AIRWORTHINESS DIRECTIVE
For the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/LJ60/1 and issues the following AD under subregulation 39.1 (1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.
Learjet 60 Series Aeroplanes
AD/LJ60/1
Amdt 1
Abnormal Brake Wear Condition 7/2004
Applicability: Model 60 aircraft, equipped with Aircraft Braking Systems (ABS) brake assembly part number 5003096-7.
Requirement: 1. Measure the brake wear dimension between the housing sub-assembly 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 5 March 1998.
- If the dimension is less than 0.344 inches (8.74 mm), thereafter, repeat the measurement.
b. If the dimension is equal to or greater than 0.344 inches (8.74 mm), thereafter, repeat the measurement.
c. If the dimension is equal to or greater than 0.359 inches (9.12 mm) and less than 0.464 inches (11.79 mm), perform a visual inspection to detect abnormal wear of the friction mix on the rotating discs, in accordance with the Requirement document.
(i) If the friction mix is not worn to the disc cores on either disc, thereafter, repeat the measurement.
(ii) If the friction mix is worn to the disc core on either disc, replace both rotating discs with new discs in accordance with the Requirement document. Thereafter, repeat the measurement.
d. If the dimension is greater than or equal to 0.464 inches (11.79 mm), replace the disc stack with a new disc stack, or overhaul it; in accordance with the Requirement document. Thereafter, repeat the measurement.
2. A used ABS part number 5003096-7 brake assembly shall not be installed on any aircraft, unless it has been inspected and applicable corrective actions have been performed in accordance with the requirements of this Directive.
Note: FAA AD 98-16-18 Amdt 39-10694 refers.
Learjet 60 Series Aeroplanes
AD/LJ60/1 Amdt 1 (continued)
Compliance: 1. For brakes which have accumulated more than 100 cycles since new, accomplish within 10 flight hours after the effective date of this AD, unless the initial check is already accomplished. No inspection is required for brakes with less than 100 cycles accumulated.
- At intervals not to exceed 35 flight cycles.
b. At intervals not to exceed 25 flight cycles.
c. (i). Repeat at intervals not to exceed 25 flight cycles.
(ii). Before further flight. Subsequent repeat inspections are to be carried out in accordance with an initial threshold and repeat interval appropriate for new brakes, i.e. begin again from part 1 of this AD
d. Before further flight. Subsequent repeat inspections are to be carried out in accordance with an initial threshold and repeat interval appropriate for new brakes, i.e. begin again from part 1 of this AD.
2. As of the effective date of this Directive.
This Amendment becomes effective on 8 July 2004.
Background: This AD was raised in response to the release of an FAA AD that was issued after reports of abnormal (uneven) brake wear.
This amendment changes the compliance to reflect the compliance allowed in FAA letter of dispensation to the Danish LDD. Refer to FAA letter of dispensation, LDD 2000-099-047, dated November 12, 1998.
David Villiers
Delegate of the Civil Aviation Safety Authority 26 May 2004
The above AD is notified in the Commonwealth of Australia Gazette on 16 June 2004.