On April 11, 2010, at 2030 eastern daylight time, a Piper PA-28-180 single-engine airplane, N3470R, sustained substantial damage during landing at Three Rivers Municipal Dr. Haines Airport, Three Rivers, Michigan. The flight instructor and student pilot were not injured. The airplane was registered to and operated by a private individual. Visual meteorological conditions prevailed, and a flight plan was not filed for the Title 14 Code of Federal Regulations Part 91 instructional flight. The local flight departed from Three Rivers at 1940. According to the flight instructor, he and the student pilot were practicing touch and go landings. During the landing previous to the accident, the instructor reported that the landing "was not very good." The airplane touched down on the centerline; however, the student touched the left brake, which caused the airplane to divert to the left. The instructor corrected and they taxied back for another takeoff. During the accident landing after touchdown, the airplane veered to the left and the flight instructor attempted to correct to the right thinking the student applied the left brake again. However, the airplane continued to veer to the left and the right wing struck the terrain. The airplane continued off the runway and came to rest in a field. Examination of the airplane revealed the left aft spar was bent and fractured, the left main landing gear separated, and the left main landing gear torque link was fractured. The torque link was retained and sent to the NTSB Materials Laboratory for further examination. NTSB Materials Laboratory examination of the torque link revealed the fracture face contained crack arrest marks typical of fatigue cracking that emanated from multiple origins at the surface of the wall on both sides of the link. On one side of the link, the fatigue crack extended through approximately 40 percent of the wall and on the other side, the fatigue crack extended through approximately 30 percent of the wall. The fatigue origin areas contained no evidence of gouge or corrosion damage. Hardness testing of the material produced values greater than the minimum hardness value.