On December 20, 2017, about 1530 central standard time, a Piper PA-12 airplane, N47FP, sustained substantial damage following a runway excursion upon landing at the Texas Gulf Coast Regional Airport (LBX), Angleton, Texas. The pilot and one passenger were not injured. Visual meteorological conditions prevailed throughout the area and flight plan was not filed. The airplane was registered to a private individual and the personal flight was being conducted under the provisions of Title 14 Code of Federal Regulations Part 91. The flight originated from the Flying Tiger Airport (81D), Angleton, Texas, about 1515.

According to the pilot, after an uneventful flight from 81D, the pilot checked the weather for landing at LBX and conducted a visual pattern and approach to runway 17. The winds were from 220° at 6 knots which would yield about a 5 knot right-to-left crosswind component. The landing was on airspeed, on runway centerline, and in the touchdown zone. After lowering the left wheel to the ground, the aircraft immediately and uncontrollably veered sharply to the left. The pilot applied full right rudder and immediately held the stick full right and aft to keep the aircraft from ground looping or cartwheeling. The pilot was unable to regain directional control of the aircraft and departed the runway to the left and proceeded to impact two of the four Precision Approach Path Indicator (PAPI) lights for runway 17. The propeller hit a PAPI light and the aircraft continued and came to a stop in the grass about 50-100 feet off the runway. The pilot immediately suspected that a brake had somehow locked on the left main wheel. Braking marks on the runway and grass correlated to the left main landing gear tire as it passed from the runway surface onto the grass. The airplane was towed to a hangar for examination.

After an examination by a Federal Aviation Administration inspector and a mechanic, no anomalies were discovered with the left brake assembly. The pilot reported on National Transportation Safety Board accident report form that he thought that the left brake was somehow activated upon landing, and knew that his feet were nowhere near the brakes as he was planning a touch and go. After inspection of the brakes, the pilot stated that he believed that the passenger could have inadvertently had his foot on the brake pedal during the landing rollout.The pilot also stated that he had thoroughly briefed his passenger prior to the flight regarding the basic use of flight controls, emergency procedures, and flight plan.