On October 8, 2004, about 1800 central daylight time, an experimental amateur-built tailwheel Sinclair Zenith CH 701 airplane, N701TD, sustained substantial damage when the airplane nosed over during a landing at a private airstrip near Augusta, Kansas. The personal flight was operating under 14 CFR Part 91. Visual meteorological conditions prevailed at the time of the accident. No flight plan was on file. The pilot reported no injuries. The flight originated from a private airstrip near Augusta, Kansas, at 1750. The pilot's accident report stated: On touch down at private strip, landing slightly heavy but nothing excessive. Left main wheel contacted a slight depression and the axle separated. Left gear mainspring dug in causing plane to nose over [and] rotate to the left. Left over momentum caused the right wing to then strike the runway. After stopping, the tail then dropped back onto the ground. The pilot stated that there was 68.5 hours of total time on the axle assembly and his safety recommendation stated that the "accident would not have happened if the axle assembly have been designed with adequate structure ... ." Matco Mfg, the axle manufacturer, was contacted. The manufacturer stated that ownership changed in November of 2000. The earlier company produced the WHLA7 Flange Mount Axles shipped with the accident airplane's kit. The current company designed the same model axle to have a "reinforcing ring welded to the base at the axle flange interface and the larger diameter hole in the flange base that accepts the axle stub." The manufacturer issued a Service Bulletin SRV101804 that showed the new design and an exchange program. That service bulletin is available through their website, www.matcomfg.com, on its technical support page and is appended to the docket material associated with this case.