COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Boeing 737 Series Aeroplanes AD/B737/11 Horizontal Stabilizer Centre Section - Rear Spar Upper Chord Attach Lugs 10/86 Applicability: All 737-100, -200 and -200C models with Line Numbers 316 to 322, and 325 and subsequent. Requirement: Inspect in accordance with the Flight Safety Inspection Program specified in Boeing S.B. 737-55-1033. Note: FAA AD 86-12-05 refers. Compliance: (a) Before exceeding 40,000 landings; or (b) Before exceeding 40,000 landings after a chord replacement or modification in accordance with Option 1 of the Requirement Document, whichever is the later, and thereafter at intervals not exceeding 5,700 landings. Background: Cracks in the lugs, if undetected, could lead to loss of the horizontal stabilizer.