As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
POS - FLT 602 - AT TOP OF DESCENT, AIL AND RUDDER MANUAL REVERSION LIGHTS CAME ON. SYSTEM PRESSURE DROPPED TO ZERO AND FLUID QUANTITY WAS AT STANDPIPE LEVEL. EMERGENCY PROCEDURES WERE FOLLOWED. AIRCRAFT LANDED AT POS WITHOUT INCIDENT. REMOVED AND REPLACED SLOT CONTROL VALVE O-RING OPS NORMAL IAW MM 27-80-4. (M)