What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
The operating pilot is also an A&P. After maintenance on a autopilot control he was performing a test flight. During the maintenance flight the auto pilot warning alarm continually sounded. Pilot was returning to ground to check out the system and did not differentiate that the gear up alarm was sounding instead of the autopilot alarm. During the confusion the pilot landed without extending the landing gear.
As the FAA filed it
THE OPERATING PILOT IS ALSO AN A&P. AFTER MAINTENANCE ON A AUTOPILOT CONTROL HE WAS PERFORMING A TEST FLIGHT. DURING THE MAINTENANCE FLIGHT THE AUTO PILOT WARNING ALARM CONTINUALLY SOUNDED. PILOT WAS RETURNING TO GROUND TO CHECK OUT THE SYSTEM AND DID NOT DIFFERENTIATE THAT THE GEAR UP ALARM WAS SOUNDING INSTEAD OF THE AUTOPILOT ALARM. DURING THE CONFUSION THE PILOT LANDED WITHOUT EXTENDING THE LANDING GEAR.