What was found
ON APPROACH AT ABOUT FL 240, THE NR 3 HYD QTY INDICATION WENT FOM 75% TO ZERO PERCENT FOR ABOUT 5 MINUTES AND RETURNED TO 75%. LANDING UNEVENTFUL. AT GATE IN INDICATES 75% NO CAUTION OR WARNING LIGHTS EMERGENCY CHECKLIST INDICATED NO CREW ACTION. AIRCRAFT REMOVED FROM SERVICE. INSP #3 HYD SYS IAW AMM 29-12-00-210-802 FOUND RESEVIOR QTY TRANSDUCER CONNECTOR LOOSE AND DIRTY. CLEANED AND SECURED THE CONNECTOR. PERFORMED AN OPS CHECK IAW AMM 29-12-01-710-801. OPS CHECKED GOOD. COULD NOT DUPLICATE FAULT. RETURNED TO SERVICE.