[Federal Register Volume 70, Number 127 (Tuesday, July 5, 2005)]
[Proposed Rules]
[Pages 38625-38627]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-13134]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2005-21719; Directorate Identifier 2005-NE-19-AD]
RIN 2120-AA64


Airworthiness Directives; Hamilton Sundstrand Power Systems 
(formerly Sundstrand Power Systems) Auxiliary Power Units Models T-62T-
46C2, T-62T-46C2A, T-62T-46C3, T-62T-46C7, and T-62T-46C7A

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

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD). 
The new AD is for Hamilton Sundstrand Power Systems (formerly 
Sundstrand Power Systems) auxiliary power units (APUs) models T-62T-
46C2, T-62T-46C2A, T-62T-46C3, T-62T-46C7, and T-62T-46C7A, with 
compressor impeller assembly, part number (P/N) 4502020 or 4502020A, 
installed. This proposed AD would require removal from service of those 
compressor impeller assemblies at reduced service life limits. This 
proposed AD results from two reports of uncontained failures of 
compressor impeller assemblies. We are proposing this AD to prevent an 
uncontained APU failure and damage to the airplane.

DATES: We must receive any comments on this proposed AD by September 6, 
2005.

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

[[Page 38626]]


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 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-2005-21719; 
Directorate Identifier 2005-NE-19-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 
Docket Management System (DMS) Web site, anyone can find and read the 
comments in any of our dockets. The Web site includes 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 DMS 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 DMS receives them.

Discussion

    We received two reports of uncontained failures of compressor 
impeller assemblies installed in Hamilton Sundstrand Power Systems 
model T-62T-46C3 APUs. One report was of a compressor impeller failing 
in the field, at 17,680 cycles-since-new (CSN). The other report was of 
a compressor impeller failing at the manufacturer's site. Hamilton 
Sundstrand has determined that these failures were caused by low-cycle-
fatigue (LCF) cracking. The LCF cracking starts on the compressor 
impeller back face radius, and grows circumferentially to failure, over 
a high number of cycles. This condition, if not corrected, could result 
in uncontained APU failure and damage to the airplane.

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, for Hamilton 
Sundstrand Power Systems model T-62T APUs with compressor impeller 
assembly P/N 4502020 or 4502020A installed, would require:
     For APUs with compressor impeller assemblies that have 
12,000 or more CSN on the effective date of the proposed AD, removal 
from service before accumulating 500 additional cycles; and
     For APUs with compressor impeller assemblies that have 
fewer than 12,000 CSN on the effective date of the proposed AD, removal 
from service at or before accumulating 12,500 CSN.

Costs of Compliance

    There are about 50 Hamilton Sundstrand Power Systems model T-62T 
APUs of the affected design in the worldwide fleet. We estimate that 
eight APUs 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 to remove and install an APU, and that the average labor rate is 
$65 per work hour. A new or serviceable compressor impeller assembly, 
P/N 4502020 or 4502020A, may be installed provided it meets the cycles-
since-new criteria in the compliance section of this proposed AD. It 
would take about 55.5 hours to remove and replace affected compressor 
impeller assembly parts. New configuration replacement parts for each 
APU would cost approximately $36,587. Based on these figures, we 
estimate the total cost of the proposed AD to U.S. operators, to 
remove, upgrade, and install the APUs to be $325,716.

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.


Sec.  39.13  [Amended]

    2. The FAA amends Sec.  39.13 by adding the following new 
airworthiness directive:


[[Page 38627]]


Hamilton Sundstrand: Docket No. FAA-2005-21719; Directorate 
Identifier 2005-NE-19-AD.

Comments Due Date

    (a) The Federal Aviation Administration (FAA) must receive 
comments on this airworthiness directive (AD) action by September 6, 
2005.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Hamilton Sundstrand Power Systems 
(formerly Sundstrand Power Systems) auxiliary power units (APUs) 
models T-62T-46C2, T-62T-46C2A, T-62T-46C3, T-62T-46C7, and T-62T-
46C7A, with compressor impeller assembly, part number (P/N) 4502020 
or 4502020A installed. These APUs are installed on, but not limited 
to, BAE Systems AVRO 146, Fokker 50, Saab 2000, and Saab 340 
airplanes.

Unsafe Condition

    (d) This AD results from two reports of uncontained failures of 
compressor impeller assemblies. We are issuing this AD to prevent an 
uncontained APU failure and damage to the airplane.

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.
    (f) For APUs with compressor impeller assemblies that have 
12,000 or more cycles-since-new (CSN) accumulated on the effective 
date of this AD, remove compressor impeller assemblies from service 
before accumulating 500 additional cycles.
    (g) For APUs with compressor impeller assemblies that have fewer 
than 12,000 CSN on the effective date of this AD, remove compressor 
impeller assemblies from service at or before accumulating 12,500 
CSN.

Alternative Methods of Compliance

    (h) The Manager, Los Angeles Aircraft 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

    (i) Hamilton Sundstrand Service Bulletins No. 4500090-49-33, 
dated January 6, 2005, No. 4500482-49-33, dated January 6, 2005, No. 
4501578-49-22, dated January 13, 2005, No. 4501690-49-47, dated 
November 19, 2004, and No. 4501909-49-16, dated January 13, 2005, 
pertain to the subject of this AD.

    Issued in Burlington, Massachusetts, on June 28, 2005.
Diane S. Romanosky,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 05-13134 Filed 7-1-05; 8:45 am]
BILLING CODE 4910-13-P