AD 98-16-18 Airworthiness Directives; Learjet Model 60 Airplanes

Models named: 60. Read the applicability below — it usually turns on serial or part numbers too.

Model 60 airplanes equipped with Aircraft Braking Systems (ABS) brake assemblies having part number 5003096-7, 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 (c) 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.

Required as indicated, unless accomplished previously. To detect and repair an abnormal (uneven) brake wear condition, which could result in loss of brake effectiveness and cause the airplane to leave the runway surface, accomplish the following: (a) Within 10 flight hours after the effective date of this AD, measure the brake wear dimension between the housing subassembly and the pressure plate that is adjacent to the top pistons of the brake assembly, in accordance with ABS Service Bulletin LEAR60-32-03, dated March 5, 1998. (1) If the dimension is less than 0.359 inch (9.12 mm), thereafter repeat the measurement at intervals not to exceed 25 flight cycles. [[Page 42210]] (2) If the dimension is equal to or greater than 0.359 inch (9.12 mm) and less than 0.464 inch (11.79 mm), prior to further flight, perform a visual inspection to detect abnormal wear of the friction mix on the rotating disks, in accordance with the service bulletin. (i) If the friction mix is not worn to the disk cores on either disk, thereafter repeat the measurement at intervals not to exceed 25 flight cycles. (ii) If the friction mix is worn to the disk core on either disk, replace both rotating disks with new disks in accordance with the service bulletin. Thereafter, repeat the measurement at intervals not to exceed 25 flight cycles. (3) If the dimension is greater than or equal to 0.464 inch (11.769 mm), replace the disk stack with a new disk stack or overhaul it, in accordance with the service bulletin. Thereafter, repeat the measurement at intervals not to exceed 25 flight cycles. (b) As of the effective date of this AD, no person shall install on any airplane a used ABS brake assembly, part number 5003096-7, unless it has been inspected and applicable corrective actions have been performed in accordance with the requirements of this AD. (c) 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. (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. (e) The actions shall be done in accordance with Aircraft Braking Systems Corporation Service Bulletin LEAR60-32-03, dated March 5, 1998. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. 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 FAA, Small Airplane Directorate, 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. (f) This amendment becomes effective on August 24, 1998. Issued in Renton, Washington, on July 30, 1998. Darrell M. Pederson, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 98-20970 Filed 8-6-98; 8:45 am] BILLING CODE 4910-13-P