COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Gates Learjet 35 and 36 Series Aeroplanes AD/LEARJET 35/26 Forward Engine Mounts 5/87 DM Applicability: All models 35 and 36 series aircraft with S/Nos. 35-001 to 35-522 and 36-001 to 36- 053 which do not incorporate forward engine mounts P/N 2651034. Requirement: Inspect the forward engine mounts in accordance with Gates Learjet SB 35/36-71-3. Note 1: Aircraft known to have unrepaired cracks shall not be returned to service without the prior approval of the Secretary. Note 2: It is requested that inspections which result in no defects being discovered are reported to the Secretary, in order that the need for this requirement may be reviewed in the future. Note 3: FAA AD 86-02-06 refers. Compliance: (a) Visual Inspection - Part 2A of the SB: Prior to exceeding 2400 hours total time in service or within 75 hours time in service after 18 March 1987, whichever occurs later, and thereafter at intervals not exceeding 420 hours time in service. (b) Magnetic Particle Inspection - Part 2B of the SB: Prior to exceeding 2400 hours total time in service or within 1500 hours time in service after 18 March 1987, whichever occurs later, and thereafter at intervals not exceeding 1500 hours time in service. Background: The manufacturer has reported a case of cracking in both engine mounts on a Model 35 aircraft. Further testing revealed that one of the engine mounts would not sustain the required regulatory loads.