As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) AIRCRAFT LOSS OIL HYDRAULIC PRESSURE AFTER DROPPING A LOAD OF WATER. AIRCRAFT RETURNED TO WABUSH AIRPORT. TANKER DOORS WERE CLOSED USING EMERGENCY SYSTEM, LANDING GEAR LOWERED USING EMERGENCY SYSTEM. MAINTENANCE DISCOVERED A CHECK VALVE IN RIGHT HAND WING CRACKED IN TWO PIECES CAUSING ALL FLUID TO LEAK OUT OF MAIN SYSTEM.