O-RING SEALS By Wilton Strickland
Before I was commissioned via USAF Officer Candidate School in 1960, I was a maintenance crew chief on B-47E's at Lincoln AFB, NE, for about 2½ years. During the 1959 Christmas holiday period, the entire unit of 45 B-47's and about 20 KC-97's "stood down" for a week or so - there was no flying, and no maintenance was performed on the aircraft during this time - everyone in the wing, except certain "essential" personnel was off duty for the entire several days. Temperature during this time was about 0° to 10° F. When we returned to work, all of the airplanes were thoroughly "cold-soaked" - systems on most of them had not been operated for well over a week. This caused rubber seals to shrink and become hard, leading to a special problem for fuel booster pumps. In the bottom of each fuel tank, were electrically-operated booster pumps used to send fuel from the tanks to the engines or to transfer fuel from tank to tank. There were several tanks on the aircraft, and each tank had at least two pumps, some had four pumps for a total of 28 of these pumps on the aircraft. These pumps were notorious for leaking, even during normal day-to-day flying and maintenance conditions. On the very cold January morning when we returned to work after the week or so off, all of us crew chiefs applied power from the external power carts (MD-3's), started running the fuel booster pumps and checking them for leaks in the usual places. Almost immediately, there was a big backlog of B-47's waiting to be towed to the refueling pits to have all of their fuel removed to facilitate removing and replacing many fuel booster pumps. I found several of the pumps on my aircraft leaking, too, but I did not think it was alarming enough to warrant mass pump replacements. I was by myself again that day and had no help for changing a bunch of pumps that I thought was likely unnecessary, anyway. I just continued to wipe the small bit of leakage away at each pump as necessary and kept running the pumps, hoping that the O-ring seals would warm up and seal themselves. I just kept quiet about any leakage and kept making the rounds to all of the pumps for several hours. Gradually the number of leaks began to diminish until I had no leaks at all. Most of the other aircraft in my unit were still being de-fueled and getting pumps replaced when I closed up and left at the end of the day. My aircraft had not moved from its parking space all day. I've often wondered why nobody seemed concerned that I had reported no leaks all day while most other crew chiefs were reporting many. About 25 years later, on the very cold morning in 1985, when I heard a news report that the temperature at Cape Canaveral was significantly lower than that experienced by any space shuttle launch before, I thought of those leaking fuel pump O-ring seals on that cold January morning in 1960 and even said aloud to myself, "Uh-oh, that could be trouble. They should not launch." You know the rest of the story.
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