What was found
DURING GEAR UPLATCH CHECK AFTER TAKEOFF, THE RIGHT HYDRAULIC SYSTEM FLUID QUANTITY WENT TO ZERO. GEAR DOOR OPENED AND MAIN LANDING GEAR EXTENDED AS THE HYDRAULIC SYSTEM FAILED. CREW ENSURED GEAR WAS PROPERLY EXTENDED PER COM. FLIGHT RETURNED TO MDT AND LANDED SAFELY. MAIN GEAR DOORS WERE DAMAGED ON LANDING. MAINTENANCE FOUND THE PRESSURE RELIEF VALVE IN THE RIGHT WHEEL WELL LEAKING. REPLACED THE PRESSURE RELIEF VALVE, BOTH THE ELECTRIC AND ENGINE DRIVEN HYDRAULIC PUMPS AND ASSOCIATED FILTERS, AND GEAR DOORS. RESERVICED THE SYSTEM. LEAK AND OPERATIONAL CHECK GOOD. AIRCRAFT RETURNED TO SERVICE.