REFLECTOR: FUEL FEED [heur]

[Alex Balic]

Not that I condone that design change in any way, because I agree that it is
a bad idea- especially if the aircraft ends up on it's back from some
accident (fuel pouring into the hot engine compartment and all) but I could
see where some might think that it was a good idea to place the vent in a
high pressure area where it would not be exposed to ice or water ingestion.

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On
Behalf Of Scott Derrick
Sent: Wednesday, February 16, 2005 10:14 AM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: FUEL FEED [heur]



I think it is extremly dangerous to vent the fuel system into the engine
compartment!

Why would anybody do that???

Scott

Ron Brown wrote:

> Tom,
>
> I don't think it is a good idea to vent the fuel system into the
> engine compartment, especially if you happen to flip upside down
> during a crash landing.  You will have lots of fuel draining out the
> vent system into the hot engine compartment.
>
> With the factory designed fuel vent line routed up to the top of the
> firewall then back down to exit the bottom of the fuselage, fuel will
> not leak out of the vent system when the airplane is upside down.
>
> One other thought on uneven fuel flow, even if the vents are tied
> together and the plane is flying level/ball centered: there is a
> possibility that an air bubble trapped in the vent line with fuel on
> either side of the bubble can cause an uneven venting of the tanks.
> This wouldn't happen if the vent lines always slope upward to the
> manifold.  I think this may be the scenario that Jim Sower is seeing
> from time to time.  I have had it happen a couple of times on long
> trips after filling the tanks nearly full.  After landing and parking
> in my hanger, the fuel tanks were 5 or so gallons different and
> remained that way until I opened the fuel caps.  STRANGE!  Wings are
> level when parked in the hanger.  Another experiment - I placed a 2 x
> 6 under one main tire, simulating a wings down.  Guess what - the fuel
> level difference was MUCH LESS than I have seen in the air.
>
> But again, it could be fuel caps that are not always sealing perfectly
> for every flight.
>
> Ronnie
>
> ----- Original Message ----- From: "Tom Martino"
> <tmartino at troubleshooter.com>
> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> Sent: Tuesday, February 15, 2005 12:23 PM
> Subject: RE: REFLECTOR: FUEL FEED [heur]
>
>
> My plane flies perfectly.  Not my opinion, it is the assessment of my
> test pilot.  The ball is in the center and the plane flies "hands off"
> straight and level.
>
> I will keep looking.
>
> -----Original Message-----
> From: Scott Derrick [mailto:scott at tnstaafl.net]
> Sent: Tuesday, February 15, 2005 9:18 AM
> To: Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: FUEL FEED [heur]
>
> A leaking gas cap can cause uneven fuel flow but is not the prime
> culprit. A bit of fuel valve lube applied to the O ring once a year will
>
> insure this doesn't happen.
>
> A miss-rigged airplane is most likely the cause. Shim your rudders so
> the ball is right in the middle and you will get perfect fuel flow.
>
> To test, be sure your turn and bank is installed correctly first,
> garbage in garbage out. Then fly, this is the fun part.. Once you see an
>
> uneven condition, press on the rudder that will put the ball in the
> middle. If you want to even up the tanks fast, press on the correct
> rudder so the ball is on the other side for a couple minutes, you'll see
>
> the fuel even up and even go into the opposite imbalance if you keep the
>
> rudder depressed. Then hold the rudder so the ball is centered, fuel
> will flow as it was designed to.
>
> Scott
>
> Tom Martino wrote:
>
>> Well, now that I'm in my test flying mode ... I will really be asking
>> a lot of questions.
>>
>> Here are some of them, as they relate to my fuel system:
>>
>> 1. What makes the fuel tanks feed unevenly to the header tank/engine?
>> (My right tank is feeding twice as fast as my right tank.)
>>
>> 2. Will that cause a problem when the fast-feeding tank runs out?
>>
>> 3. I used the larger vent lines for my tanks and tied them al together
>
>
>> with a manifold, then vented the entire system out through the top of
>> my firewall in the engine compartment (about four inches below my naca
>
>
>> duct). Do you think the system gets enough venting there?
>>
>> 4. Is there a need for a "whistle" hole in any of the tank vents ...
>> for additional venting (like we do with the crankcase breather?
>>
>> Any help is appreciated from my more experienced Velocitologists J
>>
>> Tom
>>
>> N173EX
>>
>> (A mere 6 hours)
>>
>> -----------------------------------------------------------------------
>
> -
>
>>
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