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Yak 52TW Fuel Starvation at near zero G
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ggtyler

Joined: 05 Mar 2016
Posts: 29

Posted: Wed Dec 12, 2018 9:59 am Post subject: Yak 52TW Fuel Starvation at near zero G

Just looking for some second opinions and if anyone else has experienced this. 



Last week I spent 3 days doing spin and aerobatic training with Sergei Boriak in my Yak 52TW. Everything went great until the last flight of our third day. Doing a loop, just up near the top where you start to float over, the engine coughed and one or two seconds later coughed again.



We were at 2100 RPM and 29 Inches. Up near the top of the loop we were just getting into a misty cloud layer. Carb heat was not on. 



It most definitely felt like fuel starvation. I'm familiar with mag issues, and the airplane has all new mags and wires 10 hours ago. Was a definite cough, not a misfire. 



Similar experiences? Any ideas? Solutions?

cerveirapinto(at)gmail.co
Guest

Posted: Wed Dec 12, 2018 10:23 am Post subject: Yak 52TW Fuel Starvation at near zero G

What was the fuel quantity in each tank?If it was less than 20 in any tank that was the problem.

Cheers.

Na(o) quarta, 12/12/2018, 18:08, ggtyler <ggtyler(at)gmail.com (ggtyler(at)gmail.com)> escreveu:



 	  Quote: 	
		  --> Yak-List message posted by: "ggtyler" <ggtyler(at)gmail.com (ggtyler(at)gmail.com)>

 

 Just looking for some second opinions and if anyone else has experienced this. 

 

 Last week I spent 3 days doing spin and aerobatic training with Sergei Boriak in my Yak 52TW. Everything went great until the last flight of our third day. Doing a loop, just up near the top where you start to float over, the engine coughed and one or two seconds later coughed again.

 

 We were at 2100 RPM and 29 Inches. Up near the top of the loop we were just getting into a misty cloud layer. Carb heat was not on. 

 

 It most definitely felt like fuel starvation. I'm familiar with mag issues, and the airplane has all new mags and wires 10 hours ago. Was a definite cough, not a misfire. 

 

 Similar experiences? Any ideas? Solutions?

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=486255#486255

 

 

 

 

 

 

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ggtyler

Joined: 05 Mar 2016
Posts: 29

Posted: Wed Dec 12, 2018 4:46 pm Post subject: Re: Yak 52TW Fuel Starvation at near zero G

My aircraft has 21 gallon primary tanks in each wing, and I had at least 13 gallons in each tank.

wlannon(at)shaw.ca
Guest

Posted: Wed Dec 12, 2018 8:45 pm Post subject: Yak 52TW Fuel Starvation at near zero G

Yes but (for a second or two) that 13 gals. was sitting on the top side of 

the tank while the outlet on the bottom was sucking air.



Should not have been a problem since the fuel feed system (header tank or 

whatever) should have handled that seamlessly.

You need to study and understand your fuel system.



Walt



--

ggtyler

Joined: 05 Mar 2016
Posts: 29

Posted: Wed Dec 12, 2018 11:41 pm Post subject: Re: Yak 52TW Fuel Starvation at near zero G

Walt, I'm pretty sure I have a decent handle on the fuel system. I've got a header tank under the feet, with a flop tube, and then the fuel globe on the front side of the firewall and a pressure carb. I was under the impression that this system was specifically designed to supply fuel for even a couple minutes of sustained inverted flight.



Are you suggesting that fuel starvation during aerobatics could be considered normal in a Yak 52? Sergei didn't seem to think so. He's got thousands of hours in the Yak 52 and the first words out of his mouth were "that's not good". 



I'm trying to assess if this has been an occasional rare occurrence for other Yak owners, and what the possible solutions might be.

dsavarese0812(at)bellsout
Guest

Posted: Thu Dec 13, 2018 5:31 am Post subject: Yak 52TW Fuel Starvation at near zero G

Walt has definitely pointed you in the right direction.  When inverted, the Yak 52 including the TW, has a flop tube inside the header tank that "flips" over when the aircraft is inverted.  Fuel is never fed directly from the fuel tanks in the 52's.  It's always fed from the header tank.  Actually, "fed" is not a proper term.  It is consumed from the header tank.  The fuel tanks refill the header tank.

