Incident Overview
A pilot reported that after touchdown, he applied left brake pedal pressure to help maintain directional control as the aircraft slowed. Upon releasing the pedal, it remained depressed with the brake still activated. The pilot attempted to counteract the unbalanced braking by applying right brake pressure and using the rudder. Initially, these corrective actions allowed some directional control, but as the aircraft decelerated, their effectiveness diminished. The aircraft eventually departed the left side of the runway and ground looped.
Post-Accident Examination
Following the incident, an examination by the operator revealed that the left brake master cylinder had malfunctioned. Specifically, the cylinder would bind when the pedal was depressed, preventing it from returning to its neutral position and keeping the brake applied. This mechanical failure caused the persistent brake application observed by the pilot.
Sequence of Events
- The pilot applied left brake after touchdown as part of normal directional control.
- Upon release, the left brake pedal remained depressed, and the braking continued.
- The pilot managed partial control using right brake and rudder inputs.
- As the aircraft slowed, the ability to maintain directional control decreased.
- The aircraft ran off the left side of the runway and executed a ground loop.
The incident highlights a mechanical failure in the braking system that compromised the pilot's ability to steer the aircraft after landing.