As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIR TURN BACK DUE TO LH HYD FAIL CAS AFTER TAKEOFF FROM KAUS, WITH ALL LEFT SYSTEM QUANTITY LOST; A LARGE AMOUNT OF HYDRAULIC FLUID WAS FOUND LEAKING ON THE GROUND AFTER LANDING. REPLACED RH SIDE STAY ACTUATOR RETURN LINE HOSE IAW GULFSTREAM G450 AMM 32-14-01. LEAK CHECK GOOD, NO DEFECTS NOTED.