Do you know why the Yak 52's are limited to 2 minutes inverted flight?  It's because of the capacity of the header tank.

Since it's a TW, the flop tube in the header tank is not as old as the original 52's.  But it is a flexible hose inside the header tank.  If the flop tube is or has becoming brittle, maybe the flop tube is not functioning as it should.  So don't discount this as a potential cause of what you experienced  Quite honestly, the flop tube is THE most neglected flexible line in a Yak 52. I'm sure you can see why.



I'm attaching a cut-a-way drawing of the 52's header tank.  Look at the lower right side of this original Russian training placard where you can see the flop tube.  (Yes, the placard is of an original Yak 52.  But the header tank is the same.)



[img]cid:22f45f35-4abe-579d-ff72-a319f91be345(at)yahoo.com[/img]

Dennis





       From: Walter Lannon <wlannon(at)shaw.ca>

 To: yak-list(at)matronics.com 

 Sent: Wednesday, December 12, 2018 11:48 PM

 Subject: Re: Re: Yak 52TW Fuel Starvation at near zero G

  

 

--> Yak-List message posted by: "Walter Lannon" <wlannon(at)shaw.ca (wlannon(at)shaw.ca)>



Yes but (for a second or two) that 13 gals. was sitting on the top side of 



the tank while the outlet on the bottom was sucking air.



Should not have been a problem since the fuel feed system (header tank or 



whatever) should have handled that seamlessly.



You need to study and understand your fuel system.



Walt



--

Fuel_System.jpg

Description:

Filesize:

343.58 KB

Viewed:

10600 Time(s)

dsavarese0812(at)bellsout
Guest

Posted: Thu Dec 13, 2018 6:01 am Post subject: Yak 52TW Fuel Starvation at near zero G

No, fuel starvation is not normal and I'm certain Walt is not even remotely suggesting that.   The fuel "globe" as you called it is a debubbler.  It functions like an accumulator tank for water systems as used on boats with cabin and head accommodations.  The water pump pulses water outward.  With an accumulator tank, the pulses are removed and when the water faucet is turned on, the water flows out smoothly, without pulses.   Everything AFTER the fuel pump, which includes the "globe" and the fine fuel screen and the carburetor are slaved to whatever the fuel pump is able to pump forward toward the carburetor.  If it were my airplane, I would start looking at the header tank and the flop tube.  That's where the fuel comes from to feed the beast.

Dennis

       From: ggtyler <ggtyler(at)gmail.com>

 To: yak-list(at)matronics.com 

 Sent: Thursday, December 13, 2018 2:45 AM

 Subject: Re: Yak 52TW Fuel Starvation at near zero G

--> Yak-List message posted by: "ggtyler" <ggtyler(at)gmail.com (ggtyler(at)gmail.com)>

Walt, I'm pretty sure I have a decent handle on the fuel system. I've got a header tank under the feet, with a flop tube, and then the fuel globe on the front side of the firewall and a pressure carb. I was under the impression that this system was specifically designed to supply fuel for even a couple minutes of sustained inverted flight.

Are you suggesting that fuel starvation during aerobatics could be considered normal in a Yak 52? Sergei didn't seem to think so. He's got thousands of hours in the Yak 52 and the first words out of his mouth were "that's not good". 

I'm trying to assess if this has been an occasional rare occurrence for other Yak owners, and what the possible solutions might be.

Read this topic online here:

http://forums.matronics.com/viewtopic.php?p=486270#486270

http://www.matronics.com/contribbsp;                 -Matt Dralle, bsp;     - The Yak-List Email Forum -

_-= Use the Matronics List Features Navigator to browse

ht=====================

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wlannon(at)shaw.ca
Guest

Posted: Thu Dec 13, 2018 10:19 am Post subject: Yak 52TW Fuel Starvation at near zero G

No I am not suggesting anything of the sort.   If you would re-read my 

second paragraph you will understand that.



