COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Mitsubishi MU-2 Series Aeroplanes AD/MU-2/44 Split Radio Bus 13/89 Applicability: MU 2B25: S/N 239 through 273. MU 2B-30/35: S/N 505 through 599. Requirement: Action IAW MHI MU 2 SB 069/24-006 in conjunction with AD/MU 2/43. Compliance: Prior to 31 March 1990. Background: This AD resulted from a request by the National Transportation Safety Board (US) who while investigating a number of fatal MU 2B accidents, concluded that pilots were becoming confused in the operation of the interrupt/disconnect switches for the electric pitch trim and autopilot systems.