On July 27, 1994, about 1607 central daylight time, a Cessna 140 airplane, N9409A, sustained substantial damage when it collided with a transmission wire and then fell into the Mississippi River near Lomax, Illinois. The Airline Transport certificated pilot and pilot-rated passenger aboard received minor injuries. The flight operated under 14 CFR Part 91 in visual meteorological conditions. The pilot reported that he and the airplane owner/passenger had departed Grove, Oklahoma about 1230 en route to Moline, Illinois. While flying along the Mississippi River, the airplane collided with unseen and unmarked power lines. The airplane subsequently went into the river, and the pilot and passenger exited the airplane and were picked up by a boater. According to the State Trooper who interviewed the pilots shortly after the accident, they said words to the effect that they were flying along the river, just having fun and waving at people when they struck the wire. A power company representative said the height of the two power poles supporting the power line was approximately 60 feet; he said the height of the power line the airplane struck was approximately 45-50 feet.