COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Boeing 747 Series Aeroplanes AD/B747/58 Hydraulic Fuse 10/87 Applicability: Model 747 series aircraft as listed in Boeing Service Bulletin 747-29-2063. Requirement: In accordance with Boeing Service Bulletin 747-29-2063 dated 23 December 1986 or later FAA approved revision. Compliance: Prior to 31 July 1989. Background: The installation of a hydraulic fuse in the No. 4 hydraulic system is prompted by the incident in which all four hydraulic systems were lost when failure of the rear pressure bulkhead resulted in loss of the vertical stabiliser.