Before landing the pilot reported that brake pressure was available on both brakes. He stated that the aircraft touched down 400 metres after the threshold of the 1000 metre strip and when the brakes were applied no pedal pressure could be obtained. The aircraft overran the strip and collided with a ditch. A small hole had developed in the left brake line due to chaffing action against loosely clamped mounting bracket. No defect could be found with the right hand brake system. By the time the pilot realised that a problem existed with the braking system, he considered that there was insufficient strip remaining to carry out a go around.
