COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Piper PA-25 (Pawnee) Series Aeroplanes AD/PA-25/37 Goodyear Fuel Cells - Inspection 6/78 Applicability: Models PA-25, PA-25-235 and PA-25-260 with S/Nos. 25-1 to 25-7405572, fitted with Goodyear BTC-39 fuel cells. Document: Piper SB No. 591. Compliance: Within 100 hours time in service after 30 June 1978 and thereafter annually as detailed in Piper SB No. 591.