Discussion
We have received a report of a fire in the left-hand engine nacelle on a Learjet Model 45 airplane. Investigation revealed that an electrical wire bundle for the engine alternator had chafed a hole in a hydraulic line. This condition, if not corrected, could result in a fire in the engine nacelle.
Relevant Service Information
We have reviewed Bombardier Alert Service Bulletin SB A40-71-01, dated September 29, 2005 (for Learjet Model 45 airplanes with serial numbers (S/Ns) 45-2001 through 45-2029 inclusive); and Bombardier Alert Service Bulletin SB A45-71-4, dated September 29, 2005 (for Learjet Model 45 airplanes with S/Ns 45-005 through 45-273 inclusive). These service bulletins describe procedures for modifying the electrical wire bundle for the alternator on the left-hand engine to separate the wiring from the hydraulic pump lines and to protect the wiring; inspecting the left and right engines to make sure that the proper clearances are maintained between all wiring harnesses and engine tubing; and correcting improper clearances if necessary. The service bulletins also specify sending a compliance report to the manufacturer.
We have also reviewed Bombardier Service Bulletin SB 40-24-01, dated April 22, 2005 (for Learjet Model 45 airplanes with S/Ns 45-2001 through 45-2015 inclusive); and Bombardier Service Bulletin SB 45-24-6, dated April 22, 2005 (for Learjet Model 45 airplanes with serial numbers 45-005 through 45-254 inclusive). The actions in these service bulletins must be accomplished before or concurrently with Bombardier Alert Service Bulletins SB A40-71-01 and SB A45-71-4. Bombardier Service Bulletin SB 40-24-01 and SB 45-24-6 describe procedures for replacing the fuses for the hydraulic shutoff valves with fuses having higher amperage.
Accomplishing the actions specified in the service information is intended to adequately address the unsafe condition.
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 chafing between the wire bundle for the alternator on each engine and the hydraulic lines, which could result in a fire in the engine nacelle. This AD requires accomplishing the actions specified in the applicable service information described previously, except as discussed under "Difference Between the AD and Bombardier Alert Service Bulletins SB A40-71-01 and SB A45-71-4."
Difference Between the AD and Bombardier Alert Service Bulletins SB A40-71-01 and SB A45-71-4
Although Bombardier Alert Service Bulletins SB A40-71-01 and SB A45-71-4 specify sending a compliance report to the manufacturer, this AD does not include that requirement.
Clarification of Inspection Terminology
In this AD, the "inspecting for proper clearance" specified in Bombardier Alert Service Bulletins SB A40-71-01 and SB A45-71-4, is referred to as a "general visual inspection." We have included the definition for this inspection in a note in the AD.
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-2005- 23144; Directorate Identifier 2005-NM-218-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 Dockets
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 thatis 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):