Accident Overview
A pilot reported that an airplane experienced a loss of brake pressure while taxiing for takeoff, resulting in a collision with terrain and the aircraft nosing over. According to the pilot's statement, the brakes did not function when applied to slow the airplane for a turn around after back taxiing on the runway. The airplane subsequently traveled off the side of the runway, continued downhill, and entered a ditch where it rolled onto its right wing.
Pre-Flight Brake Function
The pilot noted that the parking brake had been applied during fueling and operated correctly at that time, as well as during the engine run-up. No brake fluid was observed on the hangar floor where the airplane was stored, nor along the taxi route used by the airplane.
Brake System Examination
An examination of the master brake cylinder was conducted. The cylinder was disassembled and appeared to be in working order with no leaks detected.
Airworthiness Directive Placard
The airplane was placarded in accordance with Airworthiness Directive 85-02-05 R1. The placard stated: "NO BRAKING WILL OCCUR IF AIRCRAFT BRAKES ARE APPLIED WHILE PARKING BRAKE HANDLE IS PULLED AND HELD."