On June 14, 2001, at 2005 central daylight time, an experimental amatuer-built VanderBeek Christen Eagle II, N80VB, piloted by a commercial pilot, impacted a corn field while performing aerobatic maneuvers. Visual meteorological conditions with convective activity in the area prevailed at the time of the accident. The 14 CFR Part 91 personal flight was not operating on a flight plan. The pilot and passenger were seriously injured. The local flight originated from Riley's Field Airport (LL51), Plainfield, Illinois, at 1945. A witness located approximately one mile from the accident site observed the airplane performing hammerheads and rolls when a gust front came through; at which time, the wind went from 4-5 mph to 25-30 mph within seconds, in what he described as "a very short length of time". He then lost sight of the airplane as it descended behind a row of trees. The accident occurred within a minute from the time that the gust front came through. The pilot reported not remembering the circumstances leading to the accident or the nature of the accident. Within the same report, the pilot stated that he was wearing his restraint system while he occupied the rear seat of the tandem cockpit. He also reported that there was no mechanical malfunction failure. The Aurora automated surface observing system, located approximately 14 nm northwest of the accident site, recorded at 1953, wind from 230 degrees at 14 knots gusting to 22 knots with lightning to the distant south and southwest. The DuPage automated surface observing system, located approximately 18 nm north of the accident site, recorded a special weather observation at 2035, which indicated: winds from 240 degrees at 35 knots gusting to 40 knots, 1 1/2 sm visibility with heavy thunderstorms, rain showers and frequent lightening. The thunderstorms were to the southwest moving towards the northeast. The main wreckage was located approximately 0.8 nm east of LL51 in a cornfield with east/west rows. The fuselage was orientated on a tail to nose magnetic heading of 168 degrees and at the eastern edge of the wreckage path which extended approximately 23 feet along a magnetic heading of 108 degrees. Ground scarring along the wreckage path extended from the western edge of the wreckage path for approximately 15 feet to an area of undamaged corn stalks, which surrounded the main wreckage. The wings, horizontal and vertical stabilizers and engine remained attached to the airframe. The right wings were folded underneath the fuselage and oriented in the lateral direction towards the left side of the fuselage. Flight control continuity from the elevator, rudder and ailerons of all four wings was confirmed to the cockpit. The cockpit was separated at a point beginning roughly at the forward edge of the front seat. Both seats were equipped with a 5-point harness restraint system. The engine remained attached to the airframe with its controllable pitch propeller fractured in several pieces which were located along the wreckage path. The engine was rotated by hand through the propeller hub, and air was expelled from all cylinders and engine continuity confirmed. Electrical continuity from each lead of the top harness was also confirmed. The cockpit fuel selector was a two position selector, "Fuel On" and "Off" and was equipped a manual fuel pump system or wobble pump, which consisted of a pump handle located next to the aft pilot seat. The pump handle was actuated several times and a blue liquid, consistent with aviation fuel, squirted out from the main fuel line exiting the engine firewall. The fuel selector was selected to the "Fuel On" position. The magnetos were in the "Both" position with the mixture and propeller controls in their forward positions. The rear and front seat throttle controls were noted to be in the midrange position. The Federal Aviation Administration and Textron Lycoming were parties to the investigation.