As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER DROPPING RETARDANT ON A FIRE, WHILE AT CRUISE RETURNING TO BASE, MAIN HYDRAULIC SYSTEM FAILURE OCCURRED WITH ASSOCIATED VAPORS IN THE COCKPIT. VISUAL INSPECTION SHOWED NO FLUID PRESENT WITH MAIN SYSTEM PRESSURE READING ONLY ACCUMULATOR PRESSURE. DIVERSION TO ALTERNATE AIRPORT WAS INITIATED AND SUCCESSFULLY ACCOMPLISHED. VISUAL INSPECTION REVEALED THAT THE MAIN HYDRAULIC SYSTEM FILTER BOWL HAD CRACKED AND RUPTURED CAUSING LOSS OF THE MAIN HYDRAULIC SYSTEM FLUID AND PRESSURE.