COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Piper PA-31 Series Aeroplanes AD/PA-31/73 Elevator Cable - Inspection and Modification 12/78 Applicability: All models PA-31-350 with S/Nos 31-5001 to 31-7852151. Document: Piper SB No. 621. Compliance: Within the next 25 hours time in service after 15 November 1978.