On June 24, 2005, at 0756 mountain daylight time, a Rockwell International S-2R, N4865X, registered to a private individual, and operated by Nyssa Ag Service as a 14 CFR Part 137 aerial application flight, experienced a loss of engine power while returning to Mountain Home Municipal Airport, Mountain Home, Idaho. During the emergency off airport landing, the aircraft collided with a heavy truck traveling on a highway. Visual meteorological conditions prevailed at the time and no flight plan was filed for the local flight. The aircraft was substantially damaged and the commercial pilot, the sole occupant, was not injured. The driver of the truck was not injured. The pilot reported to Federal Aviation Administration Inspectors from the Boise, Idaho, Flight Standards District Office, who responded to the accident site, that he had just dumped a load of pesticide and was returning to the airport, knowing that he was low on fuel. About 1/2 mile short of the runway, the engine lost power due to fuel exhaustion. During the forced landing on a highway, he overtook a heavy truck during the landing roll. The right wing came in contact with the truck and the aircraft subsequently traveled off the north side of the road and down an embankment before coming to rest.