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johnrobertnolan(at)gmail.
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 Posted: Mon Jan 07, 2019 2:03 pm Post subject: Fuel Imbalance (Re: Yak 52TW Fuel Starvation at near zero G |
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Dennis,
Can these be installed on your aftermarket fuel bladders?
John Nolan
On Sat, Dec 15, 2018 at 6:42 AM A. Dennis Savarese <
dsavarese0812(at)bellsouth.net> wrote:
[quote] FWIW, the single vent system Yak 52's (pre '89) models have a fuel
imbalance issue as well, especially with full tanks and with the airplane
sitting on the ramp in the sun. The net of it is the vent system gets
blocked with fuel. Particularly the vent line on the right tank because of
the design of the vent system. As everyone knows, vent lines must be clear
of fuel in order for fuel to feed. With a blocked vent line, no fuel can
feed from that tank. That's why we roll the airplane up on one wing and
fly straight to force the fuel out of the vent line.
BUT there is a solution...a second vent to the tank. This can also apply
to the CJ. Install this vent check valve on the top of the tank and run
the vent tube overboard. Most likely location is near the fill port so
you'll have access to the inside of the tank to tighten the nut on the
bottom of the vent check valve. The vent check valve is used in race cars
and should the race car were to turn over, the vent check valve would
prevent the fuel from leaking out of the tank. With the vent check valve
installed, during flight the tank will always have a clear vent line.
Here is a link to where it can be purchased and also a photo of the vent
check valve installed on the top of a fuel filler plate on a Yak 52 fuel
bladder. One is required for each fuel tank.
https://fuelsafe.com/thv45/
[image: Inline image]
[image: Inline image]
------------------------------
*From:* Greg Wrobel <clouddog22(at)gmail.com>
*To:* yak-list(at)matronics.com
*Sent:* Saturday, December 15, 2018 7:32 AM
*Subject:* Re: Re: Yak 52TW Fuel Starvation at near zero G
Regarding the CJ6. I was one of the fortunate to go to China with members
of the Southeast region a few months ago. The highlight of our 2 week
journey was visiting the factory that is currently building the latest CJ6A
aircraft (by the way, no significant changes were noted). I will not go
into the details of the visit or our journey but during our visit to the
factory, we were able to sit down with the factory manager , CJ6A
engineers, and production staff. When you ask a question , you do not want
to ask in a way that they preceive that you are accusing them of a design
flaw so our wording was carefully chosen. One of our questions related to
fuel imbalance so we carefully asked if they were aware of the fuel
imbalance that occures during flight or while sitting on a sloped ramp. To
our amazement, they were familiar. To our further amazement, nothing has
been done to correct the issue! They know it exist but there has been no
changes in design to correct it.
Please realize, our discussions were through interpreters as the only
Chinese we knew were PÃjiÇ” (beer) and BáijiÇ” (clear types of alchohol)
pronounced pee-joe and bye-joe respectively. Ok then, you have now been
enlightened to some important Chinese words of the day. In any case, we
are not sure if they truly understood our question or we truly understood
their answer but there you have it.
Now what does this have to do with engine hesitation at the top of a loop
in a YAK52.....absolutely nothing! Just seems we were beating flapper
valves to death in a CJ and went astray. We have installed elaborate
venting systems in our CJ's to fix fuel imbalance and have all these
questions and theories. Maybe the Chinese are telling the truth on this
one. The CJ has a fuel imbalance issue created by flappers/ check valves
or gremlins and apparently it is not going away. From my personal
expierence, I keep the fuel 3/4" - 1" below the rear lip of the fill port
as mentioned in the Chinese Flight Manual. This equates to 1 gallon less in
the tanks versus topping it off. Also attempting to fly wings level and in
trim (thats a full time, max concentration effort for me by the way) and
most of the time, my fuel burns symmetrical but not always. Apparently I'm
not concentrating hard enough. Darn flapper valves or are they flipper
valves? Who knows!
On Fri, Dec 14, 2018, 16:07 Walter Lannon <wlannon(at)shaw.ca wrote:
A few thoughts on fuel flow problems in the CJ;
Dennis, would I be correct in assuming that each flapper valve outlet of
the
fuel junction would go to the corresponding side of the Yak 52 header tank?
If so that is functionally the same as the CJ where the flapper valves are
mounted in the header tank walls.
In the early CJ days there were numerous problems with flapper valves stuck
closed due to evaporating Chinese fuel effectively gluing them in place.
Probably could repeat with auto gas and long enough storage time. Have not
heard of any such problem here with avgas.
Also many problems of blocked (or partially blocked) fuel and vent lines
due
dead bugs and debris. Many had sat for years after being discarded at or
near their 4000 hr. life limit.
Dented, kinked and otherwise damaged fuel and vent lines also contribute
immensely to unequal fuel flow.
On flapper valves; There are 3 of these in the CJ. One is mounted in the
line from the header tank to the fuel pump for the sole purpose
of preventing back flow of wobble pump fuel which would otherwise just
re-circulate through the wobble pump. It is subject to substantial opening
pressure from the wobble pump. Even Chinese fuel glue could not keep it
closed. An excellent design for the application.
