One issue with the Europa's drains is: how much fuel must be drawn to ensure
that one is sampling what is in the tank?
Most tank drains are immediately below the tank so draining an ounce or two
will determine whether there is water in that tank. The most common fuel
samplers hold about 1.5 ounces although those like the GATS hold considerably
more.
On the Europa, the drain lines have a significant volume so one may need to
drain 3 ounces or more to ensure that the line has been purged and the
contents of the tank are being examined. Further, it is unclear whether this
can be done in consecutive 1.5 ounce samples since given the up and down run
---From tank to drain, water could conceivably drift back toward the tank
between samples.
One thought for the tri-gear drain system would be to not install the pickup
tube which goes to the back of the tank since the low point in this instance
is at the front of the tank. Then, rotate F09 so that the finger strainer is
uppermost which will put the drain outlet below it with the aircraft level.
The drain could be installed in the inspection window if desired although
this may be difficult to access. A drawback to this approach is that the
unusable fuel will be increased somewhat due to the slightly higher position
of the pickup.
Clearly, to understand how well the drain system works one would need to run
a number of experiments. Guess that's why it's called Experimental Aviation.
The required experiments would be easy to run given an uninstalled tank and
a little plastic tubing. But its hard to get anyone with an operating
airplane to pour water into the tank deliberately.
It would be most interesting if Europa would share their results from testing
of these fuel drains.
John A044
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