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observations on fuel imbalance discussion

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brian(at)lloyd.com
Guest

Posted: Fri Feb 17, 2012 2:43 pm Post subject: observations on fuel imbalance discussion

Ah, how we love to take sides. 



So, while you are busy deciding who is right and who is wrong, please consider:

Whether or not we like the person making the posting has no effect on the reality of the situation.  
Given the number of variables and unless you have a very-well-controlled environment in which you are collecting data, in-flight anecdotal "evidence" is always suspect. 
That being said, there are quite a few CJ6A and Yak-52 aircraft that respond well to slipping the aircraft slightly in order to favor fuel flow from one tank or the other to even out flow, thus implying that there is no endemic problem with either the fuel system or vent system design. (My own experience is that 100% of the CJ6A and Yak-52 aircraft that I have flown have responded to this means of evening fuel flow from the tanks but I refer you to item #2 above.) 
Only a rigidly-controlled test is going to determine if a particular aircraft has an asymmetric fuel-flow problem.So, if you think you have a problem I recommend the following:

Inspect your fuel and vent system, replacing old rubber hose and cleaning all hard lines. (I suspect some people might have a problem with partially pinched rubber flex lines. I know of one aircraft that had a small flap of rubber that was partially obstructing a fuel line from an improperly-installed fitting.) 
Jack up your plane and meticulously level it.
Disconnect the fuel line from the header tank at the fuel pump inlet and let it drain into a large catch drum at a 1L/min rate (equivalent to normal cruise fuel consumption). 
Periodically tap/bang on the header tank to ensure that the flapper valves do not stick closed.
After some period of time determine the actual fuel imbalance.This will give you good data about your particular aircraft independent of your own flying habits/characteristics.

 

And I wish everyone on the list a pleasant weekend of flying.

-- 

Brian Lloyd, WB6RQN/J79BPL

3191 Western Dr.

Cameron Park, CA 95682

brian(at)lloyd.com (brian(at)lloyd.com)

 +1.767.617.1365 (Dominica)

+1.916.877.5067 (USA)



 



  [quote][b]

mark.bitterlich(at)navy.m
Guest

Posted: Sun Feb 19, 2012 12:30 pm Post subject: observations on fuel imbalance discussion

I own a UTVA-66 as well as a YAK-50.  Obviously the "slipping method"

does not work on the 50. 



However, on the UTVA-66, I can make the fuel gages in either wing read

whatever I want by slipping the aircraft.  I can go from empty to half

full on either tank simply by stepping on the rudder.  Since there is no

easy way for huge amounts of fuel to change tanks in 5 seconds, it is

likely that I am only impacting the readings of the fuel gage.  



That said, I have learned a very simple way to determine fuel flow, and

the amount left in the tank. 



When it becomes very very quiet, the selected tank has no more fuel in

it.  



Works for me.



Mark Bitterlich



p.s.  Yes, I know CJ's and 52's don't have selectable tanks.  Sigh .....



 



--

viperdoc(at)mindspring.co
Guest

Posted: Sun Feb 19, 2012 4:29 pm Post subject: observations on fuel imbalance discussion

Mark,

ROFLMAO

Doc



Sent from my iPad



On Feb 19, 2012, at 2:28 PM, "Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E" <mark.bitterlich(at)navy.mil> wrote:



[quote] 

 

 I own a UTVA-66 as well as a YAK-50.  Obviously the "slipping method"

 does not work on the 50. 

 

 However, on the UTVA-66, I can make the fuel gages in either wing read

 whatever I want by slipping the aircraft.  I can go from empty to half

 full on either tank simply by stepping on the rudder.  Since there is no

 easy way for huge amounts of fuel to change tanks in 5 seconds, it is

 likely that I am only impacting the readings of the fuel gage.  

 

 That said, I have learned a very simple way to determine fuel flow, and

 the amount left in the tank. 

 

 When it becomes very very quiet, the selected tank has no more fuel in

 it.  

 

 Works for me.

 

 Mark Bitterlich

 

 p.s.  Yes, I know CJ's and 52's don't have selectable tanks.  Sigh .....

 

 

 

 

 

 --

mark.bitterlich(at)navy.m
Guest

Posted: Tue Feb 21, 2012 9:44 am Post subject: observations on fuel imbalance discussion

Glad you laughed!  



