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/A320/98 Nose Landing Gear (NLG) - Steering 6/99
Applicability: All Airbus Industrie model A319, A320 and 321 aircraft without Airbus Industrie modification No. 23740 (in production from 03 April 1999) or Airbus Industrie Service Bulletin A320-32-1197 (embodied in service).
Requirement: 1. Perform corrective actions in accordance with instructions in Airbus Industrie Service Bulletin A320-32-1197.
2. Ensure that replacement Hydraulic Control Units are not Part Number C24736000 and C24736001. All of these units are to be reworked in accordance with Airbus Industrie Service Bulletin A320-32-1197 prior to re-identification and installation on any aircraft.
Note: DGAC 1999-124-129 (B) dated 24 March 1999 refers.
Compliance: 1. Before 03 April 2000.
2. Prior to fitment of a replacement Hydraulic Control Unit.
This Airworthiness Directive becomes effective on 17 June 1999.
Background: One operator experienced three events when the aircraft landed with the nose wheel turned to 90 degrees. Investigation revealed that the two O-ring seals fitted to the electro hydraulic distributor which controls the hydraulic supply to the steering control module 6GC were extruded due to ageing or the absence of a back up ring. This defect allowed permanent pressurisation of the steering actuator through the steering selector valve and the possibility of the nose wheel rotating through 90 degrees. This directive introduces new seals into hydraulic control module 6GC to prevent an occurrence of such a defect.