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-N22/62 Amdt 1 Stub Fin 12/90 DM Applicability: All Nomad N22 and N24 Aircraft. Requirement: Action in accordance with Nomad Alert SB ANMD-53-12 Rev.1. Compliance: 1. For aircraft that have not complied with SB NMD-53-5 or have not incorporated modification N600A or N600B - Prior to exceeding 25 hours time in service after 26 September 1990, and thereafter at periods not exceeding 100 hours time in service. 2. For aircraft that have complied with SB NMD-53-5 or have incorporated modification N600A or N600B - Prior to exceeding 100 hours time in service after 26 September 1990, and thereafter at periods not exceeding 100 hours time in service. 3. For aircraft that have incorporated modification N663 - Prior to exceeding 100 hours time in service after 26 September 1990. Note: Deformed or cracked parts shall be repaired or replaced before further flight. Background: A number of defects have been found involving the right hand stub fin spar cap, caused by horizontal stabiliser impact upon the lower stop. Defects in this area will cause a reduction in strength, and ability to carry design loads. Aircraft incorporating SB NMD 53-5 (mod N600A & B) have increased strength in the area and allow later initial compliance. Aircraft with modification N663 incorporated require one off inspection only. Amendment 1 references revised Requirement document, this relaxes the allowable damage limits and provides repair instructions.