The Incident
During a pre-takeoff taxi, the pilot of a tailwheel-equipped airplane completed before-takeoff checks and began moving onto the runway. The pilot added power and initiated a left turn to align the airplane with the runway. While attempting to stop the turn, the right brake failed, causing the airplane to ground loop. During the ground loop, the right wing struck the gravel runway surface.
Damage
The airplane sustained substantial damage to the right wing and aileron.
Investigation
An examination of the right brake master cylinder revealed that the right brake would not hold pressure. The O-ring within the master cylinder had dried out, allowing brake fluid to leak past, which resulted in the brake failure.