Incident Overview
The pilot reported that after touchdown, the tail wheel began to shimmy, causing the entire airplane to shake. In an attempt to stop the shimmy, the pilot moved the rudder from side to side. Near the end of the landing roll, the airplane veered to the right. Despite applying left rudder and brake, the pilot was unable to correct the turn, and the airplane continued into the grass.
Sequence of Events
Once on the grass, the left main landing gear collapsed, and the airplane came to rest on its left side. The pilot noted that the tail wheel springs came unhooked as a result of the tail wheel shimmy. The collapse occurred during the landing roll, and the aircraft sustained damage to its left side.
Pilot Actions
The pilot's immediate response to the shimmy involved alternating rudder inputs. When the aircraft veered, he attempted to counteract the turn using left rudder and brake, but these measures were insufficient to prevent the excursion.
Conclusion
The left main landing gear collapsed after the airplane departed the runway surface during the landing roll. The pilot attributed the tail wheel shimmy to the unhooking of the tail springs.