Airworthiness Directives; Learjet Model 31, 31A, 35, 35A, and 60 Airplanes

[Federal Register Volume 64, Number 167 (Monday, August 30, 1999)] [Proposed Rules] [Pages 47148-47149] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 99-22396]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-15-AD] RIN 2120-AA64

Airworthiness Directives; Learjet Model 31, 31A, 35, 35A, and 60 Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Learjet Model 31, 31A, 35, 35A, and 60 airplanes. This proposal would require a visual inspection of the spoiler actuators to determine the serial number of the spoiler actuators; and replacement of the spoiler actuators with new actuators, if necessary. This proposal is prompted by failure of a spoiler actuator piston rod during the first production flight of a Model 60 airplane due to an incomplete heat treatment process. The actions specified by the proposed AD are intended to prevent failure of the spoiler actuator, which could result in the spoiler panel floating and inducing an uncommanded roll of the airplane.

DATES: Comments must be received by October 14, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 99-NM-15-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal holidays. The service information referenced in the proposed rule may be obtained from Learjet, Inc., One Learjet Way, Wichita, Kansas 67209- 2942. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Small Airplane Directorate, Wichita Aircraft Certification Office, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas.

FOR FURTHER INFORMATION CONTACT: Shane Bertish, Aerospace Engineer, Systems and Equipment Branch, ACE-116W, FAA, Small Airplane Directorate, Wichita Aircraft Certification Office, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas 67209, telephone (316) 946-4156; fax (316) 946-4407.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this notice may be changed in light of the comments received. Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket. Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must submit a self-addressed, stamped postcard on which the following statement is made: ``Comments to Docket Number 99-NM-15-AD.'' The postcard will be date stamped and returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 99-NM-15-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA has received a report of failure of the spoiler actuator piston rod on the first production flight of a Learjet Model 60 airplane. Investigation revealed that a group of actuator piston rods had undergone an incomplete heat treating process that failed to achieve the desired material properties. This condition, if not corrected, could result in the spoiler panel floating and inducing an uncommanded roll of the airplane. The subject spoiler actuator piston rods on Learjet Model 31, 31A, 35, and 35A airplanes are identical to those on the affected Learjet Model 60 airplanes. Therefore, all of these airplanes may be subject to the same unsafe condition.

Explanation of Relevant Service Information

The FAA has reviewed and approved Learjet Service Bulletins SB 31- 27-19, dated December 14, 1998 (for Model 31 and 31A airplanes); SB 35- 27-36, dated December 14, 1998 (for Model 35 and 35A airplanes); and SB 60-27-21, dated December 14, 1998 (for Model 60 airplanes). These service bulletins describe procedures for a visual inspection of the spoiler actuators to determine the serial number of the spoiler actuators; and replacement of the spoiler actuators with new actuators, if necessary. Accomplishment of the actions specified in the service bulletins is intended to adequately address the identified unsafe condition.

Explanation of Requirements of Proposed Rule

Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would require accomplishment of the actions specified in the applicable service bulletin described previously.

Cost Impact

There are approximately 45 airplanes of the affected design in the worldwide fleet. The FAA estimates that 37 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 1 work hour per airplane to accomplish the proposed inspection, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the

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proposed AD on U.S. operators is estimated to be $2,220, or $60 per airplane. The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted.

Regulatory Impact

The regulations proposed herein would not have substantial direct effects 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, in accordance with Executive Order 12612, it is determined that this proposal would not have sufficient federalism implications to warrant the preparation of a Federalism Assessment. For the reasons discussed above, I certify that this 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) if promulgated, 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 copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend 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.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new airworthiness directive:

Learjet, Inc.: Docket 99-NM-15-AD.

Applicability: Model 31 and 31A airplanes, serial numbers 31- 033, 31-105, 31-114, 31-126, and 31-150 through 31-161 inclusive; Model 35 and 35A airplanes, serial numbers 35-065, 35-242, 35-300, 35-323, 35-447, 35-622, and 35-670; and Model 60 airplanes, serial numbers 60-029, 60-050, 60-120 through 60-139 inclusive; certificated in any category.

Note 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been 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 (b) 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 has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously. To prevent failure of the spoiler actuator, which could result in the spoiler panel floating and inducing an uncommanded roll of the airplane, accomplish the following:

Inspection and Replacement

(a) Within 150 flight hours after the effective date of this AD, perform a visual inspection to determine the serial number of the spoiler actuators, in accordance with Learjet Service Bulletins SB 31-27-19, dated December 14, 1998 (for Model 31 and 31A airplanes); SB 35-27-36, dated December 14, 1998 (for Model 35 and 35A airplanes); or SB 60-27-21, dated December 14, 1998 (for Model 60 airplanes); as applicable. (1) If the serial number is not listed in the applicable service bulletin, no further action is required by this AD. (2) If the serial number is listed in the applicable service bulletin, prior to further flight, replace the spoiler actuators with new actuators in accordance with the Accomplishment Instructions of the applicable service bulletin.

Alternative Methods of Compliance

(b) 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, Small Airplane Directorate. 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.

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

(c) 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.

Issued in Renton, Washington, on August 23, 1999. Vi L. Lipski, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 99-22396 Filed 8-27-99; 8:45 am] BILLING CODE 4910-13-P