On September 22, 2000, about 0220 mountain daylight time (MDT), a Beech B99, N99TH, sustained substantial damage during landing on runway 29, at Missoula International Airport, Missoula, Montana. The airplane was operated by Alpine Air of Provo, Utah, as a domestic cargo flight under the provisions of Title 14, Part CFR 135, when the accident occurred. The commercial pilot, and the airline employee passenger were not injured. Visual meteorological conditions prevailed and an instrument flight plan was filed. The flight originated at Billings, Montana, about 0100 MDT. In a written statement, the pilot reported that the airplane touched down on the centerline of runway 29. He stated that when he applied wheel brakes, "the right brake locked up" and the airplane immediately veered to the right. The pilot applied left brake, left rudder and reversed the left propeller, however, the airplane continued to the right. The airplane collided with a taxiway light and runway marker before departing the right side of the runway. The airplane sustained substantial damage to the fuselage. A skid mark that coincides with the airplanes right main landing gear was noted on the landing runway. The skid mark originated near the runway centerline and continues to the point where the airplane left the runway. Post-accident photographs of the airplane, taken on the night of the accident, revealed ice and snow deposits on the cargo pod, right lower engine nacelle, main landing gear strut and right dual brake assembly. The landing runway in Missoula was dry, however, the departure airport at Billings was contaminated with approximately 6 inches of snow and slush. On September 22, FAA personnel from the Helena, Montana, Flight Standards District Office, inspected the airplane and reported that there was no evidence of system mechanical malfunction that would have resulted in a brake failure (Report attached).