COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Cessna 188 (Agwagon) Series Aeroplanes AD/CESSNA 188/36 Vertical Fin Rear Spar 12/80 Applicability: Model 188 with S/Nos. 18801375 to 18803725 and T18803307T to T18803725T. Requirement: Action in accordance with Cessna SIL No. SE80-85. Compliance: Within 100 hours time in service after 31 December 1980. Background: Overseas, cracks have been found in the flanges and web of the spar below the lower rudder hinge.