Mark

--

Pete Fowler

Joined: 07 Jul 2009
Posts: 76
Location: California

Posted: Sun Mar 11, 2012 7:28 am Post subject: Re: observations on fuel imbalance discussion

And remember, on the CJ, the fact the fuel sump is 1 foot closer to the left tank than the right and it's WELL to the left of the centerline of the aircraft doesn't have anything whatever to do with it

brian(at)lloyd.com
Guest

Posted: Sun Mar 11, 2012 8:22 am Post subject: observations on fuel imbalance discussion

On Sun, Mar 11, 2012 at 8:28 AM, Pete Fowler <pfdesign1(at)cox.net (pfdesign1(at)cox.net)> wrote:

 	  Quote: 	
		   --> Yak-List message posted by: "Pete Fowler" <pfdesign1(at)cox.net (pfdesign1(at)cox.net)>

 

 And remember, on the CJ, the fact the fuel sump is 1 foot closer to the left tank than the right and it's WELL to the left of the centerline of the aircraft doesn't have anything whatever to do with it  [Rolling Eyes]

 	




Not  if the aircraft is flying coordinated. In that case the "head" is the same for both tanks regardless of where the header tank is positioned laterally (left or right of the center-line). That also determines static fuel pressure. Given the same resistance to flow from both wings to the header tank, the means that, for the same head, you will have the same flow. 

 



But even a small change in the coordination of the aircraft will then have an effect on the flow from the tanks because the head for each fuel tank will be different. This is why it is so important to make sure that you level your airplane and then precisely adjust the balls to be in the center. 

 



FWIW, 100% of the airplanes I have checked have had their balls not centered when the aircraft was leveled. (In most, the instruments didn't even agree with each other, let alone indicate level.) And it is so easy to do that I don't understand why people don't do it. When the aircraft is on jacks for a gear-swing, lay a bubble level across the canopy rails. Adjust the jacks until the aircraft is level according to the bubble level. climb into the cockpits, loosen the screws on the AI and needle/ball, and rotate them until the balls are in the center. Retighten the screws. Done.

 



Now you can believe your balls when they tell you that you are not coordinated. 



-- 

Brian Lloyd, WB6RQN/J79BPL

3191 Western Dr.

Cameron Park, CA 95682

brian(at)lloyd.com (brian(at)lloyd.com)

 +1.767.617.1365 (Dominica)

+1.916.877.5067 (USA)



  [quote][b]

jcolquit(at)law.ua.edu
Guest

Posted: Mon Mar 12, 2012 6:46 am Post subject: observations on fuel imbalance discussion

Mr. Lloyd observes:  

   

<![if !supportLists]>Ø  <![endif]>“Now you can believe your balls when they tell you that you are not coordinated.”  

   

I’ll let the statement speak for itself.   

   

I am curious though; was it was intended as a double entendre? Or as a test to see if one was really reading the message?  

   

Joe Colquitt  

CJ-6A – coordinated all the way – I hope  

      [quote][b]

cjpilot710(at)aol.com
Guest

Posted: Mon Mar 12, 2012 7:05 am Post subject: observations on fuel imbalance discussion

Do you realize that one's balls change with ambient temperature?

    

   Jim "Pappy" Goolsby

 

 

 

   --

brian(at)lloyd.com
Guest

Posted: Mon Mar 12, 2012 8:08 am Post subject: observations on fuel imbalance discussion

On Mon, Mar 12, 2012 at 7:42 AM, Joseph Colquitt <jcolquit(at)law.ua.edu (jcolquit(at)law.ua.edu)> wrote:

 	  Quote: 	
		                

Mr. Lloyd observes:  

   

Ø  “Now you can believe your balls when they tell you that you are not coordinated.”  

   

I’ll let the statement speak for itself.   

   

I am curious though; was it was intended as a double entendre? Or as a test to see if one was really reading the message?



	




After 57 years I have come to really appreciate the English language. It is so flexible. The double entendre is often a useful tool when trying to cement an idea in the mind of someone who is hard-headed. 

 



Or just good for a laugh.

But sometimes, they just happen. 

Next week -- Spoonerisms.



-- 

Brian Lloyd, WB6RQN/J79BPL

3191 Western Dr.

 Cameron Park, CA 95682

brian(at)lloyd.com (brian(at)lloyd.com)

+1.767.617.1365 (Dominica)

+1.916.877.5067 (USA)



  [quote][b]

brian(at)lloyd.com
Guest

Posted: Mon Mar 12, 2012 8:09 am Post subject: observations on fuel imbalance discussion

On Mon, Mar 12, 2012 at 8:00 AM, " <cjpilot710(at)aol.com (cjpilot710(at)aol.com)> wrote:

 	  Quote: 	
		    Do you realize that one's balls change with ambient temperature?

	




Only if one uses the wrong damping fluid.



-- 

Brian Lloyd, WB6RQN/J79BPL

 3191 Western Dr.

Cameron Park, CA 95682

brian(at)lloyd.com (brian(at)lloyd.com)

+1.767.617.1365 (Dominica)

+1.916.877.5067 (USA)



  [quote][b]

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