COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Boeing 747 Series Aeroplanes AD/B747/95 Wing Leading Edge Duct 6/91 Applicability: Model 747 series, line positions 2 through 707; except model 747-400 series. Requirement: Action in accordance with the Technical Requirements of FAA AD 91-06-08 Amdt 39-6928. Compliance: As specified in the Requirement document with a revised effective date of 13 June 1991 for Australian registered aircraft. Background: This Directive is raised to reflect the above FAA AD amendment which is prompted, in part, by the discovery that the existing AD (88-17-07), incorrectly states that the stress relieving procedure constitutes terminating action for titanium T-ducts. Additionally, the FAA has determined that, in the interest of continuing airworthiness, the terminating action must be mandatory and that a proof pressure test must be required. Cracked or ruptured ducts, if not corrected, could lead to damage to wing leading edge panels and associated problems. Effective date required by the FAA is extended by two months.