COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES GAF N22 and N24 Series Aeroplanes AD/GAF-N22/36 Horizontal Stabiliser - Modification 4/80 Applicability: All models N22, N22B, N24 and N24A with S/Nos. referenced in SB No. NMD-55-10. Document: GAF SB No. NMD-55-10. Compliance: Before 1 August 1980. Background: In several cases the horizontal stabiliser has developed loose rivets, skin cracking and internal structural cracking during service.