COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Boeing 747 Series Aeroplanes AD/B747/76 Amdt 1 H-11 Steel Bolts 7/90 Applicability: Model 747 with line numbers 001 through 648. Requirement: 1. Visually inspect H-11 steel bolts for cracks or fractures at locations in accordance with Boeing SB 747-51-2043 Rev 1. 2. Replace all H-11 steel bolts with Inconel 718 bolts at locations in accordance with Boeing SB 747-51-2043 Rev 1. Note: FAA AD 89-23-07 refers. Compliance: For Requirement 1: Prior to exceeding 4 years since date of manufacture or within 15 calendar months after 22 February 1990, whichever occurs later, and thereafter at intervals not exceeding 18 calendar months until H-11 bolts are replaced with Inconel 718 bolts. For Requirement 2: Prior to 22 February 1994. Background: Country of origin AD. Fracture or cracking of H-11 steel bolts at critical locations has been reported. This condition if not corrected could result in severe structural damage. Amendment 1 references the latest revision to the Requirement document.