COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Boeing 747 Series Aeroplanes AD/B747/49 Vertical Fin Access Cover Installation 6/86 Applicability: All models with line numbers to 625. Requirement: Action in accordance with Boeing SB 747-53A2264. Note: FAA AD 86-08-02 refers. Compliance: Prior to 30 November 1986. Background: The FAA has determined that the vertical fin could be over pressurised to the point of structural failure in the event of failure of the aft pressure bulkhead.