COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Fokker F28 Series Aeroplanes AD/F28/55 Amdt 1 Generator Control Units 8/88 DM Applicability: All models fitted with generator control units P/N 914F569-4, -5 and -6. Requirement: 1. Replace all relays P/N 938D848-1 in accordance with Westinghouse service Bulletin 86-401 Revision 1. 2. Install spacer P/N 935A376-1 between all TO5 case style transistors and printed circuit board in accordance with Westinghouse service Bulletin 86-401 Revision 1. Compliance: Requirement 1: Generator control panels fitted to Aircraft: Prior to 14 November 1988. Generator control panels held as spares: Prior to fitment to an aircraft after 14 November 1988. Requirement 2: Whenever any TO5 case style transistor is replaced. Background: Based on data provided by Fokker and various F28 operators it has been determined that a serious reliability problem exists with these control panels. The nature of the problem is intermittent and cannot be detected during normal testing, and the possibility of multiple simultaneous failures cannot be discounted. Amendment 1 to this Directive is issued to clarify the applicability and requirement.