As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
HYDRAULIC FAILURE IN CRUISE, HYD PRESS ZERO WITH MAIN PUMPS OR AUX PUMP, QUANTITY AND TEMP OK. FOUND MAIN HYD RESERVOIR CAP MISSING. REFILLED 15 GAL OF HYD FLUID. PERFORMED COMPLETE HYD POWER SYSTEM IAW MM 29-00. INSTALLED AND SAFETIED NEW CAP.