REFLECTOR: Uneven Fuel Flow

Brooke Wolf bwolf1 at tds.net
Thu Sep 29 08:41:30 CDT 2011


>   

Ok, at the risk of showing my ignorance, I need to chime in here.

How could a minute leak in a fuel cap affect fuel flow out of a tank when that same tank has about a 3/8 inch hole in it vented to the outside (aka fuel vents)?

Brooke


> 
> 
> From: "John Abraham" <john at velocityaircraft.com>
> Date: September 29, 2011 8:06:09 AM EDT
> To: "'Velocity Aircraft Owners and Builders list'" <reflector at tvbf.org>
> Subject: Re: REFLECTOR: Reflector Digest, Vol 78, Issue 80 Uneven fuel flow
> Reply-To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
> 
> 
> Just an additional note to what Mark said.  If you have uneven fuel flow,
> you should also check the lip of the fuel ring on your tank.  When you fill
> up your tank or have an FBO do this for you if they hit the ring hard enough
> with the nozzle and either dent it or score it your cap will also not close
> properly.
> 
> 5-7 gallons different per side is acceptable.  The tanks are fighting each
> other by gravity pressure.  Also as a result of this if you are slightly out
> of rig; even half a ball, over the course of 2-3 hours on a trip you will
> have uneven feeding.  More than half a tank difference is unacceptable and
> you need to land to see what is going on with your system.  You do not want
> to wait until you are down to 3 gallons on one side while you have a full
> tank on the other side anticipating for it to feed.
> 
> You also want to make sure that your low fuel warning light works.  You can
> test it in flight without draining your tanks down.  Sometimes when you hit
> turbulence it will flash the light on and off a few times.  Also, if you
> stomp on the rudders back and forth 2-3 times it will make the switch
> trigger, flash the light and go out.
> 
> Safe flying,
> 
> John
> 
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
> Behalf Of Mark Riley
> Sent: Wednesday, September 28, 2011 8:56 PM
> To: reflector at tvbf.org
> Subject: Re: REFLECTOR: Reflector Digest, Vol 78, Issue 80 Uneven fuel flow
> 
> On my XL I had uneven fuel flow and asked Duane Swing to take a look when we
> stopped in Sebastian on the way to the Bahamas. He noticed two problems I
> never would have caught. The O rings on the filler cap had minute flecks of
> primer paint on them, which prevented them from creating an airtight seal.
> Andy Millin and I spent an hour picking it off with our fingernails then
> greasing them up with fuel lube. He also noticed that the gap around the
> filler caps was too tight, so that it prevented the cap on one side from
> seating properly. We just sanded it back ever so slightly until the cap
> didn't rock at all when latched shut. If you try these fixes and still
> wonder about your caps, you can try covering them with duct tape. Even a
> minute problem like I've described can cause uneven drainage from the tanks
> even in a properly rigged plane. 
> 
> Two more thoughts - first, it is not uncommon for the tanks to drain
> unevenly but catch up to each other. One of my tanks always drains faster
> between about 25 and 17 gallons, then the other one catches up. Second, if
> the tanks get uneven, you can simply slip the plane for 1-2 minutes with the
> uneven tank up. I find that they then drain evenly. I tried this for the
> first time 100 miles from the nearest land on my way back to pick up the
> Millins. Probably better to try it in a more comfortable setting first. 
> 
> Hope that helps.
> 
> Mark
> On Sep 28, 2011, at 8:32 PM, reflector-request at tvbf.org wrote:
> 
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>> Today's Topics:
>> 
>>  1. Re:  STD RG Trim (Scott Derrick)
>>  2. Re:  STD RG Trim (Glenn Babcock)
>> 
>> 
>> ----------------------------------------------------------------------
>> 
>> Message: 1
>> Date: Wed, 28 Sep 2011 17:05:12 -0700
>> From: Scott Derrick <scott at tnstaafl.net>
>> Subject: Re: REFLECTOR: STD RG Trim
>> To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
>> Message-ID: <050fue2q67u5ay5mcgjyf6a6.1317254691797 at email.android.com>
>> Content-Type: text/plain; charset="utf-8"
>> 
>> The unequal fuel born is because of the miss adjusted rudder trim.  The
> fuel is acting as a really big BALL and is moving with the litttle ball.
