AD 2003-17-08

This amendment supersedes an existing airworthiness directive (AD), applicable to certain Learjet Model 45 airplanes, that currently requires repetitive application of grease to the rotating disk assembly of the nose landing gear (NLG) squat switch mechanism. This amendment requires replacement of the squat switch camrod of the NLG, which terminates the repetitive application; and also reduces the applicability of the existing AD. The actions specified by this AD are intended to prevent moisture contamination and subsequent formation of ice which could cause bending and damage of the squat switch assembly, driving the nose wheel to an uncommanded angle against the force of the steering system. This condition, if not corrected, could result in the airplane departing the runway at high speeds during landing. This action is intended to address the identified unsafe condition.

Final rule.

2003-17-08 Learjet: Amendment 39-13283. Docket 2002-NM-13-AD. Supersedes AD 2000-22-04, Amendment 39-11950.

Applicability: Model 45 airplanes, certificated in any category; serial numbers (S/N) 45-005 through 45-071 inclusive, that have been modified per Bombardier Service Bulletin 45-32-3; and S/Ns 45-072 through 45-114 inclusive.

Note 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been otherwise modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (c)(1) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition hasnot been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent moisture contamination and subsequent formation of ice which could cause bending and damage of the squat switch assembly of the nose landing gear (NLG), driving the nose wheel to an uncommanded angle against the force of the steering system, and consequently resulting in the airplane departing the runway at high speeds during landing, accomplish the following:

Restatement of Requirements of AD 2000-22-04, Amendment 39-11950

Application of Grease

(a) Within 30 days after December 6, 2000 (the effective date of AD 2000-22-04, amendment 39-11950): Apply grease to the rotating disk assembly of the squat switch mechanism of the nose wheel in accordance with Bombardier Service Information Letter SIL 32-016, dated March 30, 2000. Thereafter, repeat this application at intervals not to exceed 30 days untilthe replacement required by paragraph (b) of this AD is accomplished.

New Requirements of This AD

Terminating Action

(b) Within 300 flight hours or 12 months after the effective date of this AD, whichever occurs first: Replace the camrod of the squat switch assembly of the NLG with a new assembly in accordance with the Accomplishment Instructions of Bombardier Service Bulletin SB 45-32-8, Revision 2, dated March 14, 2001. Accomplishment of the camrod replacement terminates the requirements of this AD.

Alternative Methods of Compliance

(c)(1) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Wichita Aircraft Certification Office (ACO), FAA. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Wichita ACO.

(2) Alternative methods of compliance, approved previously in accordance with AD 2000-22-04, amendment 39-11950, are approved as alternative methods of compliance with this AD.

Note 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Wichita ACO.

Special Flight Permits

(d) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

Incorporation by Reference

(e) The actions shall be done in accordance with Bombardier Service Information Letter SIL 32-016, dated March 30, 2000; and Bombardier Service Bulletin SB 45-32-8, Revision 2, dated March 14, 2001; as applicable.

(1) The incorporation by reference of Bombardier Service Bulletin SB 45-32-8, Revision 2, dated March 14, 2001, is approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51.

(2) The incorporation by reference of Bombardier Service Information Letter SIL 32-016, dated March 30, 2000, was approved previously by the Director of the Federal Register as of December 6, 2000 (65 FR 65257, November 1, 2000).

(3) Copies may be obtained from Learjet, Inc., One Learjet Way, Wichita, Kansas 67209-2942. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Wichita Aircraft Certification Office, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

Effective Date

(f) This amendment becomes effective on September 24, 2003.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 2000-22-04, amendment 39-11950 (65 FR 65257, November 1, 2000), which is applicable to certain Learjet 45 series airplanes, was published in the Federal Register on May 29, 2003 (68 FR 31999). The action proposed to require repetitive application of grease to the rotating disk assembly of the nose landing gear (NLG) squat switch mechanism. The action also proposed to require replacement of the squat switch camrod of the NLG, which would terminate the repetitive application; and would reduce the applicability of the existing AD. That action was prompted by tests conducted by the manufacturer that indicated a potential unsafe condition exists involving damage or bending of the squat switch assembly of the NLG due to moisture contamination and subsequent formation of ice.

Comments

Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were submitted in response to the proposal or the FAA's determination of the cost to the public.

Conclusion

The FAA has determined that air safety and the public interest require the adoption of the rule as proposed.

Changes to 14 CFR Part 39/Effect on the AD

On July 10, 2002, the FAA issued a new version of 14 CFR part 39 (67 FR 47997, July 22, 2002), which governs the FAA's airworthiness directives system. The regulation now includes material that relates to altered products, special flight permits, and alternative methods of compliance (AMOCs). Because we have now included this material in part 39, only the office authorized to approve AMOCs is identified in each individual AD. However, for clarity and consistency in this final rule, we have retained the language of the NPRM regarding that material.

Change to Labor Rate Estimate

We have reviewed the figures we have used over the past several years to calculate AD coststo operators. To account for various inflationary costs in the airline industry, we find it necessary to increase the labor rate used in these calculations from $60 per work hour to $65 per work hour. The cost impact information, below, reflects this increase in the specified hourly labor rate.

Cost Impact

There are approximately 110 airplanes of U.S. registry that will be affected by this AD.

The actions that are currently required by AD 2000-22-04 take approximately 1 work hour per airplane to accomplish, at an average labor rate of $65 per work hour. Based on these figures, the cost impact of the previously required actions on U.S. operators is estimated to be $7,150, or $65 per airplane.

The new actions that are required by this new AD will take approximately 3 work hours per airplane to accomplish, at an average labor rate of $65 per work hour. Required parts will cost approximately $205 per airplane. Based on these figures, the cost impact of the new requirements of this AD on U.S. operators is estimated to be $44,000, or $400 per airplane.

The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions.

Regulatory Impact

The regulations adopted herein 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. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that this action (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. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of the Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations(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. Section 39.13 is amended by removing amendment 39-11950 (65 FR 65257, November 1, 2000), and by adding a new airworthiness directive (AD), amendment 39-13283, to read as follows: