As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON APPROACH A SPLIT FLAP CONDITION OCCURRED. WHEN FLAPS WERE SELECTED DOWN, THE LT INBOARD FLAP REMAINED IN THE FULL UP POSITION. ALL OTHER FLAPS EXTENDED NORMALLY. CAUSE WAS DETERMINED TO BE A DRIVE GEAR RETAINING NUT THAT HAD BACKED OUT UNDER AIR LOAD IN THE LT INBOARD FLAP ACTUATOR.