AD 2008-01-03

This AD becomes effective February 14, 2008.

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

Steve Litke, Aerospace Engineer, Airframe and Services Branch, ACE-118W, FAA, Wichita Aircraft Certification Office, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas 67209; telephone (316) 946-4127; fax (316) 946-4107.

The FAA issued a supplemental notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that would apply to certain Learjet Model 45 airplanes. That supplemental NPRM was published in the Federal Register on June 18, 2007 (72 FR 33415). That supplemental NPRM proposed to require revising the Airworthiness Limitations section (ALS) of the airplane maintenance manual to incorporate certain inspections and compliance times to detect fatigue cracking of certain principal structural elements (PSEs).

We provided the public the opportunity to participate in the development of this AD. We have considered the single comment received.

Averitt Air states that the supplemental NPRM lists Chapter 4 of the Learjet 45 Maintenance Manual, Revision 38, dated April 24, 2006, as a means of compliance with the supplemental NPRM. Averitt points out that the maintenance manual is currently at Revision 39, with Revision 40 coming soon. Averitt states that as the supplemental NPRM is currently worded, with each revision to the maintenance manual the operator will have to review Chapter 4 of the maintenance manual to ensure no changes have been made. Averitt also points out that each operator is required by Federal Aviation Regulations (FARs) to comply with the latest revision of the airworthiness limitations for his aircraft. Averitt questions the issuance of the AD at this time. Averitt states that the manufacturer of Learjet Model 45 airplanes is proactive in advising the operator of revisions to the maintenance manual.

We infer that Averitt would like us to put words in the AD that allow for the use of later revisions of the maintenance manual. As Averitt notes, operators must comply with the terms of the ALS, as specified in sections 43.16 (for persons maintaining products) and 91.403 (for operators) of the Federal Aviation Regulations (14 CFR 43.16 and 14 CFR 91.403). However, for the FAA to require compliance with any new or more restrictive life limits and inspections that the manufacturer or the FAA might impose in the ALS, we must engage in rulemaking; if we do not engage in rulemaking, the revised limitations in the maintenance manual cannot be made mandatory. We do, however, agree with Averitt's request to allow accomplishing the AWL revision in accordance with later revisions. We have revised paragraph (f) of this AD to allow later revisions of the maintenance manuals as acceptable methods of compliance if they are approved by the Manager, Wichita Aircraft Certification Office (ACO), FAA.

We reviewed the relevant data, considered the comment received, and determined that air safety and the public interest require adopting the AD with the change described previously. We also determined that this change will not increase the economic burden on any operator or increase the scope of the AD.

There are about 347 airplanes of the affected design in the worldwide fleet. This AD affects about 258 airplanes of U.S. registry. The actions take about 1 work hour per airplane, at an average labor rate of $80 per work hour. Based on these figures, the estimated cost of this AD for U.S. operators is $20,640, or $80 per airplane.

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.

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 this AD:

(1) Is not a “significant regulatory action” under Executive Order 12866;

(2) Is not a “significant rule” under 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.

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows:

1. The authority citation for part 39 continues to read as follows:

2. The Federal Aviation Administration (FAA) amends § 39.13 by adding the following new airworthiness directive (AD):