On June 25, 2003, about 0730 eastern daylight time, a John L. Klein Marquart Charger MA-5 experimental amateur-built airplane, N707JK, registered to Global Cub Air Inc., and operated by a private individual, as a Title 14 CFR Part 91 personal flight, crashed in Pierson, Florida. Visual meteorological conditions prevailed, and no flight plan was filed. The private-rated pilot received serious injuries, and the airplane incurred substantial damage. The flight originated in Ormond Beach, Florida, the same day, about 0710. A witness stated that he and the pilot of the accident airplane had both departed from Ormond Beach Airport, Ormond Beach, Florida, and had joined up and flew formation for a few minutes. He said they then separated and flew no more than a mile apart toward Lake Destin, intending to land on the grass strip at Pierson, Florida. He was about 900 to 1,000 feet, and N707JK was about 400 to 500 feet below, in a position forward of his airplane's wing, such that N707JK was in constant view. The witness said he saw left rudder movement on N707JK, and N707JK yawed to the left, yawed to the right, and then the nose dipped slightly and N707JK disappeared immediately in the canopy of trees. Within several seconds the witness said he was over the area where N707JK had disappeared, but he could not see anything due to the trees. He then increased his altitude, and made a radio communications call, declaring an emergency. After the airplane was recovered and examined, the rod end bearing on the elevator push/pull tube was found to have disconnected from the rear cockpit's control stick, resulting in a loss of elevator control. The connecting clevis bolt, castle nut, and cotter key were not recovered.