On February 16, 2005, about 1720 mountain standard time, a Piper PA-28-161, N80565, veered off the runway and collided with a taxiway sign at Chandler, Arizona. Chandler Air Service, Inc., was operating the airplane under the provisions of 14 CFR Part 91. The student, the sole occupant, was not injured; the airplane sustained substantial damage. The local instructional flight departed Chandler about 1620. Visual meteorological conditions prevailed, and no flight plan had been filed. The pilot submitted a Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2). He stated that he departed Chandler Municipal and remained in the south practice area for approximately 35 minutes. He then returned to Chandler airport to perform touch-and-go landings. After completing six touch-and-go's he performed a full stop landing on runway 22 right to terminate the lesson. The landing was normal, but shortly after all three wheels were down, he applied brake, which caused the airplane to skid. The airplane started a skid and he attempted to straighten the airplane out. The airplane veered to the right-hand side of the runway where it came in contract with a taxiway sign, which spun the airplane causing damage to the right wing. The pilot stated that the airplane and engine had no mechanical failures or malfunctions during the flight.