My post was a response to your's  implying the amount if fuel in the main 

tanks was enough to to ensure this hesitation should not have happened.

My response was to simply advise you that the amount of fuel in the mains 

was immaterial and the problem lies somewhere in the fuel management system.



Cheers;

Walt



--

markdavis(at)wbsnet.org
Guest

Posted: Thu Dec 13, 2018 10:59 am Post subject: Yak 52TW Fuel Starvation at near zero G

What everyone is possibly not considering is that the flop tube is held in

good fuel by either positive g or negative g.  O g where the issue arose

could have the flop tube out of the fuel if sustained for a long enough time

of the hose is becoming somewhat stiff.



Mark Davis

N44K

--

saber369(at)comcast.net
Guest

Posted: Thu Dec 13, 2018 12:32 pm Post subject: Yak 52TW Fuel Starvation at near zero G

While we are on the subject of fuel flow, header tanks, etc.  I have a question about the CJ fuel system.



Not long after I bought my CJ I was returning home from a full day of formation flying.  My CJ, not unlike many others, has an asymmetrical fuel feed issue meaning it drains from one tank more than the other based on trim or rather imbalanced trim.  On this day, as I neared home, the right tank had about 30 liters indicated and the left tank was approaching zero.   Just as I arrived at the initial entry point over the runway with the left fuel low light on steady for a few minutes, the engine quit.  While this sudden silence quickly got my attention, I wasn't all that worried because I was over the runway.  I entered a left bank planning to continue with a circling approach and land with the engine out, but then after about 3-5 seconds in the left bank the engine caught up and continued operating normally.  I landed immediately without any further issues. 



Being an FNG to the CJ back then, I started calling some of the old timers asking their opinions.  All agreed that it was most likely a fuel issue, or lack of fuel on one side and as long as I had gas in both tanks I shouldn't experience any additional problems.  So, with ample gas in both tanks, I did several minutes of ground test runs at varying RPMs; high-speed taxi checks and after an hour or so took off and completed a successful test flight.  



So the simple question is... Why did this happen?  I repeated the scenario a few years later; this time on purpose and over the long runway with the same results.  I replicated the same conditions with one exception... when the engine "quit" I delayed entering a turn for a few seconds (seemed like hours with all that quite in front of me) to see what would happen.  After a short delay, I entered the left bank and sure enough, the engine regained full RPM with no additional issues.  



Why did this happen?  The main tanks feed the header tank, so in theory, the fuel tank with gas should continue to feed the header regardless - right?  I would think that the header tank, being center-line to the engine, would continue to drain fuel from the tank with gas and feed fuel to the engine regardless of any delta in fuel tank quantities.  



After I repeated the incident on purpose, I once again called around for opinions and the one thing that I will remember and have passed on to FNGs is something Doug Sapp said... "There are a lot of CJs laying on their bellies in corn fields with 60 liters in one side and zero in the other."



I know many will give opinions on the asymmetrical fuel flow, but that's not the question... the header tank is the question.  And for those who want to tell me about setting proper trim, I've got the trim tabs well balanced, but still have to "step on the fuller tank" to get it back to "30-30" in both tanks.  Help me understand the header tank thing and we can talk about trim later please.



Jon Blake

Saber369(at)comcast.net

[quote] On December 13, 2018 at 12:59 PM Mark Davis <markdavis(at)wbsnet.org> wrote:

 

 

 

 

 What everyone is possibly not considering is that the flop tube is held in

 good fuel by either positive g or negative g.  O g where the issue arose

 could have the flop tube out of the fuel if sustained for a long enough time

 of the hose is becoming somewhat stiff.

 

 Mark Davis

 N44K

 

 

 --

bwade154(at)yahoo.com
Guest

Posted: Thu Dec 13, 2018 1:29 pm Post subject: Yak 52TW Fuel Starvation at near zero G

OK and MOST important what was Sergei's thought's on what happened? Everyone seems to indicate that there is a flop tube in the header tank I'm not so sure I think the fuel flows in on the top and exits on the top and the only way to use the two gal in the header tank is to fly inverted or use the primer, I think that the primer pulls fuel from the bottom of the header tank (upright flight) my reasoning is that I've read stories from pilots running out of fuel and keeping the engine running long enough to make an airport by pumping the primer, therefor there was fuel available to the primer but not the system. Just before the header tank there are valves in the fuel lines that DO NOT allow fuel to flow from wing to wing or header tank to wing tanks. The Header tank is also vented so when inverted that is the engines only source of fuel thus the two minute limitation. And that's my two cents, worth every penny.

