COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Boeing 747 Series Aeroplanes AD/B747/96 Drain Mast Assemblies 7/91 Applicability: Boeing 747 series aeroplanes as listed in Boeing Alert Service Bulletin 747-38A2077, dated 30 August 1990. Requirement: Action in accordance with the Technical Requirements of FAA AD 91-09-11. Note: FAA AD 91-09-11 refers to Boeing Alert Service Bulletin 747-38A2077, dated 30 August 1990. Compliance: Required within 12 months from 11 July 1991. Background: FAA AD action prompted by two reports of fire which may have been caused by the contact of foreign material with drain mast heater elements. This condition, if not corrected, could result in structural damage to the fuselage skin, frame, and stringers, and possible uncontrolled fire.