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-2/31 Cockpit Airconditioning Ducts - Inspection and Modification Applicability: All models MU-2B-26A/-40 with S/Nos. 321SA, 348SA, 350SA to 457SA. 1/84 MU-2B-36A/-60 with S/Nos. 661SA, 697SA to 699SA, 1501SA to 1542SA, 1544SA to 1547SA. Document: Mitsubishi SB No. 040/21-002. Compliance: Prior to issue of the next maintenance release after 21 December 1983. Background: The manufacturer advises that it may be necessary to re-route and modify the airconditioning ducting located above the electrical overhead panel due to the possibility of electrical arcing or shorting occurring in that area.