reply to post by Aloysius the Gaul
Commonly, a brand named product called "Prist". Abvout 10 to 15% by volume.
But, as smurfy
noted, large modern jets (and many other, smaller jets) don't need such additives. The fuel is heated at points, near
the engine, just as it is being routed to the Fuel Control Unit. How?
, you may ask? Simple. A fuel-oil heat exchanger. Does two
things. First, since oil needs to be constantly cooled, the fuel helps with that (additionally, ambient airfow will radiate excess heat as well).
And in return, the fuel is heated....a win/win for simplicity in design. At that point, any ice that may have been present is melted to water, and
separated downstream of the heat exchanger.
Airplanes are not dispatched if there is a fault in these systems....about the most common occurrence of failure is when cracks form, allowing
leakage....the fuel there is at a higher pressure, so it enters the confined oil system loop....this is indicated first, to the crew, by the odd
increase in oil quantity indications. Also, fuel and/or oil leaks overboard may occur too.....oil leak , obviously, by an alarming quantity decrease,
along with low pressure warnings. Fuel leaks are less obvious, usually, and will be caught by the disagreement with fuel flows as measured, and
resulting fuel quantity. Automatically monitored, nowadays...before that computerization, was done the old-fashioned way, with simple math at
regularly scheduled checkpoints, usually about an hour or so apart. Also, by cross-checking against the flight plan estimated predictions, since that
is included in the printouts.
Oil and fuel leaks are very, very rare in modern engines.....reliability standards have increased dramatically since the early 1960s....though the
basic design principles of systems are the same. Better engineering tolerances.....