As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TRAINING FLIGHT, LANDING GEAR WOULD NOT EXTEND ELECTRICALLY OR MANUALLY (EMERGENCY EXTENSION). AIRCRAFT LANDED GEAR UP. DURING INVESTIGATION, FOUND BEARING ON ACTUATOR WORM GEAR GALLED AND IN MANY PIECES. WORM GEAR WAS THUS ALLOWED TO MOVE RADIALLY AND BIND THE SECTOR GEAR. MM SECTION 15 INDICATES THAT THIS PART IS TO BE REPLACED OR OVERHAULED EVERY 2000 HOURS.