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-31/35 Heater Fuel Manual Shut-Off Valve - Removal 2/75 Applicability: Models PA-31 and PA-31-300 with S/Nos. 31-2 to 31-7401258. Document: Piper SB No. 417. Compliance: Within 100 hours time in service after 28 February 1975.