Date: 202107
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: VMC
Weather elements / visibility: 10
Light: Daylight
Aircraft: M-20 T Predator
Operator: Personal
Operating under: Part 91
Flight plan: VFR
Mission: Personal
Flight phase: Landing
Airspace: Class C ZZZ
ATC / advisory: Tower ZZZ
Aircraft component: Gear Extend/Retract Mechanism
Component problem: Malfunctioning
Reporter organization: Personal
Reporter function: Single Pilot
Reporter qualification: Flight Crew Commercial; Flight Crew Instrument; Flight Crew Multiengine
Human factors: Communication Breakdown; Troubleshooting
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Ground Strike - Aircraft
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Aircraft Aircraft Damaged; Flight Crew Landed in Emergency Condition; Flight Crew Requested ATC Assistance / Clarification; General Maintenance Action
Contributing factors: Aircraft; Human Factors
Primary problem: Ambiguous

Narrative: I am the owner of a Mooney M20E and have >300 hours in this plane. The flight in the late afternoon was a demonstration flight for a friend of mine who is considering beginning pilot training. He has done informal training many times over several years including with me; and has excellent instincts and innate skills that indicate he will be an excellent pilot. In addition; he has significant knowledge about airplanes; airplane systems and general aeronautical/ aviation information. Weather conditions were VFR and not challenging in any way. There were some mild clouds and precipitation in the area but we had no difficulty avoiding them throughout the flight.I flew left seat and handled all engine controls and critical phases of flight; takeoffs; landings; radio calls; etc. He had controls for much of the enroute time and legs of traffic patterns. We did standard maneuvers; mostly practice traffic patterns and landings at ZZZ1; which is close to ZZZ and is the most commonly used training field for many pilots out of ZZZ; including myself. We did three touch and goes and one full stop/ taxi back at ZZZ1. There was no indication of a gear problem for any of these several extensions or retractions. I have very recently done solo training flights with similar or greater numbers of gear extensions and retractions in a similar span of time with no indication of problem. After close to an hour of flying; we returned toward ZZZ for our final stop. We entered a long right base for Runway XXR; and at the appropriate time put the gear switch down. For the first time ever in this plane that I know of; there was a gear extension problem. The gear motor activated and could be felt extending the gear. It seemed mostly normal; but perhaps a little louder/ more forceful than usual. It stopped abruptly; it seemed to have taken a usual amount of time; but the gear on this plane do normally extend quickly and I could not be certain the motor had run as long as usual. The two gear down lights (one on the panel and one on the floor) did not illuminate. The gear actuator circuit breaker had popped out. I tried resetting the circuit breaker twice; but it did not stay in. The gear switch had no effect at this point; as expected with the circuit breaker tripped. The feel of the plane in flight felt as though the gear were down with the expected amount of drag.I advised ZZZ tower that we were breaking off the approach for troubleshooting of a gear problem; and headed generally north of the field in coordination with the controller. I pulled out the Owner's Manual; and my passenger assisted in reviewing the manual gear extension procedure; with which I am very familiar. I have practiced this on the ground a few times over the years at the time of annual inspection with the plane on jacks. I have also practiced it in the air at least once in this plane.With my passenger reviewing the steps out loud for me; I extended the gear manually. The hand crank did not reach a stopping point and the gear down lights did not illuminate. I checked the visual floor indicator; which is there as a backup in case of electrical failure; and the 'GEAR DOWN' sign was visible as normal when the gear extend; with the alignment bars lined up normally as per my memory of how they typically line up. Many additional cranks on the manual extension handle on several more tries had no further effect on anything that I could tell. We were concerned we might have a broader electrical problem of some type leading to failure of the indicator lights; even though the gear appeared to be fully extended. I checked another indicator light on the panel in the same cluster as the 'Gear Down' light (the 'Ram Air' light); which was working properly. I could find no other signs of electrical failure on board. There was no smell or sign of smoke.At this point; I contacted ZZZ tower and coordinated a low pass down Runway XXR to get a visual check of the gear. The tower controller was ableto see the gear well and reported all three appeared to be fully extended. The plane was performing well and maintaining control was not an issue. I was able to aviate; navigate and communicate easily and without difficulty; and to go through the appropriate manual gear extension procedure with plenty of time and focus. My passenger remained very calm; focused and helpful throughout. Neither of us became anxious or nervous; and we were able to communicate well and work together well. He was an asset to me functioning as part of the crew; even without formal pilot training. The ZZZ controller(s) likewise were extremely responsive; helpful and professional.I did not seem to have any additional options to try to get the 'Gear Down' lights to illuminate. I was fairly confident that the gear were fully extended. We were in no immediate danger; and there seemed to be no other emergency reason to land prematurely; although the possibility of some larger electrical