What was found
AFTER TAKEOFF RETRACTED GEAR AUTOTHROTTLES DISENGAGED, SAW BOTH THE MAIN GEAR ON THE FORWARD PANEL SHOWED DOWN & LOCKED. NOSE GEAR STOWED UP AND LOCKED, OVERHEAD INDICATION SHOWED UP & LOCKED. PROXIMITY DETECTOR UNIT FAULT CODE INDICATES INTERNAL FAULT. REMOVED AND REPLACED PROXIMITY DETECTOR PROCESSING UNIT PER AIRBUS M/M 32-31-71-4, OPS CHECKED NORMAL. ON LANDING GEAR DOOR FWD PANEL-B INOP. PERFORMED AUTOTHROTTLES CHECK AS PER M/M 22-37-00-02. PERFORMED AUTOTHROTTLES SYSTEMS LAND TEST IAW AIRBUS MM 22-40-00. AUTOTHROTTLES REMAINED ENGAGED.