On February 19, 2014, about 1415 eastern standard time, a Piper J3C-65, N9026N, operated by a private individual, was substantially damaged during a collision with terrain, following a loss of control while maneuvering at low altitude over Macon Downtown Airport (MAC), Macon, Georgia. The airline transport pilot and passenger were seriously injured. The personal flight was conducted under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed and no flight plan was filed for the planned local flight. The pilot reported that he was seriously injured in the accident and did not recall the accident sequence. Two witnesses were standing near a hangar at the airport and watched the accident airplane perform touch-and-go landings. They reported that the airplane lifted off about halfway down runway 28 and began a right turn to a crosswind leg of the airport traffic pattern, about 100 feet above ground level (agl). As the airplane began the right turn, a gust of wind struck the airplane. One of the witnesses added that the wind gust increased the bank angle from approximately 30 degrees to 90 degrees and the forward speed slowed. The airplane then stalled, rolled right, and descended uncontrolled into a grassy area adjacent to the runway. Examination of the wreckage by a Federal Aviation Administration (FAA) inspector did not reveal any preimpact mechanical malfunctions. He confirmed flight control continuity from the cockpit controls to their respective control surfaces. He was able to rotate the propeller about 90 degrees. Impact damage to the cylinders precluded him from rotating the propeller through 360 degrees. The inspector further stated that although the fuel tank was compromised, he observed evidence of fuel at the accident site. Middle Georgia Regional Airport (MCN), Macon, Georgia was located about 8 miles southwest of the accident site. The recorded weather at MCN, at 1353, included: wind from 280 degrees at 11 knots, gusting to 20 knots; broken ceiling at 3,300 feet, and visibility 10 miles. Review of the FAA Airplane Flying Handbook (FAA-H-8083-3A) revealed: "…On the departure leg after takeoff, the pilot should continue climbing straight ahead, and, if remaining in the traffic pattern, commence a turn to the crosswind leg beyond the departure end of the runway within 300 feet of pattern altitude." Traffic pattern altitudes are usually 1,000 feet agl.