>> 
>> Glenn Babcock <glennbabcock at roadrunner.com> wrote:
>> 
>>> Izzy,
>>> 
>>> Here's what I did:
>>> 
>>> - On the ground, level the plane.  Use a rotary laser level to level the
> wings left to right, you can get one for under $100.  Put sawhorses or
> something under the wings to hold the position.  Also level the plane front
> to back.
>>> - Verify that the wing incidence is correct for both wings using the
> incidence gauge.  While you're at it verify the canard incidence.
>>> - Verify the strake leading edge position on both sides.
>>> - If needed, shim the wings and/or canard.  If the strakes are out that's
> a more complicated fix!
>>> - Now check that the TC is level (mine wasn't, making the problem look
> worse than it was).  The ball should be right in the center.
>>> - If you made no corrections in the wings or canard, shim the rudder (if
> you made corrections, test fly first to see if it's still out).  I found
> that you can hot glue bits of tongue depressor at the top, middle and bottom
> of the rudder then trim them down as needed.  A small amount of shim makes a
> big difference!  Make sure that the rudder touches all three shims when it's
> resting.
>>> - Also check the opposite rudder, you may be able to trim a SMALL amount
> off of that side.
>>> - Once you have the correct amount of shim, fill the gap with epoxy mixed
> with micro glass or flox, then after it cures sand it till it's neat.  It's
> very easy to do.
>>> 
>>> The fuel not draining evenly may be due to a leaking fuel cap.  Remove
> the cap and coat the O-rings with Fuelube.  Make sure you get the little one
> on the stem as well as the big one on the rim.
>>> 
>>> Regards,
>>> Glenn
>>> 
>>> 
>>> On Sep 28, 2011, at 9:06 AM, Dugas Bellsouth wrote:
>>> 
>>>> I did the same only used 1/16" angle aluminum. I trimmed a 1.5" so when
> placed inside of the winglet it was flush with the airflow surface on the
> fuselage side of the winglet. I the epoxied it to the inside of the winglet
> and flew. Worked great. Still there and did not require all the glass work. 
>>>> 
>>>> Rene' Dugas
>>>> Sent from my iPhone4
>>>> 
>>>> On Sep 27, 2011, at 5:56 PM, Scott Derrick <scott at tnstaafl.net> wrote:
>>>> 
>>>>> Trim the left rudder out until the ball is in the center.
>>>>> 
>>>>> Tape the vertical with duct tape near the lower part of the rudder.
> Place a shim between the rudder and the vertical, about an 1/8 inch thick.
> Then fill the gap with micro or epoxy glue, about 2 inches long, so it
> sticks to the rudder.  Let cure, clean it up and fly. If that was to much
> file the new tab down a bit and test fly again.  If the ball is still out,
> add another 1/8 inch and test fly.  Do this until the ball is in the center.
> 
>>>>> 
>>>>> Once you have the ball in the center, yaw trim, you can evaluate the
> roll trim.   If the plane still wants to roll and the roll trim cannot
> handle that you can shim both or one wing.  You usually want to shim the
> light wing first by taking some of the aoa out of that wing by shimming the
> lower bolt. If thta s not enough add in more aoa to the heavy wing by
> shimming the upper bolts.
>>>>> 
>>>>> Scott
>>>>> 
>>>>> Izzy Brownfield <iznstacy at yahoo.com> wrote:
>>>>> 
>>>>>> I'm a new owner of a STD RG with io-360 three blade MT prop At 
>>>>>> cruise T&B indicator is half ball to the left with a slight left turn
> tendency. Fuel is consumed from the right tank at twice the rate of the left
> tank.
