If a tomahawk had an engine failure due to water at about 3000ft. it would take about 6 mins for it to glide back to earth.
most toma's burn about 20 lts an hour. or 1 lt per 3 min's.
so, by my maths, you would need to have 2 lts of water in the tanks for the plane to crash (force land) due to water in the fuel.
I've got about 400 hrs on pa38's. and never have i had more than i few bubbles in the bottom of the normal tester.
I think a far simpler method of preventing engine failures due to water is by conventional tools, such as a fuel tester. I think if you also research what would be required to get such a devise approved by the manufacture and the likes of the CAA/FAA, you will find, financially it makes no sense.
remember the basic's of design -
K.I.S.S. = keep it simple stupid!
Also, for your project. check the POH (pilot op handbook) im sure there is a blueprint in there!
How about inventing a fuel tester which you can use with out getting covered by bloody avgas!
