What was found
THE HYDRAULIC SYSTEM NR 3 ELEVATOR OFF CAUTION LIGHT ILLUMINATED AND THE NR 3 HYDRAULIC QUANTITY BEGAN TO DECREASE WHILE EN ROUTE FROM FRA TO EWR. SHORTLY AFTERWARDS, THE NR 3 LEFT HYDRAULIC PUMP PRESSURE LOW LIGHT ILLUMINATED. ALL APPROPRIATE CHECKLISTS WERE ACCOMPLISHED AND THE AIRCRAFT WAS DIVERTED TO LGW WHERE IT LANDED WITHOUT INCIDENT. MAINTENANCE FOUND THE NR 3 HORIZONTAL STABILIZER TRIM MOTOR LEAKING. THE STABILIZER TRIM MOTOR WAS REMOVED AND REPLACED. THE NR 3 HYDRAULIC SYSTEM WAS SERVICED. LEAK AND OPERATIONAL CHECKS WERE GOOD.