COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Beechcraft 99 Series Aeroplanes AD/BEECH 99/4 Vertical Stabiliser Main Spar 6/95 Applicability: Beech 99, 99A, A99A and B99 aircraft, serial numbers U-1 to U-151. Requirement: Visually inspect, using a borescope, both flanges of the vertical stabiliser main spar and angle doubler as specified in Beech Service instruction (SI) 0530-134. Note: FAA AD 90-15-18 refers. Compliance: Initially inspect before 2000 hours' time in service or before 50 hours' time in service after 25 May 1995, whichever occurs last. Re-inspect at intervals not to exceed 500 hours' time in service. Installation of a doubler over uncracked structure in accordance with Beech SI 0530- 134, Fig 3; or stabiliser replacement with P/N 115-640000-605, -607 or -651 cancels the Requirement of this Directive. Background: Cracking has been experienced in the vertical stabiliser main spar.