Narrative:

I was preparing to enter the pattern for landing and lowering the landing gear [when] I found that the left gear leg was not locked. I cycled the gear several times; even attempting to assist the gear mechanism with my hand to make it into over-center; fully locked position. After trying for 10 minutes with no success I proceeded to land the plane.touchdown and subsequent roll-out went without incident. After the tail wheel was down I still had approximately 100 yards of runway left before the first taxiway. I continued down the runway; taxiing at 10 mph. At approximately the halfway point (50 yards) the left landing gear leg gave way and retracted. This is a hull-type amphibian so when the gear leg retracted; the plane dropped onto the edge of the fiberglass hull on that side and started to slide on the left side while still rolling on the right landing gear. This was an unequal action causing the plane to slide/turn sideways. I stopped the engine and the plane slid to a stop in about 20 feet in the center of the runway.I got out immediately and several people who had been watching the landing began walking over. When they go close enough I told them I needed 2 floor jacks and a few blocks of wood to raise the hull so we could put the leg into down and locked position; allowing me to taxi the rest of the way off the runway.within a few minutes; they had returned with the jacks and blocks and we did just that. I then started and taxied the plane the remaining 50 yards and off the runway to the main ramp.during the time the people were assisting me with the plane; the airport manager arrived (someone had called him as it was after his shift) and he closed the runway until I had taxied off. The runway was closed for about 10 minutes.within 2 hours of the incident; I had secured the gear leg in locked position and the airplane was ready to fly again. I also disabled the power to the gear retraction mechanism since the gear was not functional so all the landing gear would stay in down and locked position.during this process I learned that the bracket that had failed causing the gear leg to collapse was what kept the gear in the down position during landing and roll out. It was the load of all the aircraft weight at taxi that had been too much for the bracket; causing it to fail (remember that this bracket was taking the load because the gear was not in the over-center position). If I ever had a similar problem and was forced to land under the same conditions; I would keep the speed up on roll out thereby keeping the tail up and most of the aircraft weight off the landing gear until reaching a taxiway. At that point I would let the speed decrease allowing the tail wheel to come down and then begin taxiing. This would keep the full weight off that bracket until I was nearly off the runway; thereby minimizing the chance of the gear collapsing on the runway.in discussing the incident with a fellow [amphibious] pilot with several hundred hours in type; he pointed out that if I was able to go to a nearby lake or river and land there; I could have worked with the landing gear near the shore while the plane was still floating and look for and possibly solve the problem that was preventing the gear from reaching the fully locked position.both of these things are now options should this type of incident ever occur again.additionally; in repairing the gear system; I am replacing the failed bracket and the still-good bracket with a stronger one than the factory one to also give me more strength should this ever happen again.note: in this case there wasn't a nearby lake or river adequate for landing where I could have affected repairs but now that is an option I will be ready to exercise should the need arise.

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Original NASA ASRS Text

Title: The pilot of an amphibian experimental aircraft identified a potential landing gear issue prior to landing. During the landing rollout; one main landing gear collapsed.

Narrative: I was preparing to enter the pattern for landing and lowering the landing gear [when] I found that the left gear leg was not locked. I cycled the gear several times; even attempting to assist the gear mechanism with my hand to make it into over-center; fully locked position. After trying for 10 minutes with no success I proceeded to land the plane.Touchdown and subsequent roll-out went without incident. After the tail wheel was down I still had approximately 100 yards of runway left before the first taxiway. I continued down the runway; taxiing at 10 mph. At approximately the halfway point (50 yards) the left landing gear leg gave way and retracted. This is a hull-type amphibian so when the gear leg retracted; the plane dropped onto the edge of the fiberglass hull on that side and started to slide on the left side while still rolling on the right landing gear. This was an unequal action causing the plane to slide/turn sideways. I stopped the engine and the plane slid to a stop in about 20 feet in the center of the runway.I got out immediately and several people who had been watching the landing began walking over. When they go close enough I told them I needed 2 floor jacks and a few blocks of wood to raise the hull so we could put the leg into down and locked position; allowing me to taxi the rest of the way off the runway.Within a few minutes; they had returned with the jacks and blocks and we did just that. I then started and taxied the plane the remaining 50 yards and off the runway to the main ramp.During the time the people were assisting me with the plane; the airport manager arrived (someone had called him as it was after his shift) and he closed the runway until I had taxied off. The runway was closed for about 10 minutes.Within 2 hours of the incident; I had secured the gear leg in locked position and the airplane was ready to fly again. I also disabled the power to the gear retraction mechanism since the gear was not functional so all the landing gear would stay in down and locked position.During this process I learned that the bracket that had failed causing the gear leg to collapse was what kept the gear in the down position during landing and roll out. It was the load of all the aircraft weight at taxi that had been too much for the bracket; causing it to fail (remember that this bracket was taking the load because the gear was not in the over-center position). If I ever had a similar problem and was forced to land under the same conditions; I would keep the speed up on roll out thereby keeping the tail up and most of the aircraft weight off the landing gear until reaching a taxiway. At that point I would let the speed decrease allowing the tail wheel to come down and then begin taxiing. This would keep the full weight off that bracket until I was nearly off the runway; thereby minimizing the chance of the gear collapsing on the runway.In discussing the incident with a fellow [amphibious] pilot with several hundred hours in type; he pointed out that if I was able to go to a nearby lake or river and land there; I could have worked with the landing gear near the shore while the plane was still floating and look for and possibly solve the problem that was preventing the gear from reaching the fully locked position.Both of these things are now options should this type of incident ever occur again.Additionally; in repairing the gear system; I am replacing the failed bracket and the still-good bracket with a stronger one than the factory one to also give me more strength should this ever happen again.Note: in this case there wasn't a nearby lake or river adequate for landing where I could have affected repairs but now that is an option I will be ready to exercise should the need arise.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.