As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT NR 3172 - ON APPROACH TO DTW, THE LEFT GEAR GREEN LIGHT FAILED TO ILLUMINATE AFTER GEAR EXTENSION. THE CREW PERFORMED AN ALTERNATE EXTENSION AND ALL INDICATIONS WERE SATISFACTORY. MAINTENANCE REPLACED THE LEFT UPLOCK ACTUATOR. SYSTEM OPERATED SATISFACTORILY. (M)