                  

                                                                    On â€ŽWednesdayâ€Ž, â€ŽDecemberâ€Ž â€Ž12â€Ž, â€Ž2018â€Ž â€Ž01â€Ž:â€Ž17â€Ž:â€Ž13â€Ž â€ŽPMâ€Ž â€ŽEST, ggtyler <ggtyler(at)gmail.com> wrote:                 

                 



                 



                 --> Yak-List message posted by: "ggtyler" <ggtyler(at)gmail.com (ggtyler(at)gmail.com)>



Just looking for some second opinions and if anyone else has experienced this. 



Last week I spent 3 days doing spin and aerobatic training with Sergei Boriak in my Yak 52TW. Everything went great until the last flight of our third day. Doing a loop, just up near the top where you start to float over, the engine coughed and one or two seconds later coughed again.



We were at 2100 RPM and 29 Inches. Up near the top of the loop we were just getting into a misty cloud layer. Carb heat was not on. 



It most definitely felt like fuel starvation. I'm familiar with mag issues, and the airplane has all new mags and wires 10 hours ago. Was a definite cough, not a misfire. 



Similar experiences? Any ideas? Solutions?



Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=486255#486255







sp;      (And Get Some AWESOME FREE Gifts!)



http://www.matronics.com/contributp;                 -Matt Dralle, Libsp;     - The Yak-List Email Forum -



_-= Use the Matronics List Features Navigator to browse



http://www.matronics.com/Navigator?Yak-List



http://forums.matronics.c;         - NEW MATRONICS LIST WIKI -



http://wiki.matronics.com



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bwade154(at)yahoo.com
Guest

Posted: Thu Dec 13, 2018 1:43 pm Post subject: Yak 52TW Fuel Starvation at near zero G

Many years ago I did have a similar stumble happen to me in a loop and found water in the firewall sump and the glob.

                  

                                                                    On â€ŽWednesdayâ€Ž, â€ŽDecemberâ€Ž â€Ž12â€Ž, â€Ž2018â€Ž â€Ž01â€Ž:â€Ž17â€Ž:â€Ž13â€Ž â€ŽPMâ€Ž â€ŽEST, ggtyler <ggtyler(at)gmail.com> wrote:                 

                 



                 



                 --> Yak-List message posted by: "ggtyler" <ggtyler(at)gmail.com (ggtyler(at)gmail.com)>



Just looking for some second opinions and if anyone else has experienced this. 



Last week I spent 3 days doing spin and aerobatic training with Sergei Boriak in my Yak 52TW. Everything went great until the last flight of our third day. Doing a loop, just up near the top where you start to float over, the engine coughed and one or two seconds later coughed again.



We were at 2100 RPM and 29 Inches. Up near the top of the loop we were just getting into a misty cloud layer. Carb heat was not on. 



It most definitely felt like fuel starvation. I'm familiar with mag issues, and the airplane has all new mags and wires 10 hours ago. Was a definite cough, not a misfire. 



Similar experiences? Any ideas? Solutions?



Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=486255#486255







sp;      (And Get Some AWESOME FREE Gifts!)



http://www.matronics.com/contributp;                 -Matt Dralle, Libsp;     - The Yak-List Email Forum -



_-= Use the Matronics List Features Navigator to browse



http://www.matronics.com/Navigator?Yak-List



http://forums.matronics.c;         - NEW MATRONICS LIST WIKI -



http://wiki.matronics.com



http:=======

dsavarese0812(at)bellsout
Guest

Posted: Thu Dec 13, 2018 2:33 pm Post subject: Yak 52TW Fuel Starvation at near zero G

I donâ€™t know the answer to this situation on the CJ.  The 52 has a fuel junction below the front seat which has flapper valves on each end of the junction where the hoses from the left and right fuel tanks attach. The flapper valves are design to move inward or away from the fuel tank. Their purpose is to prevent fuel from moving from one tank to the other. HOWEVER, if one of the flapper valves were to bind or stick closed, it would prevent fuel from flowing into the fuel junction from that tank. Should this occur, one fuel tank could be completely emptied without the other tank ever draining a drop.  

