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-2/47 Elevator and Rudder Trim Tab Spar 11/90 Applicability: All models as detailed in the Requirement documents. Requirement: As applicable by serial number, action in accordance with 1. Mitsubishi Service Bulletin MU-2 No 207, dated 20 May 1988, or 2. Mitsubishi Service Bulletin MU-2 No 068/27-009, dated 12 December 1988. Compliance: Within 100 hours time in service after 1 November 1990 and thereafter at intervals not to exceed 300 hours time in service. Background: Two 8.2 inch cracks have recently been reported emanating from the spar radius, which caused separation of the rudder trim tab skin, and subsequent inflight oscillation of the rudder.