As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING LANDING GEAR INSPECTION GEAR ON LT MAIN WOULD NOT RELEASE FROM UP POSITION UNLESS USING EMERGENCY SYSTEM. TROUBLE SHOOTING THE GEAR SYSTEM FOUND THE LEFT UPLOCK SWITCH WAS NOT RELEASING WHEN GEAR SELECTED TO DOWN POSITION. PROBABLE CAUE COULD BE THE WIRES TO THE UP LOCK ASSEMBLY RELAY HAVE FAILED. UPLOCK ASSEMBLY WAS REMOVED AND INSTALLED A NEW UPLOCK ASSEMBLY. OPERATION CHECK OF THE GEAR SYSTEM CHECKED NORMAL.