On October 7, 2002, about 0830 mountain standard time, an amateur-built Kline KSE5A airplane, N589D, veered off runway 21, encountered a ditch, and nosed over during the takeoff ground roll at Sedona Airport (SEZ), Sedona, Arizona. The pilot/owner was operating the airplane under the provisions of 14 CFR Part 91. The private pilot, the sole occupant, was not injured; the airplane sustained substantial damage. The personal cross-country flight was originating from Sedona, en route to Rimrock, Arizona. Day visual meteorological conditions prevailed, and no flight plan had been filed. In a written statement, the pilot reported that he began his takeoff and applied full power about 150 feet down runway 21. The airplane veered to the left and proceeded off the runway. He reduced the power, but the airplane continued for about 100 feet until it encountered a ditch. The airplane nosed over and came to rest inverted. The pilot said the automated weather observation system (AWOS) at the airport reported wind at the time of the accident as variable from 250 degrees at 8 knots. Another pilot, who was on the airport at the time of the accident, told the accident pilot that the AWOS also reported wind gusts to 17 knots. During a telephone conversation with the National Transportation Safety Board investigator-in-charge, the pilot attributed the accident to his left wheel brake locking. The pilot stated that as the airplane veered off the runway, he applied brakes and felt the left wheel lock. The left wheel was a motorcycle wheel, and, according to the pilot, was "only meant to go on the right side unless otherwise adapted." Following the accident, the pilot modified the wheel with a spring to prevent it from locking.