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 35/22 Aileron Trim Tab Balance Weight - Replacement Applicability: All model Learjet with serial numbers listed in Requirement Document. Requirement: Gates Learjet AMK 83-3. Note: FAA AD 84-19-06 refers. 12/84 Compliance: Within 600 hours time in service after 31 December 1984 or the next aileron/trim tab removal or rebalance whichever occurs first. Background: The manufacturer has determined that the aileron trim tab balance weight is insufficient to meet the failsafe design requirements. This modification is needed to prevent possible flutter in the event of a disconnect in the trim tab system.