COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Piper PA-23 (Apache and Aztec) Series Aeroplanes AD/PA-23/73 Stabilator Tab Horn - Replacement 10/77 Applicability: All model PA23-250 (6 Place) Aztec "F" with S/Nos. 27-7654001 to 27-7754127, 27-7754130, 27-7754131, 27-7754133 to 27-7754136 and 27-7754138 to 27- 7754144. Document: Piper SB No. 569. Compliance: Within 100 hours time in service after 31 October 1977.