COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Boeing 747 Series Aeroplanes AD/B747/133 Fuselage - Upper Deck Floor Beams at BS 860 and 980 11/94 Applicability: B747-300, -400 and -100B series aircraft delivered with Stretched Upper Decks (SUD) Line numbers 570 to 843 inclusive and all aircraft modified to have SUD. Requirement: 1. Conduct a high frequency eddy current inspection of the BS 860 and 980 upper deck floor beams at LBL 46.83 and RBL 46.83 in accordance with Boeing SB 747-53-2327 Revision 1. 2. Modify the BS 860 and 980 upper deck floor beams at LBL 46.83 and RBL 46.83 in accordance with Boeing SB 747-53-2327 Revision 1 and Boeing drawing 624U0014. Note: FAA AD 92-24-07 refers. Compliance: 1. Inspect and modify, B747-300, -400 and -100B series aircraft delivered with SUD, before 20000 flights or within 1000 flights of 13 October 1994 whichever is the later. 2. Inspect and modify B747 aircraft modified to have SUD before 20000 flights after the modification or within 1000 flights of 13 October 1994 whichever is the later. Background: Cracking of the floor beams was experienced during the B747-400 full scale fatigue test at 35000 pressure cycles. Inspection and modification in accordance with this AD will extend the fatigue life of the floor beams.