20200125002319A

The pilot reported that the aircraft was being operated as experimental amateur-built during phase 1 flight testing to determine takeoff and landing characteristics with the owner monitoring aircraft systems and assisting in the testing. When making the eighth landing the approach was slightly high and about 5 knots fast at about 80 mph IAS. The normal approach speed with this aircraft ranges from 65 to 75 mph depending on configuration. During approach with full flaps the aircraft was put into a slip to steepen the decent angle without increasing airspeed, then exited the slip and began to flare the aircraft; landing pitch attitude was achieved and the aircraft was held in the landing pitch attitude as airspeed decayed toward vso. At approximately vso the aircraft touched down on or near the center line with no drift or yaw. The aircraft began ?roll out.? After a second or two, the pilot felt the rudder pedals jerk, the nose began to yaw left rapidly, and it did not respond to application of right rudder. The aircraft left the runway and stopped facing and almost perpendicular to the runway after 270 degrees of rotation.

The right main landing gear wheel failed in the center. The axle and axle bearing was pulled from the wheel when the wheel failed. The tail wheel was torn from the bottom of the fuselage and the tail wheel spring attachment bolt was bent over opposite the direction of the yaw. The bolt threads contained thread material for the nut, which was not found. The tail wheel spring retaining plate (shackle) was found near the aircraft with one bolt missing and one bolt sheared. One spring was disconnected from the tailwheel steering horn and its spring ends were significantly more open that the spring that remained on the horn. The aircraft builder reported that the tail wheel steering spring had fallen off twice during taxi testing.