COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Fokker F50 (F27 Mk 50) Series Aeroplanes AD/F50/42 Amdt 1 External Power Connection Relay Fitment 5/91 Applicability: All F 27 MK50 aircraft as listed in the requirement document. Requirement: Action in accordance with the technical requirements of RLD Airworthiness Directive 90-137 dated 14 December 1990. Note: Fokker SB F50-24-015 dated 29 November 1990 also refers. Compliance: As specified in the requirement document. Background: Reports indicate that the potential exists for serious damage to occur to contactors and circuit breakers during ground power to aircraft power change-over. Note: Amendment 1 to this AD is issued to clarify the compliance statement.