As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CLT - FLT 0366 - AFTER TAKEOFF, THE GEAR WOULD NOT RETRACT. CAPTAIN WENT THROUGH PROPER PROCEDURES AND RECEIVED THREE GREEN DOWNLOCK LIGHTS. CREW DECIDED TO RETURN TO CLT. MAINTENANCE RECHARGED THE HYDRAULIC RESERVOIR PRESSURE. HYDRAULIC SYSTEM AND LANDING GEAR OPERATIONS CHECKED GOOD. (X)