What was found
PDIS 316 29-02 5970 23FEB21 MEM FACT U "ENROUTE TO KMEM LEVEL 1 "HYD 3 ELEV OFF" ALERT ILLUMINATED. HYD 3 WAS AT 4.3 AT THE TIME. HYD 3 CONTINUED TO DECREASE TO 3.0. GEAR EXTENDED W/GEAR HANDLE AND FLAPS & SLATS DEPLOYED OKAY. MADE FLAPS 35/EXT LANDING KMEM RWY 10C. HYD 3 WENT TO 0.4 AT GEAR EXTENSION WITH LEVEL 3 HYD FAIL ALERT. (D.L.W.)" SHGN 23FEB21 18:03 MEM U ACFT RETRIEVED FROM RWY 18C AND TOWED TO GATE 826. WILL TROUBLESHOOT AFTER OFFLOAD. PRIMARY TRIM CONTROL VALVE. WITH SYSTEM 3 HYD SERVICED, OPERATED HORIZONTAL STABILIZER TRIM REF AMM 27-40-00-2. NOTED LARGE LEAK FROM HYDRAULIC LINE TO UPPER PRIMARY TRIM CONTROL VALVE P/N AJK7004-759. FOUND FITTING 'B'-NUT LESS THAN FINGER TIGHT (ALMOST COMPLETELY DISCONNECTED). DISCONNECTED LINE, INSPECTED 'B'-NUT AS WELL AS MATING SURFACE ON VALVE UNION. NO DISCREPENCIES WERE FOUND. RECONNECTED & RE-TORQUED LINE IAW AMM 20-50-01-2. RE-PREFORMED HORIZ STAB OPS CHECKS REF AMM 27-40-00-2.NO LEAKS NOTED. CLOSED MAIN GEAR DOORS. AIRCRAFT O.K. FOR SERVICE.