COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Agusta A109 Series Helicopters AD/A109/12 Main Landing Gear Stiffening Struts 7/88 Applicability: All A109A and A109AII helicopters as listed in the Requirement document. Requirement: Action in accordance with Agusta Bollettino Tecnico No 109-67. Note: RAI AD 88-37/A109-47 refers. Compliance: Part I of Requirement document: Unless already accomplished; prior to 31 May 1988. Part II of Requirement document: Every 600 flight hours. Part III of Requirement document: Before further flight if cracks are found during compliance with Parts I and II. Background: The manufacturer reports cases of structural damage occurring in the area surrounding the MLG upper brackets. The prime factor for this damage is believed to be looseness of MLG stiffening strut attachment screws. This Directive requires the replacement of the MS 27039-1-08 screws with AN 3-4A bolts and introduces a repetitive inspection to increase the reliability of the MLG system.