COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Boeing 767 Series Aeroplanes AD/B767/55 Centre Fuel Tank Override Pumping Unit Diffuser Assembly Applicability: Model 767 line number 1 through 359, 361 and 362. Requirement: Action in accordance with Boeing Alert SB 767-28A0036. Note: Sundstrand Alert SB 5006286-28-A4 refers. Compliance: Prior to 31 May 1991. 7/91 TX Background: On certain S/N override pumping units the brazed joint attaching the diffuser ring to the diffuser sleeve may separate. If this occurred during a dry pump operation an ignition source may occur within the centre tank.