>>>>>> To center the ball it requires quite a bit of left rudder and light
> right aileron pressure. 
>>>>>> What adjustment is needed to be made to correct this?
>>>>>> Thanks
>>>>>> Izzy
>>>>>> 5txo
>>>>>> 
>>>>>> Sent from my iPhone
>>>>>> _______________________________________________
>>>>>> To change your email address, visit 
>>>>>> http://www.tvbf.org/mailman/listinfo/reflector
>>>>>> 
>>>>>> Visit the gallery!  www.tvbf.org/gallery user:pw = 
>>>>>> tvbf:jamaicangoose Check new archives: www.tvbf.org/pipermail 
>>>>>> Check old archives: 
>>>>>> http://www.tvbf.org/archives/velocity/maillist.html
>>>>> _______________________________________________
>>>>> To change your email address, visit 
>>>>> http://www.tvbf.org/mailman/listinfo/reflector
>>>>> 
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>> ------------------------------
>> 
>> Message: 2
>> Date: Wed, 28 Sep 2011 19:32:42 -0500
>> From: Glenn Babcock <glennbabcock at roadrunner.com>
>> Subject: Re: REFLECTOR: STD RG Trim
>> To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
>> Message-ID: <F71FDCA0-9D0C-4A13-88A1-B6991DFA73A4 at roadrunner.com>
>> Content-Type: text/plain; charset="us-ascii"
>> 
>> It may be that or it may not, or it may be both.  I know that many people
> have chased fuel flow problems all around the aircraft only to find the fuel
> caps were leaking, causing a drop in pressure in one tank and restricting
> fuel flow on that side.  A tiny amount of Fuelube and about 5 minutes effort
> and the problem is solved.
>> 
>> Regards,
>> Glenn
>> 
>> 
>> On Sep 28, 2011, at 7:05 PM, Scott Derrick wrote:
>> 
>>> The unequal fuel born is because of the miss adjusted rudder trim. The
> fuel is acting as a really big BALL and is moving with the litttle ball.
>>> 
>>> Glenn Babcock <glennbabcock at roadrunner.com> wrote:
>>> 
>>> Izzy,
>>> 
>>> Here's what I did:
>>> 
>>> - On the ground, level the plane.  Use a rotary laser level to level the
> wings left to right, you can get one for under $100.  Put sawhorses or
> something under the wings to hold the position.  Also level the plane front
> to back.
>>> - Verify that the wing incidence is correct for both wings using the
> incidence gauge.  While you're at it verify the canard incidence.
>>> - Verify the strake leading edge position on both sides.
>>> - If needed, shim the wings and/or canard.  If the strakes are out that's
> a more complicated fix!
>>> - Now check that the TC is level (mine wasn't, making the problem look
> worse than it was).  The ball should be right in the center.
>>> - If you made no corrections in the wings or canard, shim the rudder (if
> you made corrections, test fly first to see if it's still out).  I found
> that you can hot glue bits of tongue depressor at the top, middle and bottom
> of the rudder then trim them down as needed.  A small amount of shim makes a
> big difference!  Make sure that the rudder touches all three shims when it's
> resting.
>>> - Also check the opposite rudder, you may be able to trim a SMALL amount
> off of that side.
>>> - Once you have the correct amount of shim, fill the gap with epoxy mixed
> with micro glass or flox, then after it cures sand it till it's neat.  It's
> very easy to do.
>>> 
>>> The fuel not draining evenly may be due to a leaking fuel cap.  Remove
> the cap and coat the O-rings with Fuelube.  Make sure you get the little one
> on the stem as well as the big one on the rim.
