Brake Fire. Having carried out the normal pre-flight checks the pilot released the parking brake by fully depressing the brake pedals prior to taxi. The aircraft was taxied to the threshold of Runway 05, a distance of nearly 2 nm, which took approximately 10 minutes. During this time the engine was running at 1000-1200 rpm and the brakes were rarely operated. Just before arriving at the holding point the pilot noticed dust - like smoke coming from the area of the left wheel, the volume of which rapidly increased as the aircraft was brought to a halt.