COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES AMD Falcon 50 and 900 Series Aeroplanes AD/AMD 50/5 Aft Toilet and Frame 25 Water Drainage 2/91 DM Applicability: All Model 900 Aircraft. Requirement: 1. Action in accordance with the technical requirement of DGAC AD 90-170-009 (B) Part 1. 2. Action in accordance with the technical requirement of DGAC AD 90-170-009 (B) Part 2. Note: Dassault Aviation SB's F900-57, F900-82 and F900-83 refer. Compliance: 1. Prior to 13 February 1991. 2. Prior to 13 November 1991. Background: This AD is raised in response to the Country of origin AD which requires checks and modifications designed to eliminate the accumulation of water in the area of box structures surrounding the flight controls at frame 25.