Re: REFLECTOR: Fuel Drains

["Al Gietzen" <alventures@email.msn.com>]

First, the assumption is being made that water will not be able to find its way down a 3/8" line that has fuel in it without flow. Has this been shown to be true?

 

 Any amount of flow would cause the water to go through the line to the sump tank.  When you add fuel to one tank; the level differential between tanks will cause flow to/through the sump tank; thereby trapping the water in the bottom of the sump.  Always fill the second tank to a level higher than the first.  In topping off, this will happen whether you like it or not unless you're filling both tanks simultaneously.  And one might expect that if water is coming from the fuel source; it would come at the start of filling.

 

You might consider taking more than one sample from the sump after refueling.  If you're still concerned; after filling fuel, startup and taxi a bit (do a figure 8); then re-check the sump drain.

 

Or maybe the easiest; go lift up on one wingtip; then the other, before checking the sump drain.  This will ensure the water gets to the tank exit, and cause some flow to get it into the sump tank.

 

That's my sample cup's worth on the subject.

 

Al Gietzen

 

 

>  It seemed to me that 
the strake bottoms are too flat to concentrate
>contaminates. Try putting 
some water in an open strake and consider that the
>plane may often be 
tilted one way or another. Also consider the location of
>the drain holes 
in the valve body and where they will ultimately be in
>relation to the 
strake bottom. Each drain installation is a potential leak.
>  If a 
lot of water got into the system there may not be a good way to deal
>with 
it. The only thing I can think of would be a blister on the underside
>of 
each strake. The header is likely to be full when refuelling so it 
seems
>to me the water may reach it only after the plane has been flying 
for a
>while. Cheery thought.   -Bill
>
>prototype 
'Super' Chipmunk N18EF
>Velocity Classic RG N6098S in the 
works
>
>
>> I highly recommend sump drains.  One FBO 
pumped 3 gallons of water into my
>tanks,
>> and without sump 
drains I would have been in trouble.  When I checked 
for
>water
>> in the test cup it looked alright at first, then I 
noticed a small bead of
>fuel
>> floating on the top of the test 
sample.  So, it happens.  It is rare but
>it does
>> 
happen.
>>
>> LK
>
>