On December 9, 2013 about 1500 mountain standard time, an Aviat Aircraft Pitts S2-C airplane, N44HV, was substantially damaged following a loss of control during landing at Chandler Municipal Airport, Chandler, Arizona. The flight instructor and private pilot receiving instruction were not injured. The airplane was owned by Arizona Pitts Leasing and operated by Chandler Air Service Inc., Chandler, Arizona, under the provisions of 14 Code of Federal Regulations Part 91 as an instructional flight. Visual meteorological conditions prevailed, and no flight plan was filed for the local instructional flight. The flight instructor reported that he and the private pilot were practicing aerobatic maneuvers and had returned back to the airport to practice touch-and-go landings. On the third touch-and-go landing the airplane drifted to the right side of the runway just prior to touching down. The flight instructor took over the controls and executed a go-around. During the go-around the flight instructor felt a slight buffet and on the flight back to the airport, noticed some damage to the lower right wingtip. After landing, the flight instructor realized that the airplane's right wing struck a runway identifier sign on the previous touch-and-go landing. Examination of the airplane was conducted by a Federal Aviation Administration inspector and revealed about a 12-inch-long section of the outboard aft spar separated from the wing. The outboard end of the aileron to the outboard hinge was bent and distorted rearward from its original position.