Now if the  CJâ€™s header tank has anything similar to the 52â€™s fuel junction, a stuck or sticking flapper valve, it could definitely cause the symptom described. 

Dennis

Sent from my iPad

[quote] On Dec 13, 2018, at 3:32 PM, JON BLAKE <saber369(at)comcast.net> wrote:

 While we are on the subject of fuel flow, header tanks, etc.  I have a question about the CJ fuel system.

 Not long after I bought my CJ I was returning home from a full day of formation flying.  My CJ, not unlike many others, has an asymmetrical fuel feed issue meaning it drains from one tank more than the other based on trim or rather imbalanced trim.  On this day, as I neared home, the right tank had about 30 liters indicated and the left tank was approaching zero.   Just as I arrived at the initial entry point over the runway with the left fuel low light on steady for a few minutes, the engine quit.  While this sudden silence quickly got my attention, I wasn't all that worried because I was over the runway.  I entered a left bank planning to continue with a circling approach and land with the engine out, but then after about 3-5 seconds in the left bank the engine caught up and continued operating normally.  I landed immediately without any further issues. 

 Being an FNG to the CJ back then, I started calling some of the old timers asking their opinions.  All agreed that it was most likely a fuel issue, or lack of fuel on one side and as long as I had gas in both tanks I shouldn't experience any additional problems.  So, with ample gas in both tanks, I did several minutes of ground test runs at varying RPMs; high-speed taxi checks and after an hour or so took off and completed a successful test flight.  

 So the simple question is... Why did this happen?  I repeated the scenario a few years later; this time on purpose and over the long runway with the same results.  I replicated the same conditions with one exception... when the engine "quit" I delayed entering a turn for a few seconds (seemed like hours with all that quite in front of me) to see what would happen.  After a short delay, I entered the left bank and sure enough, the engine regained full RPM with no additional issues.  

 Why did this happen?  The main tanks feed the header tank, so in theory, the fuel tank with gas should continue to feed the header regardless - right?  I would think that the header tank, being center-line to the engine, would continue to drain fuel from the tank with gas and feed fuel to the engine regardless of any delta in fuel tank quantities.  

 After I repeated the incident on purpose, I once again called around for opinions and the one thing that I will remember and have passed on to FNGs is something Doug Sapp said... "There are a lot of CJs laying on their bellies in corn fields with 60 liters in one side and zero in the other."

 I know many will give opinions on the asymmetrical fuel flow, but that's not the question... the header tank is the question.  And for those who want to tell me about setting proper trim, I've got the trim tabs well balanced, but still have to "step on the fuller tank" to get it back to "30-30" in both tanks.  Help me understand the header tank thing and we can talk about trim later please.

 Jon Blake

 Saber369(at)comcast.net

> On December 13, 2018 at 12:59 PM Mark Davis <markdavis(at)wbsnet.org> wrote:

> 

> 

> 

> 

> What everyone is possibly not considering is that the flop tube is held in

> good fuel by either positive g or negative g.  O g where the issue arose

> could have the flop tube out of the fuel if sustained for a long enough time

> of the hose is becoming somewhat stiff.

> 

> Mark Davis

> N44K

> 

> 

> --

Saber369(at)comcast.net
Guest

Posted: Thu Dec 13, 2018 2:52 pm Post subject: Yak 52TW Fuel Starvation at near zero G

Thanks Dennis.



I'm thinking these "flapper" valves do not exist on the CJ.  I say this because when I part my CJ on a slope fuel will drain from the upslope tank to the down slope tank. 



