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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. FAA-2007-27980; Directorate Identifier 2007-NM-066-AD; Amendment 39-15033; AD 2007-09-03] 
          - RIN 2120-AA64 

# AGENCY:

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

# ACTION:

Final rule; request for comments. 

# SUMMARY:

The FAA is adopting a new airworthiness directive (AD) for certain Learjet Model 45 airplanes. This AD requires deactivating the auxiliary power unit (APU), capping/plugging the fuel lines to the APU, and removing the APU fuel shutoff valve. This AD results from reports of fuel leaking from the APU fuel shutoff valve into a flammable fluid fire protection area that is also interconnected with the main landing gear's wheel well bay. We are issuing this AD to prevent fuel leaking from the fuel shutoff valve of the APU, which could result in an uncontrollable fire and adversely affect the airplane's continued safe flight and landing. 

# DATES:

This AD becomes effective May 11, 2007. 

                        The Director of the Federal Register approved the incorporation by reference                               ( print page 20717)                            of a certain publication listed in the AD as of May 11, 2007.                     

We must receive comments on this AD by June 25, 2007. 

# ADDRESSES:

Use one of the following addresses to submit comments on this 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.
      - 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.

Contact Learjet, Inc., One Learjet Way, Wichita, Kansas 67209-2942, for service information identified in this AD. 

# FOR FURTHER INFORMATION CONTACT:

James P. Galstad, Aerospace Engineer, Mechanical Systems and Propulsion Branch, ACE-116W, FAA, Wichita Aircraft Certification Office, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas 67209; telephone (316) 946-4135; fax (316) 946-4107. 

# SUPPLEMENTARY INFORMATION:

## Discussion 

We have received a report indicating that there have been 16 occurrences of fuel leaking from the fuel shutoff valve of the auxiliary power unit (APU), on Model 45 airplanes in the field and on the production line. Epoxy was used in the valve to seal or adhere certain components of the valve. The epoxy was found to have been improperly prepared and/or applied, which allowed fuel to leak out through and/or around the electrical switch and connector in the bottom of the valve. Some valves were also found to have internal leaks due to fuel-soaked silicone sealant that had expanded into the electrical switch's location. The APU's fuel shutoff valve leaks fuel into a flammable fluid fire protection area that is also interconnected with the main landing gear's wheel well bay. This condition, if not corrected, could result in an uncontrollable fire, which could adversely affect the airplane's continued safe flight and landing. 

## Relevant Service Information 

We have reviewed Bombardier Alert Service Bulletin A45-49-11, dated March 26, 2007. The service bulletin describes procedures for deactivating the APU, capping/plugging the fuel lines to the APU, and removing the APU fuel shutoff valve. Deactivating the APU also involves attaching inoperative APU placards in various locations. The service bulletin also describes procedures for sending the removed APU shutoff valves and compliance information to Learjet. 

## FAA's Determination and Requirements of This AD 

The unsafe condition described previously is likely to exist or develop on other airplanes of the same type design. For this reason, we are issuing this AD to prevent fuel leaking from the fuel shutoff valve of the APU, which could result in an uncontrolled fire and adversely affect the airplane's continued safe flight and landing. This AD requires accomplishing the actions specified in the service information described previously, except as discussed under “Differences Between the AD and the Service Bulletin.” 

## Differences Between the AD and the Service Bulletin 

Operators should note that, although the Accomplishment Instructions of the referenced service bulletin describe procedures for returning the APU's fuel shutoff valve to Learjet, this AD does not require that action. 

Operators should also note that, although the Accomplishment Instructions of the referenced service bulletin describe procedures for submitting a compliance response form for recording compliance with the service bulletin, this AD does not require that action. 

## Interim Action 

This AD is considered to be interim action. The manufacturer has advised us that it currently is developing a modification that will address the unsafe condition addressed by this AD. Once this modification is approved, we may consider additional rulemaking. 

