REFLECTOR: Unbalanced fuel flow in flight

Richard J. Gentil richard at naples-air-center.com
Fri Mar 18 22:12:02 CDT 2011


For the fuel imbalance I ended up doing two things today. 

1) Worked on the plumbing to get the left tank on more of a down hill flow to the sump tank. One tube was slightly up hill. 

2) Took Laurence's advice and came up with an adjustable solution for the rudder stops. 

I took a piece of aluminium angle, drilled two slots in each and cut them flush with the rudder. It allowed me to easily adjust the rudder stop on either wing. 





I also used a piece of string taped at the base of the windshield to verify that the ball on the EFIS was accurate. 

With the ball in the center and the changes I made to the pluming, the fuel imbalance during today's flight was about 2 gallons which I am happy with and calling this issue done. 

Thank you all for your help!

Richard

Sent from my iPhone 4

On Mar 15, 2011, at 5:53 PM, "Laurence Coen" <lwcoen at hotmail.com> wrote:

> Rene,
>  
> Just the one stop.  I have detected no damage or denting of any kind to date.  When the rudder is against the stop, there is very little air load.  When the rudder slams against the stop the force is a function of the inertia of the rudder which is a light weight structure.  My rigging hasn't changed in 100 hours.
>  
> Larry Coen
> N136LC
> 
> From: Rene Dugas
> Sent: Monday, March 14, 2011 6:15 PM
> To: 'Velocity Aircraft Owners and Builders list'
> Subject: Re: REFLECTOR: Unbalanced fuel flow in flight
> 
> Good idea.  It seems to be a lot of pressure on a small area.  Do you have them at several points up the winglet?  If these are at the base as it appears (the spring) then is there another near the top of the rudder?  If not I would think as air load increases the upper rudder would warp and cause less effect which may be the desired effect.  Just asking.  I have two three inch platforms for the rudder to slam against.  One at the spring and one across from the top hinge.  Still may not be enough if I punch the rudder or if the wind slams the rudders over as occasionally happens.
> 
> Rene’
> 
>  
> 
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of Laurence Coen
> Sent: Monday, March 14, 2011 1:01 PM
> To: Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: Unbalanced fuel flow in flight
> 
>  
> 
> Richard,
> 
>  
> 
> I made my permanent fix before my first flight by installing adjustable rudder stops.  The attached fuzzy phone photos should give you an idea of how simple it was.  The screw mount and stop in the rudder root are 3/8" aluminum "U" channel.  The screw is a 8-32 stainless Allen head screwed into a nut plate.  Each turn = one mixing stick.  The "U" channel is pop riveted in place and sitting on a pad of stir stick/micro to transfer load to the rudder root and winglet root. IMHO it beats the heck out of gluing in shims and it took me less than an hour to make and install them.  I was all smiles when it came time to tweak my rudders.
> 
>  
> 
> Larry Coen
> 
> N136LC
> 
>  
> 
> From: Richard J. Gentil
> 
> Sent: Sunday, March 13, 2011 9:37 AM
> 
> To: Velocity Aircraft Owners and Builders list
> 
> Subject: Re: REFLECTOR: Unbalanced fuel flow in flight
> 
>  
> 
> I was circling over the field and I did change directions in the circle expecting the left tank to burn fuel while it was the high wing. It did not seem to happen. 
> 
>  
> 
> Fuel cap is air tight on both sides. Recently verified by pressurizing the system and leaving an airspeed indicator connected for several days. 
> 
>  
> 
> The ball is slightly out to the left. I hesitate to do a permanent fix till I get to the gear up and normal cruise test. 
> 
>  
> 
> 
> 
>  
> 
> I will conduct the string test next flight.  
> 
>  
> 
> Probably use some tongue depressors and five minute to set the yaw till I start flying with the gear up and set it permanently. 
> 
>  
> 
> Richard
> 
> 
> Sent from my iPhone 4
> 
> 
> On Mar 13, 2011, at 9:47 AM, John Abraham <jabraham03 at gmail.com> wrote:
> 
> Richard,
> 
> To add to Jerry and Scott, dont rely on your ball in the aircraft to be correct.  Tape a 6-12" string at the base of the wind screen (outside of aircraft) and you will be able to determine rigging better.  This will account for any panel installation errors.  I have experienced 10 gallons out of one tank before the other has moved.  Try to go for a flight long enough to burn off half a tank.  Be sure you change directions for circling too! That will affect feeding if you always make left turns, it will not let the left side feed as well.
> 
> John
> 
> On Sun, Mar 13, 2011 at 8:27 AM, Richard J. Gentil <richard at naples-air-center.com> wrote:
> 
> Friday I completed my second test flight.  I found that all the fuel drained from the right side and none from the left while on the one hour flight. (I actually cut the flight short due to this.)
> 
> When I landed I verified with my fuel stick that all the fuel did co e from the right tank.
> 
> For troubleshooting:
> 
> 1) I removed the line from the left tank to the sump tank and verified that fuel did flow freely from the left tank.
> 
> 2) Removed the vent line from the left tank and tested the line in the direction of the left tank and in the direction to the vent/overflow block at the top of my firewall using compressed air.
> 
> 3) I checked the check valve for the air for correct operation in both directions and verified it was installed in the correct direction for air to enter and that fuel would not vent into the cabin.
> 
> 4) Verified the overflow line was clear by using compressed air.
> 
> I know the picture is hard to follow but this is the fuel system:
> 
> 
> 
> 
> Richard
> 
> Sent from my iPhone 4
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> 
> 
> 
> -- 
> John Abraham
> CFII
> 321-543-6243
> 
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