COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Fokker F28 Series Aeroplanes AD/F28/78 Lap Joint at Stringer 16/17 and 58/59 11/96 Applicability: Models F28 Mk. 1000 through to 4000 Series, S/Nos. 11017 to 11241 that do not have SB F28/53-121 incorporated. Requirement: Action in accordance with Fokker SB F28/53-144. Note: RLD AD 1996-081(A) refers. Compliance: Unless already accomplished; on aircraft that have accumulated between: 1. 25 000 and 32 000 flight cycles at 01 July 1996 - before 10 December 1996; b. 20 000 and 25 000 flight cycles at 01 July 1996 - before 10 January 1997; and c. 15 000 and 20 000 flight cycles at 01 July 1996 - before 10 February 1997. This Directive has effect from 10 October 1996. Background: Cracking has been discovered in these lap joints before the inspection threshold mandated in the Structural Integrity Programme, and before the cycles threshold of AD/F28/75. This Directive requires a one time inspection of the area using the existing LFEC technique and if cracking is found, installation of a terminating repair.