On October 21, 2001, about 0908 hours mountain standard time, a Bellanca 7ECA, N2987Z, experienced an on-ground collision with a Mooney M20A, N6049X, at the Chandler Municipal Airport, Chandler, Arizona. At the time of the collision, the Bellanca was starting to taxi for takeoff, and the Mooney was standing nearby in the run-up area. Visual meteorological conditions prevailed. The Bellanca had been rented from PBJ Aircraft, Inc., at the Chandler Municipal Airport. The Mooney was owned by its pilot. The Bellanca sustained minor propeller damage, and the Mooney's wing was substantially damaged. Neither the private pilot in the Bellanca nor the commercial pilot in the Mooney was injured. The personal flights were operating under 14 CFR Part 91, and they were originating at the time. The Bellanca pilot reported that he had completed his engine run-up and had commenced taxiing toward runway 04L's hold short lines, located about 30 feet ahead and to his right. The Bellanca began taxiing from his heretofore stationary location, and he veered left. The pilot indicated that he attempted to correct the airplane's taxi path away from the Mooney that had been located on his left side next to him in the run-up area. The Bellanca pilot indicated that he was able to momentarily stop the left turn. However, the airplane turned left again. Despite his application of right rudder and right brake, the airplane veered left until coming into contact with the Mooney that was still standing nearby in the run-up area. The Mooney pilot reported that he was also located in the run-up area and was performing the pretakeoff check at the time of the collision. His airplane's brakes were set. He had noticed the Bellanca, which had initially been located in the run-up area to his right side, taxiing perpendicular to and in front of his position. The Bellanca turned left and then approached his airplane in a nearly head-on course until it stopped upon striking his left wing. The Federal Aviation Administration Coordinator reported that the Bellanca was subsequently examined. No evidence of any mechanical malfunctions were found with the airplane's directional control and braking system.