system problem remained in my mind. As such; I decided that spending extra time in the air for additional attempts at troubleshooting was no longer wise and that we should land safely while conditions were good.The landing on Runway XXR was smooth; well controlled and uneventful. The wind was nearly straight down the runway and was light. I most often land with no flaps; and chose to do so in this case as well. I made sure to land with excellent technique; touching down gently just above stall speed; well aligned with the center line and with minimal control inputs. I made sure not to use the brakes; and I elected not to use the elevator for aerodynamic braking; as I wanted to avoid any unnecessary forces on the gear. I allowed the plane to roll out long on the runway; and all appeared to be going well. I let the tower know that I intended to roll out long due to the unknown status of the gear. Runway XXR is 7;500 feet long; I touched down not far past the numbers; and rolled out nearly to taxiway 1 for a total rollout distance of about 3;500-4;000 feet.After we had dissipated most of our forward speed without incident or sign of additional problem; I began a very gentle right turn toward the 'high speed' exit for taxiway 1. At that point; the plane began to settle toward the ground toward the left; with the front and right settling down very quickly after. The prop struck the runway and the engine quit; the plane skidded about 30 feet and came to a stop at a mild angle off center line. The impact with the runway was surprisingly soft from our standpoint. I quickly shut off the master switch; magneto switches; and fuel selector; and we exited the plane quickly and easily. There was no fuel spillage; smoke or fire. Neither of us sustained any injury of any kind.Using a heavy boom truck; we were able to gently lift the plane off the runway via the engine mount. I was able to easily manually extend the gear fully; and again was unable to get the 'Gear Down' lights to illuminate despite the gear being verified fully down; and the manual floor indicator properly aligned. While being towed away; the plane again settled to the ground toward the left when initiating a fairly gentle slow turn to the right. This time; only the left gear folded.At the time; shortly after; and for the next day or two I believed that I had properly pushed the crank forward to engage the manual gear extension mechanism and allow the handle to work properly. This is one of the basic few steps needed in the manual gear extension procedure; and I had done it many times. It is a small handle and lever located at approximately the left side of the left pilot's knee; and is easily reachable with your left hand. After reflecting on the events and going back to visit the plane; in fact I had not properly pushed that lever all the way forward. It appears that the manual gear extension mechanism will apply enough lowering force even when not properly engaged to allow the gear to fully or nearly fullyextend; but without the crank properly engaged it appears that you cannot get enough force to fully lock the gear in place.At the time of the [event]; although I and my passenger were under good control and responding well to the situation; I was approaching or beyond 14 hours since I had woken up and gone to work early that morning. I believe that pushing the end of my duty day; as well as familiarity with the procedure and not double checking myself that I had followed every step properly were contributing factors in my failure to fully lock the gear. I believe I could have prevented the gear collapse had I followed the checklist and double checked every step.We have not yet jacked the plane and examined all of the relevant components. Whether or not there is some other structural damage to the gear extension mechanism or any of the components involved; and whether or not we are able to ultimately demonstrate that the gear down lights were or were not in fact working; it does not change the fact that I did not properly complete one of the necessary steps on the checklist for manual gear extension. I also failed to catch this omission with a thorough review of the procedure and circumstances after the gear lights failed to come on. I allowed myself to give too much weight to the possibility of an indicator failure and did not continue to troubleshoot more when I have the ability to do so. I also believed that my familiarity with the procedure was sufficient that I did not consider that I might have omitted or failed to properly complete a step.As I reflect on this; it gives me a sense of humility and a reminder of my own fallibility; and reinforces that I need to double check checklists and critical steps at all times. My belief that my left hand had done what it was supposed to with respect to the one missing step was simply inaccurate. I could have and should have caught the error with a careful review of the circumstances; and there was not an emergency pressing need to get the plane on the ground immediately. I will carry this lesson for the rest of my life. Fortunately; no one was injured; and the mechanical and financial damage to the plane are the only costs. But it is still a humbling fact that I did a basic part of managing my aircraft incorrectly and caused damage as a result. In another circumstance; I or someone else could have been hurt with such an error. I will redouble my efforts to be meticulous for procedures; checklists; and review of critical items at all times. In addition; I will be more careful with respect to aircraft operations beyond 12 or 13 hours since waking up in the morning on any particular occasion.




Synopsis: Pilot reported landing gear failed to indicate extended and during alternate extension procedures; communications problems and failure to follow check lists resulted in the landing gear collapsing on landing roll out.