As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
GEAR WARNING HORN WAS INOPERATIVE. AC LANDED WITH LANDING GEAR UP. SUBSEQUENT INVESTIGATION DETERMINED THROTTLE MICROSWITCH WAS MAKING INTERMITTENT CONTACT WHEN ENGAGED AND GROUND CONNECTION WAS INSUFFICIENT. CORRECTED BY REPLACING SWITCH AND REPAIRING GROUND CONNECTION. HORN OPERATION SHOULD BE CHECKED VIA TEST FEATURE DURING PREFLIGHT. (K)