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-30/31 Aileron Nose Rib - Inspection and Modification 11/79 Applicability: All models: PA-30 with S/Nos. 30-1 and up, and PA-39 with S/Nos. 39-1 and up. Document: 1. Piper SL NO. 850; or 2. FAA AD 79-20-10, Amdt. 39-3579. Compliance: Inspect within 100 hours time in service after 30 November 1979 and thereafter at intervals not exceeding 100 hours time in service until modified by fitting Piper Kit No. 763 893. Background: The manufacturer has received reports of cracks developing in the aileron nose rib of several aeroplanes regardless of any previous modification kit fitted.