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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

# 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 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:                         *roger.pesuit@faa.gov*; 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,                           ( print 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.

§ 39.13

2. The FAA amends § 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:                                 *roger.pesuit@faa.gov*; 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