Light Sport Aircraft
Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor; Flight Crew Multiengine
Flight Crew Last 90 Days 5; Flight Crew Total 22000
Human-Machine Interface; Training / Qualification
Aircraft Equipment Problem Less Severe; Ground Event / Encounter Loss Of Aircraft Control; Ground Excursion Runway
Aircraft Aircraft Damaged
Human Factors; Aircraft
Was taxiing to acquire the feel of new Light Sport Aircraft that I was operating. Made multiple taxi events including turns right and left to get the feel of the aircraft at different speeds and turning radius. Aircraft had 1 brake handle on the control stick that sends brake action to both main wheels simultaneously. This was a new method for braking I had never used. After several runs of a few hundred feet I elected to increase speed slightly and observe the effect in the effectiveness of the steering mechanism. I intended to remain well below liftoff speed during all taxi operations. During this particular taxi run the nose wheel began to lift off the asphalt. I promptly squeezed the brake handle to bring the aircraft's nose back to the asphalt. I was sitting in the left seat and at 230 lbs. there was much more weight on the left main tire than the Right due to seat position Left of the center of gravity. Since the brake handle sends equal brake pressure to both main tires the left main effectively took most of the braking action due to the most weight on the left main gear. This immediately took the aircraft 45 left turn and the aircraft left the runway asphalt and into the grass area adjacent to the runway. The aircraft rolled into a low ditch area close to the runway which had a concrete drainage form at the end of the drain tile that crossed under the taxiway. The airplane came to a stop in the drainage area adjacent to the concrete structure; damaging parts of the nose gear structure and portions of the wing leading edge. No injuries occurred and minimal damage to the aircraft due to the low speed at the time the aircraft exited the runway. Take away lessons I believe are:Should have had someone in the right seat to balance the weight load for taxi and braking events. Should have brought an instructor or someone familiar with this type of aircraft with me during taxi runs. Should have familiarized myself further on the braking action geometry before doing the taxi runs. Lesson learned- Just because it looks like very simple aircraft systems doesn't mean they are simple in all taxi/weight/speed regimes.
Light Sport pilot reported taxiing and losing control and exiting runway into grass.