Originally Posted by
Dave Therhino
It takes about a minute of idle operation for the engine to flame out after closing the spar valve or LP fuel valve only (not the HP valve in the engine HMU) because that's how long it takes to suck the remaining fuel out of the fuel line between the LP valve on the rear spar and the fuel pump to the point where LP stage of the fuel pump receives excessive vapor and sends vapor to the HP pump. It takes a similar amount of time on the Boeing airplanes.
Hi Dave,
I agree as to where the fuel comes from - but my real question is: What "replaces" this fuel, in other words: what happens to the space where the fuel is taken from by the engine?
Assuming that the LP valve and the tubing between the LP valve and the HMU has no leaks, there would be a SIGNIFICANT vacuum in the lines...? Wouldn´t that trigger leaks afterwards as the tubes are designed for "outward" pressure, not an internal vacuum?
Regards, J. V.