Airworthiness directives: Learjet,

[Federal Register: June 26, 2006 (Volume 71, Number 122)]

[Proposed Rules]

[Page 36255-36257]

From the Federal Register Online via GPO Access [wais.access.gpo.gov]

[DOCID:fr26jn06-22]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-25174; Directorate Identifier 2005-NM-007-AD]

RIN 2120-AA64

Airworthiness Directives; Learjet Model 45 Airplanes

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

ACTION: Notice of proposed rulemaking (NPRM).

SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) for certain Learjet Model 45 airplanes. This proposed AD would require 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 proposed AD results from new and more restrictive life limits and inspection intervals for certain PSEs. We are proposing 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: We must receive comments on this proposed AD by August 10, 2006.

ADDRESSES: Use one of the following addresses to submit comments on this proposed 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 the service information identified in this proposed AD.

FOR FURTHER INFORMATION CONTACT: Steve Litke, Aerospace Engineer, Airframe 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.

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to submit any relevant written data, views, or arguments regarding this proposed AD. Send your comments to an address listed in the ADDRESSES section. Include the docket number ``FAA-2006- 25174; Directorate Identifier 2005-NM-007-AD'' at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments received by the closing date and may amend the proposed AD in light of those comments.

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 proposed 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 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

[[Page 36256]]

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.

Discussion

As service experience is accumulated on airplanes or as the result of post-certification testing and evaluation, it may become necessary to revise removal limits for removal of certain life-limited components of the airplane or revise the interval for certain structural inspections in order to ensure the continued structural integrity of the airplane. The manufacturer may revise the Airworthiness Limitations document to include more restrictive life limits or revise repetitive intervals for certain non-destructive inspection (NDI) techniques and procedures for each principal structural element (PSE). For the purposes of this airworthiness directive, a PSE is defined as an element of structure that contributes significantly to carrying flight, ground, and pressurization loads. If a failure occurs on any of those PSEs, it could adversely affect the structural integrity of the airplane.

The actions specified by the proposed AD are intended to ensure that fatigue cracking of various PSEs is detected and corrected; such fatigue cracking could adversely affect the structural integrity of these airplanes.

New Revisions of Airworthiness Limitations Sections (ALS)

We have reviewed Chapter 4, ``Airworthiness Limitations,'' of the Learjet 40 Maintenance Manual (MM), Revision 6, dated April 24, 2006; and Chapter 4, ``Airworthiness Limitations,'' of the Learjet 45 MM, Revision 38, dated April 24, 2006. These MM chapters add new and more restrictive life limits and inspection intervals for certain PSEs. PSEs include, but are not limited to, door cutouts, windshields, skin sections, bolts, and attachment hardware. The MM chapters explicitly identify all of the PSEs that are to be inspected in accordance with the requirements of the Airworthiness Limitations section (ALS). Accomplishing the actions specified in these chapters is intended to adequately address the unsafe condition.

FAA's Determination and Requirements of the Proposed AD

We have evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other airplanes of this same type design. For this reason, we are proposing this AD, which would require revising the ALS of the MM to incorporate certain inspections and compliance times to detect fatigue cracking of certain PSEs.

Clarification of Model Designations

Certain Learjet Model 45 airplanes are also referred to as Model 45 (Learjet 40) airplanes. Model 45 (Learjet 40) airplanes have serial numbers (S/Ns) 45-2001 through 45-4000 inclusive. The remainder of the Learjet Model 45 airplanes are referred to as Model 45 (Learjet 45) airplanes, and have S/Ns 45-002 through 45-2000 inclusive.

Costs of Compliance

There are about 230 airplanes of the affected design in the worldwide fleet. This proposed AD would affect about 171 airplanes of U.S. registry. The proposed actions would 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 the proposed AD for U.S. operators is $13,680, 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 proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would 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 proposed 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 proposed 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.

   The Proposed Amendment

   Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 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):

   Learjet: Docket No. FAA-2006-25174; Directorate Identifier 2005-NM- 007-AD.

   Comments Due Date

   (a) The FAA must receive comments on this AD action by August 10, 2006.

   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 45-233 inclusive, and S/Ns 45-2001 through 45-2031 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.

   [[Page 36257]]

   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.

   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 in paragraph (f)(1) or (f)(2) of this AD in the AMM is one approved method for doing the revision. Thereafter, except as provided in paragraph (g) of this AD, no alternative life limits or inspection intervals may be approved for the affected PSEs.

   (1) For Learjet Model 45 airplanes, S/Ns 45-002 through 45-233 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 45-2031 inclusive: Chapter 4 of the Learjet 40 Maintenance Manual, Revision 6, dated April 24, 2006.

   AMOCs

   (g)(1) The Manager, Wichita 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) Before using any AMOC approved in accordance with Sec. 39.19 on any airplane to which the AMOC applies, notify the appropriate principal inspector in the FAA Flight Standards Certificate Holding District Office.

   Issued in Renton, Washington, on June 14, 2006. Kalene C. Yanamura, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. E6-10004 Filed 6-23-06; 8:45 am]

   BILLING CODE 4910-13-P