On October 29, 1997, at 1530 central standard time, a Champion 7ECA, N7505F, operated by a commercial pilot experienced a separation of the main entry door during cruise flight 9 miles east of Augusta, Kansas. Substantial damage to the right wing resulted from the door separation. Visual meteorological conditions prevailed and no flight plan was filed. The pilot and passenger were not injured. The original destination for the flight was Wichita, Kansas, but the pilot diverted to Augusta, Kansas, following the door separation. The 14 CFR Part 91 flight originated from Beaumount, Kansas, at 1500 cst. The airplane was inspected by an Inspector from the Federal Aviation Administration Wichita Flight Standards District Office who reported that the main entry door quick release hinge pins backed out of the hinges, allowing the door to separate from the airplane. The system is designed with a safety pin to secure the hinge pins in place. There was no evidence that the safety pin had been installed. The airplane owner reported that he had the door off of the airplane during the summer and had recently reinstalled it.