Airworthiness Directives; Aerospace Technologies of Australia Pty Ltd. (Formerly Government Aircraft Factory) Models N22B, N24A, and N22S Airplanes

This amendment adopts a new airworthiness directive (AD) that applies to Aerospace Technologies of Australia Pty Ltd. (ASTA) Models N22B, N24A, and N22S airplanes that are not equipped with a part number (P/N) 1E/N-12-57 fuselage stub fin plate (MOD N759). This action requires replacing the existing fuselage stub fin plate with one of improved design, P/N 1E/N-12-57. This action results from several reports of cracks along the forward flange of the fuselage stub fin plate in the area of Rib Water Line (WL) 138.87. The actions specified by this AD are intended to prevent structural failure of the fuselage area caused by a cracked stub fin plate, which could result in loss of control of the airplane.