E8-163. Airworthiness Directives; Learjet Model 45 Airplanes

AGENCY:

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

ACTION:

Final rule.

SUMMARY:

The FAA is adopting a new airworthiness directive (AD) for certain Learjet Model 45 airplanes. This AD requires revising the Airworthiness Limitations section of the airplane maintenance manual to incorporate certain inspections and compliance times to detect fatigue cracking of certain principal structural elements (PSEs). This AD results from new and more restrictive life limits and inspection intervals for certain PSEs. We are issuing this AD to ensure that fatigue cracking of various PSEs is detected and corrected; such fatigue cracking could adversely affect the structural integrity of these airplanes.

DATES:

This AD becomes effective February 14, 2008.

ADDRESSES:

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

Examining the AD Docket

You may examine the AD docket on the Internet at http://www.regulations.gov;​; or in person at the Docket Management Facility between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this AD, the regulatory evaluation, any comments received, and other information. The address for the Docket Office (telephone [phone]) is the Document Management Facility, U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT:

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 [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Discussion

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).

Comments

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

Request To Clarify Paragraph (f) of the Supplemental NPRM

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.

Conclusion

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.

Costs of Compliance

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.

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 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.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• 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

[Amended]

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

2008-01-03 Learjet: Amendment 39-15328. Docket No. FAA-2006-25174; Directorate Identifier 2005-NM-007-AD.

Effective Date

(a) This AD becomes effective February 14, 2008.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Learjet Model 45 airplanes, certificated in any category; serial numbers (S/Ns) 45-002 through 45-302 inclusive, and S/Ns 45-2001 through 45-2049 inclusive.

Unsafe Condition

(d) This AD results from new and more restrictive life limits and inspection intervals for certain principal structural elements (PSEs). We are issuing this AD to ensure that fatigue cracking of various PSEs is detected and corrected; such fatigue cracking could adversely affect the structural integrity of these airplanes.

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.

Note 1:

This AD requires revisions to certain operator maintenance documents to include new inspections. Compliance with these inspections is required by 14 CFR 91.403(c). For airplanes that have been previously modified, altered, or repaired in the areas addressed by these inspections, the operator may not be able to accomplish the inspections described in the revisions. In this situation, to comply with 14 CFR 91.403(c), the operator must request approval for an alternative method of compliance (AMOC) according to paragraph (g) of this AD. The request should include a description of changes to the required inspections that will ensure the continued damage tolerance of the affected structure. The FAA has provided guidance for this determination in Advisory Circular (AC) 25.1529-1.

Revise the Airworthiness Limitations Section (ALS)

(f) Within 30 days after the effective date of this AD, revise the ALS of the airplane maintenance manual (AMM) to include new life limits and inspection intervals according to a method approved by the Manager, Wichita Aircraft Certification Office (ACO), FAA. Incorporating the applicable chapters specified in paragraph (f)(1) or (f)(2) of this AD in the AMM is one approved method for doing the revision. Accomplishing the revision in accordance with a later approved revision of the applicable maintenance manual is an acceptable method of compliance if the revision is approved by the Manager, Wichita ACO, FAA. Thereafter, no alternative life limits or inspection intervals may be used for the affected PSEs, unless the limit or interval is part of a later approved AMM revision or the limit or interval is approved as an alternative method of compliance (AMOC) in accordance with the procedures specified in paragraph (g) of this AD.

(1) For Learjet Model 45 airplanes, S/Ns 45-002 through 45-302 inclusive: Chapter 4 of the Learjet 45 Maintenance Manual, Revision 38, dated April 24, 2006.

(2) For Learjet Model 45 airplanes, S/Ns 45-2001 through 45-2049 inclusive: Chapter 4 of the Learjet 40 Maintenance Manual, Revision 6, dated April 24, 2006.

Note 2:

After an operator complies with the requirements of paragraph (f) of this AD, that paragraph does not require that operators subsequently record accomplishment of those requirements each time an action is accomplished according to that operator's FAA-approved maintenance inspection program.

AMOCs

(g)(1) The Manager, Wichita ACO, 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

(h) None.

Issued in Renton, Washington, on December 21, 2007.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.