On May 18, 2016, about 1520 eastern daylight time, a tail-wheel equipped North American AT-6D, N757LF, departed the left side of the runway while landing at Mason Jewett Field Airport (TEW), Mason, Michigan. The airplane sustained substantial damage to the left-wing structure. The commercial pilot, the sole occupant, was not injured. The airplane was registered to and operated by a private individual under the provisions of Title 14 Code of Federal Regulations Part 91 as a personal flight. Day visual meteorological conditions prevailed for the flight, and no flight plan was filed. The flight originated from the Brooks Field Airport (RMY), Marshall, Michigan, at 1455 was destined for TEW. The pilot reported that he checked the automated weather report at TEW while about 10 miles from the airport, and again on short final for landing. He said both times the weather report stated the winds were from 090º at 6 kts, favoring runway 10. The airplane touched down normally on runway 10, prior to the 1,000-ft markers on the runway. On rollout, prior to the halfway point of 2,000 ft, there was a wind shift, and he encountered a gust of wind in a "northerly direction." He added aileron flight control input to "counteract the wind shift" but the airplane "veered/looped" to the left. The airplane exited the left side of the runway and came to rest in a drainage ditch near the runway. At 1514, the automated weather observation system (AWOS) at TEW reported wind from 040º at 5 kts, visibility 10 miles, scattered clouds at 6,500 ft, temperature 17ºC, dew point 2ºC, and barometric altimeter setting 30.19 inches of mercury. At 1534, the AWOS at TEW reported wind from 010º at 5 kts, gusting 14 kts, visibility 10 miles, scattered clouds at 6,500 ft, temperature 16ºC, dew point 2ºC, and barometric altimeter setting 30.19 inches of mercury. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation. He stated the accident flight was his 2nd hour of flight time in the accident airplane. He was "still getting a feel for the airplane, especially how it reacted in different wind conditions." He said more time in the accident airplane would have helped to prevent the accident.