On October 24, 1993, at 1714 eastern daylight time, a Cessna 140, N73003, registered to Ronald C. Thompson of Saginaw, Michigan, and operated by a private rated pilot, experienced a total loss of engine power while in cruise flight. A forced landing was conducted to a crop field. The airplane impacted the terrain on landing and sustained substantial damage. The pilot and one passenger reported no injuries. The personal 14 CFR Part 91 flight was operating in visual meteorological conditions. No flight plan was on file. The local flight departed Frankenmuth, Michigan at 1630. On initial contact the pilot-in-command stated that he might have pulled the mixture instead of the carburetor heat. An examination of the airplane subsequent to the accident did not find any mechanical anomalies which would have contributed to the accident; however the instrument panel arrangement of mixture and carburetor heat are non-standard according to modern industry accepted standards. The shape, size, and color of the knobs is the same. Verification of the function of the control is not identifiable by tactile or visual identification.