COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes AD/DHC-8/50 Amdt 1 Ditching Dam Inflation Bottle 12/98 Applicability: DHC-8 aircraft, Models 311, 314, and 315 in the medium and high gross weight configuration incorporating Change Requests CR803SO00001, CR803SO00001-1, CR803SO00002, CR803SO00002-1, CR803CH00046, CR803CH00079, CR803CH00105, CR825CH00847, or CR803CH00051. Requirement: Incorporate de Havilland Modification 8/3154. This modification installs bottle assemblies with part number 410870-3 or -5. Instructions for incorporating de Havilland Modification 8/3154 are detailed in de Havilland Service Bulletin 8-25- 122, Rev A. Note: Transport Canada AD CF-97-21R1 refers. Compliance: Unless already accomplished, before 5 February 1999. This Airworthiness Directive becomes effective on 5 November 1998. Background: During a functional test of the ditching dams on DHC-8-300 aircraft, some dams failed to fully inflate. The cause was determined to be incorrect operation of the inflation cylinder assembly, manufactured by Adams Rite Sabre International. Amendment 1 is issued in response to a revision of the related Transport Canada AD, which adds two Change Requests to applicability and identifies the part numbers of the bottle assemblies installed by the modification. The original issue of this Airworthiness Directive became effective on 26 February 1998.