On October 7, at 1235 central standard time, a Beech C90A, N200HV, operated by Hy-Vee Food Stores, Inc., was substantially damaged when it was struck by a United Airlines lavatory truck, LT-411. The airplane was taxiing outbound on taxiway Delta at O'Hare International Airport, Chicago, Illinois, when the truck hit the right engine and the nose of the airplane. The airline transport pilot reported no injuries to himself or the copilot. Two passengers received no injuries and one passenger received minor injuries. The driver of the truck received minor injuries. The 14 CFR Part 91 flight had filed an instrument flight plan from O'Hare International Airport, with Des Moines International Airport, Des Moines, Iowa, as the intended destination. The pilot reported that the airplane's taxi instructions were to taxi from the Signature ramp down Delta taxiway to D1, turn north on Bravo taxiway, cross the Bravo bridge to runway 32R. He reported that while the airplane was taxiing through a Delta taxiway intersection, a United Airlines lavatory truck "slammed in the side of our right engine and right prop." The airplane was pushed approximately 10 feet off of the taxiway centerline, and the left main tire came off the rim of the wheel. The copilot of the airplane reported that the "lavatory servicing truck crashed into our airplane from the right, hitting our right engine and prop." The O'Hare International Airport Law Enforcement report indicated that the collision between the airplane and lavatory truck occurred at the D-3 intersection. The airplane was taxiing westbound and was hit by the lavatory truck which was proceeding southbound. The O'Hare Law Enforcement issued a violation to the driver of the truck for failing to give-way to an aircraft. The O'Hare Airport Department of Aviation Special Police reported that, "According to witnesses, the driver of the truck didn't observe the aircraft until the aircraft was a few yards away. The truck driver tried to swerve to avoid the aircraft, but it was to late." The driver of the truck reported that she had "stopped at the stop sign painted on the ground on the access road, didn't see any airplanes. Thought it was like a Saturday-no planes. When I started driving, like 2 mph, something hit me on my side of the vehicle-don't know what it was and I don't know anything after that." The United Airlines lavatory truck, number LT411, had undergone a "B" maintenance check on September 12, 1997. The United Airlines O'Hare Operating Procedures for motor vehicles stated in the section for Yielding the Right-of-Way, "No person shall operate a motor vehicle unless he yields the right-of-way to aircraft in motion. TAXIING AIRCRAFT ALWAYS HAVE THE RIGHT-OF-WAY." The O'Hare Ground Vehicle Operating Regulations state, "No Person operating a Ground Vehicle shall cross taxiways without bringing the vehicle to a complete stop and observing ground airplane traffic in all directions. TAXIING AIRCRAFT ALWAYS HAVE THE RIGHT-OF WAY."