COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Cessna 340 Series Aeroplanes AD/CESSNA 340/29 Seat Back Reinforcing Strap 4/93 Applicability: S/N 340-0001 to 340A1817. Requirement: Action in accordance with Cessna MEB 89-3. Compliance: Prior to 30 June 1993. Background: In Australia there is a history of seat back failure in the aircraft referred to in the MEB. The most recent being a total failure in IMC conditions, which in normal single pilot operation would have resulted in total loss of control near the ground.