On July 26, 1995, at 1349 central daylight time, a Cessna Citation 550, N72WC, operated by Pioneer Private Aviation Inc. of Minneapolis, Minnesota, sustained substantial damage while landing at Flying Cloud Airport, Minneapolis, Minnesota. The airplane was conducting a mechanical test flight to verify the operation of the air conditioning system when the accident occurred. The pilot and two mechanics reported no injuries. The local 14 CFR Part 91 flight operated without a flight plan in visual meteorological conditions. After completing a maintenance test flight, the pilot reported that they returned to Flying Cloud Airport for landing. The pilot allowed the mechanic, who was seated in the right seat and is a commercially certificated pilot, land the airplane. During the final approach, the pilot stated that the mechanic allowed the airplane to float too far down the runway. The pilot stated he called for a go around and then took control of the airplane for the second landing attempt. The pilot stated the second attempt was a normal landing. During the landing roll, the pilot stated he deployed the thrust reversers and stepped on the brakes but the brakes had no effect. The mechanic tried to depress his brakes, but there was also no braking action. The airplane veered off the left side of the runway and came to rest approximately 800 feet from the end of the runway. Postaccident examination found the brakes intact and in place. No hydraulic fluid was seen leaking. No abnormalities were found with the brake releases, anti-lock system, or the thrust reversers. The transducer and control valve were removed and tested. All tests were satisfactory and met manufacturer limits. The Pilot Operating Handbook for the Cessna Citation 550 states in Section III Normal Procedures, "If, during landing, a hard brake pedal - no breaking condition is encountered, operate the emergency brake system." The pilot had stated to the FAA that he did not use the emergency brake system.