COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Boeing 727 Series Aeroplanes AD/B727/110 Amdt 2 Wing Centre Section Front Spar Web 2/93 Applicability: Line Numbers 1 to 191. Requirement: Visually inspect the wing centre section front spar web in accordance with Boeing Service Bulletin 727-57-0107 Revision 6. Note: FAA AD 90-20-02 refers. Compliance: If back to back angles were installed before 20000 flights: Inspect within 12000 flights after installation of the angles, or within 1000 flights since last inspected in accordance with the previous issue of this AD, or within 1000 flights after 4 February 1993, whichever is the latest. If back to back angles have not been installed, or were installed after 20000 flights: Inspect before 15000 flights, or within 1000 flights since last inspected in accordance with the previous issue of this AD, or within 1000 flights after 4 February 1993, whichever is the latest. Re-inspect at intervals not exceeding 1000 flights, until the doublers and straps have been installed per Boeing Drawing No 65-78836. Background: Fatigue cracks caused by pressurisation cycling have been found in the subject area. Amendment 2 is issued to require further repeat inspections to aircraft that have been previously modified by installing additional angles back-to-back with existing stiffeners, as several of these installations have been subsequently found to crack.