What was found
DURING APPROACH FOR LANDING, THE PILOT WAS UNABLE TO GET THE LANDING GEAR TO EXTEND, EITHER NORMALLY OR USING THE EMERGENCY GEAR EXTENSION SYSTEM. A GEAR-UP LANDING WAS ACCOMPLISHED WITH ONLY MINOR DAMAGE AND NO INJURIES. SUBSEQUENT INVESTIGATION DETERMINED THAT THE COUPLING (P/N B100-06) BETWEEN THE LANDING GEAR MOTOR TRANSMISSION AND THE DRIVE ACTUATOR HAD BROKEN. THE COUPLING HAS NO REPLACEMENT REQUIREMENTS, BUT IS RECOGNIZED IN MOONEY SERVICE INSTRUCTION M20-89 AS A PART THAT COULD FAIL DUE TO AGE HARDENING AND DETERIORATION. THE AIRCRAFT OWNER WAS NOT AWARE OF THIS CONDITION.