APS 500R) APUs with fuel filter housing assembly, part numbers (P/Ns) 4951627, 4951960, or 4952039, installed. This proposed AD would require installation of a bracket to prevent a failed bypass button from protruding beyond the internal o-ring seal. This proposed AD results from reports of leaks caused by cracked bypass buttons that protruded beyond the o-ring seal. We are proposing this AD to prevent a fire or explosion caused by a fuel leak from a failed bypass button on the fuel filter housing.

DATES:

We must receive any comments on this proposed AD by July 6, 2004.

ADDRESSES:

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

• By mail: Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 2003-NE-61-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 Hamilton Sundstrand Technical Publications Department, P.O. Box 7002, Rockford, IL 61125-7002, U.S.A.

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

FOR FURTHER INFORMATION CONTACT:

Roger Pesuit, Aerospace Engineer, Los Angeles Aircraft Certification Office, FAA, Transport Airplane Directorate, 3960 Paramount Blvd., Lakewood, CA 90712-4137; telephone (562) 627-5251, fax (562) 627-5210.

SUPPLEMENTARY INFORMATION:

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 “AD Docket No. 2003-NE-61-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.

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 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 October 22, 2003, Hamilton Sundstrand Power Systems advised us that they received reports of five fuel filter housing assemblies on which the bypass buttons failed. Fuel filter housing assemblies, P/Ns 4951627, 4951960, and 4952039, have bypass buttons that can fail from fatigue cracks. When the bypass button cracks through, the indicating portion of the button can extend beyond the internal o-ring seal and can allow fuel to leak into the APU compartment. This condition, if not corrected, could result in a fire or explosion caused by a fuel leak from a failed bypass button on the fuel filter.

Relevant Service Information

We have reviewed and approved the technical contents of Hamilton Sundstrand Power Systems Alert Service Bulletin (ASB) No. ASB-4504112-49-22, dated December 2, 2003; and ASB No. ASB-4503067-49-9, dated December 2, 2003, that describe procedures for installing brackets on the fuel filter.

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 installing a bracket to prevent a failed bypass button from protruding beyond the internal o-ring seal.

Interim Action

These actions are interim actions and we may take further rulemaking actions in the future.

Costs of Compliance

There are about 552 Hamilton Sundstrand APUs of the affected design in the worldwide fleet. We estimate that 448 APUs installed on airplanes of U.S. registry would be affected by this proposed AD. We also estimate that it would take about 1 work hour per APU to perform the proposed actions, and that the average labor rate is $65 per work hour. Required parts would cost about $517 per APU. The manufacturer indicated that they might provide the parts at no cost. Based on these figures, we estimate the total cost of the proposed AD to U.S. operators to be $260,736.

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. 2003-NE-61-AD” in your request.

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.