As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKEOFF LEFT MAIN GEAR RED LIGHT REMAINED ON. AFTER GEAR RETRACTION RED UNSAFE LIGHT REMAINED ILLUMINATED WITH GEAR HANDLE IN BOTH UP AND OFF. FOUND LT MLG UPLOCK SENSOR AT FAULT. REF MM 32-61-00-101 R/R LT MLG UPLOCK SENSOR REF MM 32-61-21. CYCLED GEAR. ALL INDICATIONS NORMAL.