COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Airbus Industrie A319, A320 and A321 Series Aeroplanes AD/A320/97 Amdt 1 Airborne Ground Check Module Modification 12/99 Applicability: All Airbus Industrie model A320 aircraft which do not have Modification 27728 or 27189 embodied. Requirement: Modify the Airborne Ground Check Module (AGCM) in accordance with the instructions of AIRBUS INDUSTRIE Service Bulletin A320-29-1086. Note: DGAC AD 98-537-124(B) R1 dated 22 September 1999 refers. Compliance: Before 31 December 1999. This Amendment becomes effective on 2 December 1999. Background: During two in-flight events and during one functional check of the AGCM of the Ram Air Turbine, a blockage of the low pressure check valve was observed. Such a blockage could lead to the loss of the blue hydraulic system when using the Ram Air Turbine. This amendment introduces additional applicability criteria. The original issue of this Airworthiness Directive became effective on 25 March 1999.