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-N22/63 Amdt 1 Stub Fin Plate P/N 1D/N-12-57 7/94 DM Applicability: All Nomad N22 and N24 series aircraft fitted with an aluminium alloy stub fin plate, P/N 1D/N-12-57. Requirement: Remove the stub fin plate and replace with a new steel plate P/N 1E/N-12-57, in accordance with ASTA Service Bulletin ANMD-53-13 Revision 2. Compliance: Replace before 500 hours time in service (TIS), or within 100 hours TIS from 27 April 1994, whichever occurs later. Background: Previous inspections discovered fatigue cracks along the forward flange of the aluminium alloy stub fin plate on a number of aircraft. Failure of this plate could result in a loss of stiffness in the stub fin, with consequent empennage control problems. Therefore, this amendment requires fitment of an improved plate made of steel that is expected to have a longer life than the alloy plate.