I flew a Sabre (F-86 fighter) as a chase plane on those missions which called for me to fly alongside an aircraft being tested. One day, I flew up into the Sierra Nevada mountains to check on a favorite fishing lake. A buddy of mine named Dave Sheltren lived at the edge of the lake, and I came across low to buzz his place, did a slow roll over his house, when suddenly my aileron locked. It was a hairy moment, flying about 150 feet off the ground upside down. But as soon as I let off on the g's, pushing up the nose (actually causing the airplane to head more toward the ground) the aileron unlocked. Very strange. I climbed to 15,000 feet, where it was safer to try it again, and each time I performed that rolling maneuver, the aileron locked. I figured that somehow the wings were bending under stress and locking the aileron. I called General Boyd as soon as I landed and told him I thought I knew how those crashes (the Air Force had lost 3 or 4 pilots for no apparent reasons when their planes crashed while doing rolls down on the deck) occurred, but not why.
The General sent inspectors to take apart my Sabre's wings. They found that a bolt on the aileron cylinder was installed upside down. Crew chiefs in every Sabre squadron were ordered to inspect their airplanes' wings for that upside-down bolt, while an inspection team went to the North American plant and found the culprit. An older man on the assembly line had ignored instructions about how to insert that bolt because, by golly, he knew that bolts were supposed to be placed head up, not head down. Nobody told him how many pilots were killed by his assuming he didn't need to follow instructions.
