I've never encountered water in a/c fuel either. However, I did in an
auto once and I wonder how a water separator would have handled it.

I filled up an almost empty '95 Caravan with fuel that had a great deal
of water in it. The van died before turning out of the station. After
damning my luck at a breakdown on a raining winter evening 100s of miles
from home, we looked for a meal and a hotel. Then I noticed that there
were several people milling about the interstate exit, on foot! No one
walks anywhere in January at an interstate exit. Further observation
found that a number of cars were parked irregularly all over the place.

I put 2 and 2 together and immediately went in the station and suggested
that water was in the fuel and that the pumps needed to be closed. The
confused teenager handling the desk didn't know what to do so insisted
she call the owners and I went out and hung signs closing the station.

Anyway, I concluded that the problem resulted from semi-melted ice all
over the parking lot. They were damming up the cold rain and the water
ran into the tanks during a fill or otherwise overcame whatever
protection is normally in place. Ever seen 3 guys chain smoke while
draining fuel tanks into 55 gallon drums.

How would water sparators work with an 'enormous' quantity of water in
the fuel?

Jose wrote:
Why is it that devices to separate water from fuel are quite
common cars (my F-350 truck has one), but such a device, which
could save lives in an airplane, is not offered for airplanes ?
Even as a retrofit ?


To this and other similar questions, the general answer is weight, cost,
and reliability.

Weight - all the gadgets and gizmos weigh something, and this gets
removed from your useful load. If all the safety features people wanted
were included, the airplane would never fly. I guess that would be
pretty safe. Cars don't have to fly, so they can be as heavy as it
takes - a few pounds here and there don't really make a difference. But
in the air they do.

Cost - mainly certification cost, since any newfangled gizmo has to go
through the FAA wringer to ensure that there are no unexpected
surprises. Whether this is actually effective or not is subject to
debate (witness the homebuilt arena) but it is necessary.

Reliability - it's another gizmo to go TU, with unpleasant side effects.
Cars can pull over when they break. Planes can't. In the case of
this particular item (fuel/water separators), it would still not relieve
the pilot of the necessity to check for water in the gas, since we all
know that things that "shouldn't" happen, do anyway.

Jose