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-31/54 Turbine Tailpipe Coupling - Replacement 3/77 Applicability: Model PA-31P with S/Nos 31P-1 to 31P-7730003. Document: Piper SB No. 534. Compliance: Within 100 hours time in service after 31 March 1977.