COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Piper PA-30 & 39 (Twin Comanche) Series Aeroplanes AD/PA-30/33 Wing Main Spar Lower Cap - Inspection 9/83 Applicability: All model PA-30 with S/Nos. 30-2 to 30-2000. All model PA-39 with S/No. 39-1 to 39-155. Document: Piper Service Bulletin No. 751. Compliance: Within 100 hours time in service after 30th September 1983. Background: The Manufacturer reports cases of chafing of the wing main spar lower cap where the spar enters the fuselage.