On September 7, 1996, at 1341 hours Pacific daylight time, a Piper PA-28R-200, N41331, collided with a runway marker while on a go-around at Oxnard Airport, Oxnard, California. The aircraft sustained substantial damage; however, neither the flight instructor nor his private pilot student was injured. The aircraft was being operated as an instructional flight by Sun-Air Aviation when the accident occurred. The flight originated in Camarillo about 1215. Visual meteorological conditions prevailed at the time and no flight plan was filed. The operator reported that the instructor and the student were performing touch-and-go landings at the Oxnard Airport. On the eighth touch-and-go approach, the student was high, so the instructor asked him to slip the aircraft for a no flap landing. The student performed the slip with full control deflection; however, the instructor noticed that as he crossed the runway threshold, he was aligned with the right edge of the runway. At the same time, he also noticed the student was allowing the airspeed to decay, and his rate of sink to continue unabated. The instructor took the controls when a collision with a runway marker appeared imminent, and was in the process of a go-around when they both felt a bump that they thought was a hard landing. The Oxnard tower then advised the instructor of the collision. The aircraft did not display any adverse flight characteristics so they returned to the Camarillo airport where they landed without further incident. A postaccident inspection revealed damage to the right wing main spar and four ribs. A 10-inch-wide gash was observed in the lower surface of the wing, as well as skin wrinkling in the surrounding area. The Oxnard airport manager reported that the 4,000-foot runway remaining marker had been struck by an aircraft. The runway is 5,950 feet long and 100 feet wide.