 All F-84Fs were grounded in November 1971, after a 170th pilot was killed when his plane lost a wing during exercises at the Hardwood Gunnery Range in Findley, Wisconsin.The accident was caused by the "milkbone" joining bolt in the main wing which had been weakened by years of flying and failed in-flight.All RF-84F aircraft were immediately grounded after inspections of other F-84Fs in the Air National Guard found the same issue affected many other aircraft.