Date: 201909
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Weather elements / visibility: 10
Light: Daylight
Aircraft: Bonanza 33
Operator: Personal
Operating under: Part 91
Flight plan: None
Mission: Training
Flight phase: Landing
Airspace: Class G ZZZ
ATC / advisory: CTAF ZZZ
Reporter organization: Personal
Reporter function: Pilot Not Flying; Instructor
Reporter qualification: Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Private; Flight Crew Commercial
Human factors: Situational Awareness; Workload; Distraction; Communication Breakdown; Human-Machine Interface
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Gear Up Landing
Detector: Person Flight Crew
When detected: In-flight
Result: Aircraft Aircraft Damaged
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: I had a student pilot transitioning to a Bonanza F-33. On [date]; we flew for approximately 1/2 hour working on takeoff and landings. On [date]; we flew approximately 2.2 hours working on takeoff and landing; slow flight; steep turns; and stalls. On the date of the incident; we trained approximately 2 hours before the incident. We did three touch and go's at ZZZ and then headed for ZZZ1. On the way to ZZZ1; I wanted to test the gear-up warning horn. Accordingly; we pulled the power to 19 inches with no horn; then 16 inches with no horn; then 13 inches with no horn and finally all the way to idle with no horn. When discussed with my student (owner of the aircraft); he thought that his serial number was included in aircraft that did not have a gear-up horn and that is why the horn was did not sound off.We continued to ZZZ1 and conducted three touch and go's before heading back to ZZZ. We conducted 4 additional touch and go's before the incident. Setting up for the next full stop landing; a Cessna 172 pulled onto the runway when we turned final. The Cessna 172 did not do a rolling take-off; but instead stopped and lined up with runway before proceeding with departure. I determined that it would not be safe to continue with the approach because I was not sure that the Cessna 172 would be off runway before we landed. Accordingly; I had student abort approach; side step to the right of the runway in order to keep a visual on the Cessna taking off. I retracted flaps and landing gear to gain altitude and crossed mid-field to tear drop back into the pattern behind the departing Cessna 172.We performed a tear drop to the 45 for the downwind to Runway XX behind the Cessna 172. Since the Cessna 172 had cut out in front of us on final approach; both the student and myself were distracted trying to keep a visual on the Cessna 172 and figuring when to turn base without overtaking the Cessna 172 on final approach. During this distraction; we did not perform the GUMPS check on downwind; as we had performed on the previous 10 touch and go's. We slowed down and had to extend the downwind in order to not overtake the Cessna 172 causing us to have an extended final and have a different power management to adjust for the longer final. Again; we were distracted with the power management for the longer final and judging the Cessna 172 in front of us would be clear of the runway before our touchdown. Again; being distracted with the additional power management on the longer file and judging the Cessna 172 in front of us on final; we did not perform the GUMPS check on final as we had performed on the previous 10 touch and go's.Once we knew the Cessna 172 would be clear the runway before our touchdown; we continued on final approach to touchdown. We did normal round out and flare; but did not know gear was up until after we heard the stall warning horn and heard the metal scraping. Once we knew it was a gear up landing; we maintained control of the aircraft as best we could and held nose up as long as possible. Once stopped; I made a radio announcement that we had a gear up landing and blocking the runway. I called the airport manager to make him aware of the incident. He put out a NOTAM closing the runway and called for a crane to lift the aircraft up to lower the landing gear. The crane arrived and lifted the aircraft and landing gear was lowered. Airport manager then simply towed aircraft to ramp.




Synopsis: Flight instructor reported that an inoperative gear horn; distraction; and deviation from landing checklist resulted in a gear-up landing.