Still leaving the question possed eariler about the header tank. JB

Sent from Xfinity Connect Application



--

pfstelwagon(at)earthlink.
Guest

Posted: Thu Dec 13, 2018 3:09 pm Post subject: Yak 52TW Fuel Starvation at near zero G

They are there they have to be looked at occasionally as they will stick open or closed. They get ignored because it is not easy to check them. They are not absolute like the air system check valves they will leak.



Frank



Sent from my iPhone



[quote] On Dec 13, 2018, at 2:51 PM, JON <Saber369(at)comcast.net> wrote:

 

 Thanks Dennis.

 

 I'm thinking these "flapper" valves do not exist on the CJ.  I say this because when I part my CJ on a slope fuel will drain from the upslope tank to the down slope tank. 

 

 Still leaving the question possed eariler about the header tank. JB

 

 

 Sent from Xfinity Connect Application

 

 --

pennington.construction.i
Guest

Posted: Thu Dec 13, 2018 3:58 pm Post subject: Yak 52TW Fuel Starvation at near zero G

What is the purpose of the valves in the header tank.

Could you remove them?



Mark Pennington



On Thu, Dec 13, 2018 at 6:15 PM Frank Stelwagon <pfstelwagon(at)earthlink.net>

wrote:



[quote] 

 >



 They are there they have to be looked at occasionally as they will stick

 open or closed. They get ignored because it is not easy to check them. They

 are not absolute like the air system check valves they will leak.



 Frank



 Sent from my iPhone



 > On Dec 13, 2018, at 2:51 PM, JON <Saber369(at)comcast.net> wrote:

 >

 > Thanks Dennis.

 >

 > I'm thinking these "flapper" valves do not exist on the CJ.  I say this

 because when I part my CJ on a slope fuel will drain from the upslope tank

 to the down slope tank.

 >

 > Still leaving the question possed eariler about the header tank. JB

 >

 >

 > Sent from Xfinity Connect Application

 >

 > --

pfstelwagon(at)earthlink.
Guest

Posted: Thu Dec 13, 2018 4:08 pm Post subject: Yak 52TW Fuel Starvation at near zero G

They are there to prevent cross feeding, not always successfully.  I wouldnâ€™t remove them.

Frank

Sent from my iPhone

On Dec 13, 2018, at 3:57 PM, Mark Pennington <pennington.construction.inc.1(at)gmail.com (pennington.construction.inc.1(at)gmail.com)> wrote:

[quote]What is the purpose of the valves in the header tank. 

Could you remove them?

Mark Pennington

On Thu, Dec 13, 2018 at 6:15 PM Frank Stelwagon <pfstelwagon(at)earthlink.net (pfstelwagon(at)earthlink.net)> wrote:

[quote]--> Yak-List message posted by: Frank Stelwagon <pfstelwagon(at)earthlink.net (pfstelwagon(at)earthlink.net)>

 They are there they have to be looked at occasionally as they will stick open or closed. They get ignored because it is not easy to check them. They are not absolute like the air system check valves they will leak.

 Frank

 Sent from my iPhone

 > On Dec 13, 2018, at 2:51 PM, JON <Saber369(at)comcast.net (Saber369(at)comcast.net)> wrote:

 > 

 > Thanks Dennis.

 > 

 > I'm thinking these "flapper" valves do not exist on the CJ.  I say this because when I part my CJ on a slope fuel will drain from the upslope tank to the down slope tank. 

 > 

 > Still leaving the question possed eariler about the header tank. JB

 > 

 > 

 > Sent from Xfinity Connect Application

 > 

 > --

bwade154(at)yahoo.com
Guest

Posted: Thu Dec 13, 2018 5:15 pm Post subject: Yak 52TW Fuel Starvation at near zero G

I would have to say the valves are there (in a Yak) to prevent fuel in the header tank from flowing to the wing tanks when inverted.

                  

                                                                    On â€ŽThursdayâ€Ž, â€ŽDecemberâ€Ž â€Ž13â€Ž, â€Ž2018â€Ž â€Ž07â€Ž:â€Ž20â€Ž:â€Ž10â€Ž â€ŽPMâ€Ž â€ŽEST, Frank Stelwagon <pfstelwagon(at)earthlink.net> wrote:                 

                 



                 



                 They are there to prevent cross feeding, not always successfully.  I wouldnâ€™t remove them.

