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[Federal Register Volume 74, Number 69 (Monday, April 13, 2009)]
[Proposed Rules]
[Pages 16811-16812]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E9-8311]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2009-0247; Directorate Identifier 2009-NE-07-AD]
RIN 2120-AA64

Airworthiness Directives; Hamilton Sundstrand Power Systems T-
62T-46C12 Auxiliary Power Units

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for Hamilton Sundstrand Power Systems T-62T-46C12 auxiliary power units 
(APUs). This proposed AD would require upgrading the software in the 
APU full-authority digital controller (FADEC), from software version 
02.01.000 to version 03.00.000. This proposed AD results from two 
reports of APU compartment explosions due to over-fueling of the APU at 
low rpm during the start sequence. We are proposing this AD to prevent 
over-fueling of the APU during the start sequence, which could lead to 
fuel explosions, injury, and damage to the APU and the airplane.

DATES: We must receive any comments on this proposed AD by June 12, 
2009.

ADDRESSES: Use one of the following addresses to comment on this 
proposed AD.
     Federal eRulemaking Portal: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
     Mail: Docket Management Facility, U.S. Department of 
Transportation, 1200 New Jersey Avenue, SE., West Building Ground 
Floor, Room W12-140, Washington, DC 20590-0001.
     Hand Delivery: Deliver to Mail address above between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
     Fax: (202) 493-2251.

FOR FURTHER INFORMATION CONTACT: Roger Pesuit, Aerospace Engineer, Los 
Angeles Aircraft Certification Office, FAA, Transport Airplane 
Directorate, 3960 Paramount Blvd., Lakewood, CA 90712; e-mail: 
[email protected]; telephone (562) 627-5251, fax (562) 627-5210.
    Contact Hamilton Sundstrand Technical Publications, One Hamilton 
Road, Mail Stop: 1A-3-Z63, Windsor Locks, CT 06096-1010; telephone 
(860) 654-3575, for a copy of the service information identified in 
this proposed AD.

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-2009-0247; Directorate 
Identifier 2009-NE-07-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://www.regulations.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 Web site, anyone can find and read the comments in any 
of our dockets, including, if provided, 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).

Examining the AD Docket

    You may examine the AD docket on the Internet at http://www.regulations.gov; or in person at the Docket Operations office 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The AD docket contains this proposed AD, the regulatory 
evaluation, any comments received, and other information. The street 
address for the Docket Operations office (telephone (800) 647-5527) is 
the same as the Mail address provided in the ADDRESSES section. 
Comments will be available in the AD docket shortly after receipt.

Discussion

    We received two reports of APU compartment explosions of Hamilton 
Sundstrand Power Systems T-62T-46C12 APUs, related to attempted start 
of the APU. In both events, the APU compartment was damaged, and the 
compartment doors were blown off the airplane. The APUs are ground 
operational only, and the airplanes were parked at the time of 
explosion. Investigation has revealed that the APU could receive an 
excessively rich fuel mixture at low rpm during the start sequence, due 
to the APU FADEC version 02.01.000 software, that can allow over-
fueling of the APU during starting. This condition, if not corrected, 
could result in over-fueling of the APU during the start sequence, 
which could lead to fuel explosion, injury, and damage to the APU and 
the airplane.

Relevant Service Information

    We have reviewed and approved the technical contents of Hamilton 
Sundstrand Power Systems Service Bulletin No. 4503067-49-12, Revision 
1, dated December 23, 2008, that describes procedures for upgrading the 
APU FADEC software to version 03.00.000. This upgrade eliminates the 
potential for over-fueling the APU during the start sequence.

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 
upgrading the APU FADEC software to version 03.00.000. 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 59 Hamilton 
Sundstrand Power Systems T-62T-46C12 APUs installed on airplanes of 
U.S. registry. We also estimate that it would take about three work-
hours per APU to perform the proposed actions, and that the average 
labor rate is $80 per work-hour. There is no required part cost. Based 
on these figures, we estimate the total cost of the proposed AD to U.S. 
operators to be $14,160.

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,

[[Page 16812]]

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 AD:
    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. 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, Incorporation by 
reference, 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:
Hamilton Sundstrand Power Systems: Docket No. FAA-2009-0247; 
Directorate Identifier 2009-NE-07-AD.

Comments Due Date

    (a) The Federal Aviation Administration (FAA) must receive 
comments on this airworthiness directive (AD) action by June 12, 
2009.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Hamilton Sundstrand Power Systems T-62T-
46C12 auxiliary power units (APUs). These APUs are installed on, but 
not limited to, Bombardier Inc. DHC-8-400 series airplanes.

Unsafe Condition

    (d) This AD results from two reports of APU compartment 
explosions due to over-fueling of the APU at low rpm during the 
start sequence. We are issuing this AD to prevent over-fueling of 
the APU during the start sequence, which could lead to fuel 
explosion, injury, and damage to the APU and 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.

Software Upgrade of the APU Full-Authority Digital Electronic 
Controller (FADEC)

    (f) At the next FADEC removal, but no later than 18 months after 
the effective date of this AD, upgrade the software in the APU FADEC 
from software version 02.01.000 to version 03.00.000, and change the 
FADEC part number (P/N) from 4503069E to 4503069F.
    (g) Use paragraphs 3.A through 3.F.(2) of the Accomplishment 
Instructions of Hamilton Sundstrand Power Systems Service Bulletin 
No. 4503067-49-12, Revision 1, dated December 23, 2008, to do the 
software upgrade and the FADEC P/N change.

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) Contact Roger Pesuit, Aerospace Engineer, Los Angeles 
Aircraft Certification Office, FAA, Transport Airplane Directorate, 
3960 Paramount Blvd., Lakewood, CA 90712; e-mail: 
[email protected]; telephone (562) 627-5251, fax (562) 627-5210, 
for more information about this AD.
    (j) Contact Hamilton Sundstrand Technical Publications, One 
Hamilton Road, Mail Stop: 1A-3-Z63, Windsor Locks, CT 06096-1010; 
telephone (860) 654-3575, for a copy of the service information 
referenced in this AD.

    Issued in Burlington, Massachusetts, on April 7, 2009.
Peter A. White,
Assistant Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. E9-8311 Filed 4-10-09; 8:45 am]
BILLING CODE 4910-13-P
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