QUOTE:
You've probably heard the SR-71 is a severe leaker, and I'll try to put this into perspective. Once LN2 is serviced a few hours prior to launch, the
fuel system becomes pressurized, and that's when the real leaks start. Normally, about five or six steady fuel leaks (about the width of a drinking
straw) show up coming from both inboard wings, falling about six feet to the ground. The entire bottom of the fuselage becomes wet, and starts
dripping onto the hanger floor. Some puddling starts to accumulate on top of the inboard wings, and at times runs off the wing onto the floor. In some
bad leakers, fountains can be seen spraying upward from the top of the inboard wings, ranging anywhere from two inches to three feet in height.
Usually, the really bad leaks occur when the aircraft is getting close to being sent to the Depot for an overhaul. How much fuel is actually lost
prior to flight? It was a common practice to refuel the aircraft about four or five hours prior to flight. It was also standard to place about four to
seven hundred pounds of JP-7 extra in the tanks to allow for this leakage. That's a loss of about one hundred pounds or sixteen gallons per hour. And
folks, that's just for a standard fuel load. At times, due to lack of tankers, we would put considerably more fuel onboard, and launch her on a
"rocket ride". When we did this, you could basically double the amount of leaks I've described. Why all the leaks? High temperature fuel sealant
was especially designed for the SR-71, and there's no other substance known in existence to replace it. Once the aircraft is as cruise speeds, it
tends to seal itself. The leaks I've spoken of do not jeopardize the safety of the aircraft, due to the high flash point of JP-7. In fact, a lit
match thrown into it would just go out. Up until the late 80's, the fuel leaked was simply washed out of the hanger after the launch, and went into
the ground. Due to environmental laws towards the end of the program, we started to catch the fuel in drip pans, dispose of it properly, and vacuum
the residual from the floor. You could always pick out the guys who had participated in a launch. They smelled like JP-7, there hair was sticky
looking, and fuel stains covered their uniforms. Many guys wore rain suits to eliminate this problem. Believe it or not, a half can of Coke added to
the wash removed all the stains and smells from the clothing.
www.blackbirds.net... 