FrankSent from my iPhone

On Dec 13, 2018, at 3:57 PM, Mark Pennington <pennington.construction.inc.1(at)gmail.com (pennington.construction.inc.1(at)gmail.com)> wrote:

[quote]What is the purpose of the valves in the header tank. 



Could you remove them?



Mark Pennington

On Thu, Dec 13, 2018 at 6:15 PM Frank Stelwagon <pfstelwagon(at)earthlink.net (pfstelwagon(at)earthlink.net)> wrote:

[quote]--> Yak-List message posted by: Frank Stelwagon <pfstelwagon(at)earthlink.net (pfstelwagon(at)earthlink.net)>  They are there they have to be looked at occasionally as they will stick open or closed. They get ignored because it is not easy to check them. They are not absolute like the air system check valves they will leak.  Frank  Sent from my iPhone  > On Dec 13, 2018, at 2:51 PM, JON <Saber369(at)comcast.net (Saber369(at)comcast.net)> wrote: >  > Thanks Dennis. >  > I'm thinking these "flapper" valves do not exist on the CJ.  I say this because when I part my CJ on a slope fuel will drain from the upslope tank to the down slope tank.  >  > Still leaving the question possed eariler about the header tank. JB >  >  > Sent from Xfinity Connect Application >  > --

pfstelwagon(at)earthlink.
Guest

Posted: Fri Dec 14, 2018 3:43 am Post subject: Yak 52TW Fuel Starvation at near zero G

That is also true.



Sent from my iPhone



On Dec 13, 2018, at 5:14 PM, bill wade <bwade154(at)yahoo.com (bwade154(at)yahoo.com)> wrote:

[quote]

         I would have to say the valves are there (in a Yak) to prevent fuel in the header tank from flowing to the wing tanks when inverted.

                  

                                                                    On â€ŽThursdayâ€Ž, â€ŽDecemberâ€Ž â€Ž13â€Ž, â€Ž2018â€Ž â€Ž07â€Ž:â€Ž20â€Ž:â€Ž10â€Ž â€ŽPMâ€Ž â€ŽEST, Frank Stelwagon <pfstelwagon(at)earthlink.net (pfstelwagon(at)earthlink.net)> wrote:                 

                 



                 



                 They are there to prevent cross feeding, not always successfully.  I wouldnâ€™t remove them.

FrankSent from my iPhone

On Dec 13, 2018, at 3:57 PM, Mark Pennington <pennington.construction.inc.1(at)gmail.com (pennington.construction.inc.1(at)gmail.com)> wrote:

[quote]What is the purpose of the valves in the header tank. 



Could you remove them?



Mark Pennington

On Thu, Dec 13, 2018 at 6:15 PM Frank Stelwagon <pfstelwagon(at)earthlink.net (pfstelwagon(at)earthlink.net)> wrote:

[quote]--> Yak-List message posted by: Frank Stelwagon <pfstelwagon(at)earthlink.net (pfstelwagon(at)earthlink.net)>  They are there they have to be looked at occasionally as they will stick open or closed. They get ignored because it is not easy to check them. They are not absolute like the air system check valves they will leak.  Frank  Sent from my iPhone  > On Dec 13, 2018, at 2:51 PM, JON <Saber369(at)comcast.net (Saber369(at)comcast.net)> wrote: >  > Thanks Dennis. >  > I'm thinking these "flapper" valves do not exist on the CJ.  I say this because when I part my CJ on a slope fuel will drain from the upslope tank to the down slope tank.  >  > Still leaving the question possed eariler about the header tank. JB >  >  > Sent from Xfinity Connect Application >  > --

Ttail

Joined: 24 Jun 2013
Posts: 118

Posted: Fri Dec 14, 2018 11:59 am Post subject: Re: Yak 52TW Fuel Starvation at near zero G

Does anyone have an image of the exact location of the flapper valves in the CJ or even an image of the flapper valve itself ?

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