## FAA's Determination of the Effective Date 

Since an unsafe condition exists that requires the immediate adoption of this AD, we have found that notice and opportunity for public comment before issuing this AD are impracticable, and that good cause exists to make this AD effective in less than 30 days. 

## Comments Invited 

                    This AD is a final rule that involves requirements that affect flight safety and was not preceded by notice and an opportunity for public comment; however, we invite you to submit any relevant written data, views, or arguments regarding this AD. Send your comments to an address listed in the                     **ADDRESSES**                     section. Include “Docket No. FAA-2007-27980; Directorate Identifier 2007-NM-066-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the AD that might suggest a need to modify it.                 

                    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 AD. Using the search function of that 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 Docket 

                    You may examine the AD docket on the Internet at                     *http://dms.dot.gov*, or in person at the Docket Management Facility office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Management Facility office (telephone (800) 647-5227) is located on the plaza level of the Nassif Building at the DOT street address stated in the                     **ADDRESSES**                     section. Comments will be available in the AD docket shortly after the Docket Management System receives them.                 

## 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                           ( print page 20718)                        products identified in this rulemaking action.                 

## Regulatory Findings 

We have determined that this AD will not have federalism implications under Executive Order 13132. This AD will 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 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. Will 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 AD and placed it in the AD docket. 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
      - Incorporation by reference
      - Safety

## Adoption of the Amendment 

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 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 Federal Aviation Administration (FAA) amends § 39.13 by adding the following new airworthiness directive (AD): 

**2007-09-03 LEARJET:**                             Amendment 39-15033. Docket No. FAA-2007-27980; Directorate Identifier 2007-NM-066-AD.                         

## Effective Date 

(a) This AD becomes effective May 11, 2007. 

## Affected ADs 

(b) None. 

## Applicability 

(c) This AD applies to Learjet Model 45 airplanes, certificated in any category; serial numbers 45-005 through 45-321, equipped with an auxiliary power unit (APU). 

## Unsafe Condition 

(d) This AD results from reports of fuel leaking from the APU fuel shutoff valve into a flammable fluid fire protection area that is also interconnected with the main landing gear's wheel well bay. We are issuing this AD to prevent fuel leaking from the fuel shutoff valve of the APU, which could result in an uncontrollable fire and adversely affect the airplane's continued safe flight and landing. 

## 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. 

## Deactivation of the APU and Removal of the APU Fuel Shutoff Valve 

(f) Within 50 flight hours after the effective date of this AD, deactivate the APU, cap/plug the fuel lines to the APU, and remove the APU fuel shutoff valve, in accordance with the Accomplishment Instructions of Bombardier Alert Service Bulletin A45-49-11, dated March 26, 2007. 

## Differences From the Service Information 

(g) Although Bombardier Alert Service Bulletin A45-49-11, dated March 26, 2007, specifies to submit certain information to the manufacturer and send the APU fuel shutoff valve to Learjet, this AD does not include those requirements. 

## Special Flight Permit 

(h) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished, provided the APU is not used. 

## Alternative Methods of Compliance (AMOCs) 

(i)(1) The Manager, Wichita Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19. 

(2) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Before using any approved AMOC on any airplane to which the AMOC applies, notify your appropriate principal inspector (PI) in the FAA Flight Standards District Office (FSDO), or lacking a PI, your local FSDO. 

## Material Incorporated by Reference 

                            (j) You must use Bombardier Alert Service Bulletin A45-49-11, dated March 26, 2007, to perform the actions that are required by this AD, unless the AD specifies otherwise. The Director of the Federal Register approved the incorporation by reference of this document in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Contact Learjet, Inc., One Learjet Way, Wichita, Kansas 67209-2942, for a copy of this service information. You may review copies at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to:                             *http://www.archives.gov/​federal-register/​cfr/​ibr-locations.html.*

Issued in Renton, Washington, on April 16, 2007. 

Ali Bahrami, 

Manager,  Transport Airplane Directorate, Aircraft Certification Service.

 [FR Doc. E7-7640 Filed 4-25-07; 8:45 am] 

BILLING CODE 4910-13-P