What was found
TWO HOURS INTO FLIGHT THE PILOTS RECEIVED HYD 2 LO PRESS CAS MESSAGE AS WELL AS 0% QTY SHOWING ON THE #2 HYDRAULIC RESERVOIR. CREW RAN THEIR CHECKLISTS AND AIRCRAFT RETURNED TO BASE WITH NO FURTHER ISSUES. WHEN THE AIRCRAFT LANDED, MAINTENANCE FOUND SKYDROL POURING FROM THE PYLON/FIXED COWL AREA. UPON FURTHER INVESTIGATION THEY FOUND THE #2 HYDRAULIC PRESSURE LINE FEED-THROUGH COUPLING AT THE FIREWALL CRACKED NEARLY IN HALF IN THE CENTER AT ITS THICKEST PART. COUPLING REPLACED AND RESERVOIR REPLENISHED. COMPLIED WITH TASK 05-51-11-210-801, GVI OF THE EDP AFTER DRY OPERATION AND FOUND BOTH CASE DRAIN AND PRESSURE FILTERS CONTAMINATED WITH METAL PARTICLES WHICH REQUIRED REPLACEMENT OF THE #2 EDP. AIRCRAFT RETURNED TO SERVICE.