As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIR TURN BACK. DURING LANDING GEAR RETRACTION, THE CREW RECEIVED A HYDR WARNING LIGHT FOR THE BLUE HYDR SYS. THEY ALSO OBSERVED THE SYS INDICATED '0' PRESSURE. AFTER RETURNING TO THE AIRPORT THE CREW DISCOVERED THE CIRCUIT BREAKER POPPED. MAINT FOUND THE BLUE SYS PUMP CAUSED THE CIRCUIT BREAKER TO POP. BLUE HYD SYS, PUMP REPLACED.