>>> 
>>> Regards,
>>> Glenn
>>> 
>>> 
>>> On Sep 28, 2011, at 9:06 AM, Dugas Bellsouth wrote:
>>> 
>>>> I did the same only used 1/16" angle aluminum. I trimmed a 1.5" so when
> placed inside of the winglet it was flush with the airflow surface on the
> fuselage side of the winglet. I the epoxied it to the inside of the winglet
> and flew. Worked great. Still there and did not require all the glass work. 
>>>> 
>>>> Rene' Dugas
>>>> Sent from my iPhone4
>>>> 
>>>> On Sep 27, 2011, at 5:56 PM, Scott Derrick <scott at tnstaafl.net> wrote:
>>>> 
>>>>> Trim the left rudder out until the ball is in the center.
>>>>> 
>>>>> Tape the vertical with duct tape near the lower part of the rudder.
> Place a shim between the rudder and the vertical, about an 1/8 inch thick.
> Then fill the gap with micro or epoxy glue, about 2 inches long, so it
> sticks to the rudder.  Let cure, clean it up and fly. If that was to much
> file the new tab down a bit and test fly again.  If the ball is still out,
> add another 1/8 inch and test fly.  Do this until the ball is in the center.
> 
>>>>> 
>>>>> Once you have the ball in the center, yaw trim, you can evaluate the
> roll trim.   If the plane still wants to roll and the roll trim cannot
> handle that you can shim both or one wing.  You usually want to shim the
> light wing first by taking some of the aoa out of that wing by shimming the
> lower bolt. If thta s not enough add in more aoa to the heavy wing by
> shimming the upper bolts.
>>>>> 
>>>>> Scott
>>>>> 
>>>>> Izzy Brownfield <iznstacy at yahoo.com> wrote:
>>>>> 
>>>>>> I'm a new owner of a STD RG with io-360 three blade MT prop At 
>>>>>> cruise T&B indicator is half ball to the left with a slight left turn
> tendency. Fuel is consumed from the right tank at twice the rate of the left
> tank.
>>>>>> To center the ball it requires quite a bit of left rudder and light
> right aileron pressure. 
>>>>>> What adjustment is needed to be made to correct this?
>>>>>> Thanks
>>>>>> Izzy
>>>>>> 5txo
>>>>>> 
>>>>>> Sent from my iPhone
>>>>>> _______________________________________________
>>>>>> To change your email address, visit 
>>>>>> http://www.tvbf.org/mailman/listinfo/reflector
>>>>>> 
>>>>>> Visit the gallery!  www.tvbf.org/gallery user:pw = 
>>>>>> tvbf:jamaicangoose Check new archives: www.tvbf.org/pipermail 
>>>>>> Check old archives: 
>>>>>> http://www.tvbf.org/archives/velocity/maillist.html
>>>>> _______________________________________________
>>>>> To change your email address, visit 
>>>>> http://www.tvbf.org/mailman/listinfo/reflector
>>>>> 
>>>>> Visit the gallery!  www.tvbf.org/gallery user:pw = 
>>>>> tvbf:jamaicangoose Check new archives: www.tvbf.org/pipermail Check 
>>>>> old archives: http://www.tvbf.org/archives/velocity/maillist.html
>>>> _______________________________________________
>>>> To change your email address, visit 
>>>> http://www.tvbf.org/mailman/listinfo/reflector
>>>> 
>>>> Visit the gallery!  www.tvbf.org/gallery user:pw = 
>>>> tvbf:jamaicangoose Check new archives: www.tvbf.org/pipermail Check 
>>>> old archives: http://www.tvbf.org/archives/velocity/maillist.html
>>> 
>>> _______________________________________________
>>> To change your email address, visit 
>>> http://www.tvbf.org/mailman/listinfo/reflector
>>> 
>>> Visit the gallery!  www.tvbf.org/gallery user:pw = tvbf:jamaicangoose 
>>> Check new archives: www.tvbf.org/pipermail Check old archives: 
>>> http://www.tvbf.org/archives/velocity/maillist.html
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