As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CLT - YYZ, DURING TAKEOFF CLIMBOUT THE NLG DOORS WOULD NOT CLOSE DURING RETRACTION. THE A/C RETURNED TO THE FIELD, RECEIVED A VISUAL CONFORMATION FROM THE CONTROL TOWER THAT THE DOORS WERE IN FACT OPEN AND LANDED WITH OUT INCIDENT. MX REPLACED THE SELECTOR VALVE AND CONTROL LEVER BUT DID NOT FIX THE PROBLEM. OLD PARTS WERE RE-INSTALLED AND THEN MX FOUND THE UPLOCK PROX SENSOR HAD A BROKE WIRE. MX REPLACED THE PROX SENSOR AND OPS CHECKD GOOD.