What was found
NR 3 HYDRAULIC QUANTITY DROPPED TO 4.9 GAL. WITH HYDRAULIC 3 ELEVATOR OFF LEVEL 2 ALERT, DECLARED EMERGENCY. APPROACH, LANDING AND TAXI NORMAL. ON BLOCK IN NR 3 HYDRAULIC QUANTITY WAS DOWN TO 3.4 GAL. FOUND PRESSURE TRANSDUCER LEAKING AT SEALS (O-RINGS). MANIFOLD NR 3 LOCATED RIGHT WHEEL WELL. REMOVED AND REPLACED 2 EACH O-RINGS ON HYDRAULIC SYSTEM 3 MANIFOLD PRESSURE TRANSDUCER IAW MD, MM SERVICED NR 3 HYDRAULIC RESERVOIR IAW MD. OPERATIONAL AND LEAK CHECK GOOD, AIRCRAFT CONTINUED SERVICE.