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 adoptionof 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 withFAA 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 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.
Sec. 39.13 [Amended]
2. The Federal Aviation Administration (FAA) amends Sec. 39.13 by adding the following new airworthiness directive (AD):