WPR12LA074

According to the pilot, he performed a brake check and used the brakes numerous times while taxiing to the run-up area; however, as he approached the run-up area, the brakes failed, and the airplane continued to roll forward. He decided to steer the airplane off the taxiway surface and not risk an excursion onto the active runway. The airplane veered off the paved surface onto unprepared desert terrain, and the airplane continued to accelerate. The pilot attempted to shut down the engine with the ignition switch, but was unable to. He said that normal engine shut down is accomplished using two magneto switches on the instrument panel and not the ignition switch. The airplane then struck a boundary fence. Postaccident examination revealed that the left wheel brake assembly was damaged by impact forces consistent with the airplane’s collision with the fence. The examination of the brake system for fluid leaks and functionality did not disclose any evidence of a preexisting mechanical malfunction that would have precluded normal operation. It is likely that, if the pilot had shut down the engine before the airplane departed the taxiway surface, he would have been able to stop in time to avoid colliding with the airport boundary fence.

On January 6, 2012, at 0800 mountain standard time, a Czech Sportplanes Dynamic WT-9, N247DY, collided with a fence following an excursion off the taxiway at the Glendale, Arizona, airport. The aircraft was operated by the pilot for a local area personal flight conducted under the provisions of 14 CFR Part 91 of the Federal Aviation Regulations. Visual meteorological conditions prevailed. The airplane sustained substantial damage and the pilot was not injured. While taxing to the run-up area the pilot performed a brake check and used the brakes numerous times while taxing. The pilot said that the brakes failed as he approached the run-up area and the airplane continued to roll forward. He decided to steer the airplane off the taxiway surface, and not risk an excursion onto the active runway. Once off the paved surface and onto unprepared desert terrain, the airplane continued to accelerate. The pilot attempted to shut down the engine with the ignition switch but the engine remained operating. The airplane veered to the left, continued to proceed over the unprepared terrain, and impacted the airport boundary chain link fence. The pilot said that normal engine shut down is accomplished using two magneto switches on the instrument panel and that the ignition switch does not shut down the engine. NTSB investigators examined the airplane and found the left wheel brake assembly damaged by impact forces consistent with the airplane’s collision with the chain link fence. The brake system was inspected for fluid leaks and functionality. No preexisting condition was identified that would have precluded the normal operation of the brake system.