[Federal Register Volume 61, Number 105 (Thursday, May 30, 1996)] [Proposed Rules] [Pages 27030-27031] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 96-13498] ----------------------------------------------------------------------- DEPARTMENT OF TRANSPORTATION 14 CFR Part 39 [Docket No. 95-NM-240-AD] RIN 2120-AA64 Airworthiness Directives; Learjet Model 60 Airplanes AGENCY: Federal Aviation Administration, DOT. ACTION: Notice of proposed rulemaking (NPRM). ----------------------------------------------------------------------- SUMMARY: This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Learjet Model 60 airplanes. This proposal would require modification of the aft core cowl nozzle of the engine nacelles. This proposal is prompted by a report that the sealant material in the aft core cowl nozzle of the engine nacelle was found to extend higher than the nozzle's forward flange, which can allow it to interfere with the proper operation of the emergency fuel shutoff actuating mechanism. The actions specified by the proposed AD are intended to prevent physical interference of the emergency fuel shutoff actuating mechanism and resultant engine shutdown. DATES: Comments must be received by July 8, 1996. ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 95-NM-240-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: Jeffrey Janusz, Aerospace Engineer, Systems and Propulsion Branch, ACE-116W, FAA, Small Airplane Directorate, Wichita Aircraft Certification Office, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas 67209; telephone (316) 946-4148; 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 95-NM-240-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-103, Attention: Rules Docket No. 95-NM-240-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Discussion - The FAA has received a report that, during installation of the aft core cowl nozzle of the engine nacelle on a Learjet Model 60 airplane, the sealant material in the aft core cowl nozzle was found to be improperly extended higher than the nozzle's forward flange. The cause has been attributed to the apparent improper installation of the sealant material during production. Sealant material in the aft core cowl nozzle that extends too high, if not corrected, could interfere with proper operation of the lever of the emergency fuel shutoff actuating mechanism. Such interference could result in the failure of the emergency fuel shutoff actuating mechanism and resultant engine shutdown. - The FAA has reviewed and approved Learjet Service Bulletin SB 60- 71-2, dated May 12, 1995, which describes procedures for modification of the aft core cowl nozzle of the engine nacelles. Among other actions, the modification involves replacing the sealant on the aft core cowl nozzle with a filler made from 6061 aluminum, and reidentifying the aft core cowl nozzle. The modification will ensure that the sealant does not interfere with the function of the emergency fuel shutoff actuating mechanism. - 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 modification of the aft core cowl nozzle of the engine nacelles. The actions would be required to be accomplished in accordance with the service bulletin described previously. - There are approximately 39 Learjet Model 60 airplanes of the affected design in the worldwide fleet. The FAA estimates that 26 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 44 work hours per airplane to accomplish the proposed actions, and that the average labor rate is $60 per work hour. Required parts would be supplied by the manufacturer at no cost to the operators. Based on these figures, the cost impact of the proposed AD on U.S. operators is estimated to be $68,640, or $2,640 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. - 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 [[Page 27031]] 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: Docket 95-NM-240-AD. -Applicability: Model 60 airplanes, as listed in Learjet Service Bulletin SB 60-71-2, dated May 12, 1995; certificated in any category. -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 (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 the sealant material in the aft core cowl nozzle of the engine nacelles from interfering with the lever of the emergency fuel shutoff actuating mechanism, which could result in the failure of the emergency fuel shutoff actuating mechanism and resultant engine shutdown, accomplish the following: - (a) Within 90 days after the effective date of this AD, modify the aft core cowl nozzle of the engine nacelles in accordance with Learjet Service Bulletin SB 60-71-2, dated May 12, 1995. - (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. -(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 May 22, 1996. John J. Hickey, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 96-13498 Filed 5-29-96; 8:45 am] BILLING CODE 4910-13-U