The other two are identical but are used in an application that requires a
slightly different design which moves with fuel flow at minimal
differential
pressure. These are designed to require a significantly higher
differential
pressure to open (significantly here is a relative term, if one could
measure the pressures involved it would likely be in milligrams/sq. cm. )
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dsavarese0812(at)bellsout
Guest
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| Posted: Mon Jan 07, 2019 8:13 pm Post subject: Fuel Imbalance (Re: Yak 52TW Fuel Starvation at near zero G |
|
|
Fuel bladders are no longer available. If you have them, yes they can be installed in the filler plate.
Dennis
Sent from my iPhone
[quote] On Jan 7, 2019, at 5:01 PM, John Nolan <johnrobertnolan(at)gmail.com> wrote:
Dennis,
Can these be installed on your aftermarket fuel bladders?
John Nolan
> On Sat, Dec 15, 2018 at 6:42 AM A. Dennis Savarese <dsavarese0812(at)bellsouth.net> wrote:
> FWIW, the single vent system Yak 52's (pre '89) models have a fuel imbalance issue as well, especially with full tanks and with the airplane sitting on the ramp in the sun. The net of it is the vent system gets blocked with fuel. Particularly the vent line on the right tank because of the design of the vent system. As everyone knows, vent lines must be clear of fuel in order for fuel to feed. With a blocked vent line, no fuel can feed from that tank. That's why we roll the airplane up on one wing and fly straight to force the fuel out of the vent line.
>
> BUT there is a solution...a second vent to the tank. This can also apply to the CJ. Install this vent check valve on the top of the tank and run the vent tube overboard. Most likely location is near the fill port so you'll have access to the inside of the tank to tighten the nut on the bottom of the vent check valve. The vent check valve is used in race cars and should the race car were to turn over, the vent check valve would prevent the fuel from leaking out of the tank. With the vent check valve installed, during flight the tank will always have a clear vent line.
>
> Here is a link to where it can be purchased and also a photo of the vent check valve installed on the top of a fuel filler plate on a Yak 52 fuel bladder. One is required for each fuel tank.
>
> https://fuelsafe.com/thv45/
>
> <Vent valve.JPG>
>
> <photo 2.JPG>
>
>
>
>
> From: Greg Wrobel <clouddog22(at)gmail.com>
> To: yak-list(at)matronics.com
> Sent: Saturday, December 15, 2018 7:32 AM
> Subject: Re: Re: Yak 52TW Fuel Starvation at near zero G
>
> Regarding the CJ6. I was one of the fortunate to go to China with members of the Southeast region a few months ago. The highlight of our 2 week journey was visiting the factory that is currently building the latest CJ6A aircraft (by the way, no significant changes were noted). I will not go into the details of the visit or our journey but during our visit to the factory, we were able to sit down with the factory manager , CJ6A engineers, and production staff. When you ask a question , you do not want to ask in a way that they preceive that you are accusing them of a design flaw so our wording was carefully chosen. One of our questions related to fuel imbalance so we carefully asked if they were aware of the fuel imbalance that occures during flight or while sitting on a sloped ramp. To our amazement, they were familiar. To our further amazement, nothing has been done to correct the issue! They know it exist but there has been no changes in design to correct it.
>
> Please realize, our discussions were through interpreters as the only Chinese we knew were PÃjiÇ” (beer) and BáijiÇ” (clear types of alchohol) pronounced pee-joe and bye-joe respectively. Ok then, you have now been enlightened to some important Chinese words of the day. In any case, we are not sure if they truly understood our question or we truly understood their answer but there you have it.
>
> Now what does this have to do with engine hesitation at the top of a loop in a YAK52.....absolutely nothing! Just seems we were beating flapper valves to death in a CJ and went astray. We have installed elaborate venting systems in our CJ's to fix fuel imbalance and have all these questions and theories. Maybe the Chinese are telling the truth on this one. The CJ has a fuel imbalance issue created by flappers/ check valves or gremlins and apparently it is not going away. From my personal expierence, I keep the fuel 3/4" - 1" below the rear lip of the fill port as mentioned in the Chinese Flight Manual. This equates to 1 gallon less in the tanks versus topping it off. Also attempting to fly wings level and in trim (thats a full time, max concentration effort for me by the way) and most of the time, my fuel burns symmetrical but not always. Apparently I'm not concentrating hard enough. Darn flapper valves or are they flipper valves? Who knows!
>
> On Fri, Dec 14, 2018, 16:07 Walter Lannon <wlannon(at)shaw.ca wrote:
> A few thoughts on fuel flow problems in the CJ;
>
> Dennis, would I be correct in assuming that each flapper valve outlet of the
> fuel junction would go to the corresponding side of the Yak 52 header tank?
> If so that is functionally the same as the CJ where the flapper valves are
> mounted in the header tank walls.
>
> In the early CJ days there were numerous problems with flapper valves stuck
> closed due to evaporating Chinese fuel effectively gluing them in place.
> Probably could repeat with auto gas and long enough storage time. Have not
> heard of any such problem here with avgas.
> Also many problems of blocked (or partially blocked) fuel and vent lines due
> dead bugs and debris. Many had sat for years after being discarded at or
> near their 4000 hr. life limit.
> Dented, kinked and otherwise damaged fuel and vent lines also contribute
> immensely to unequal fuel flow.
>
> On flapper valves; There are 3 of these in the CJ. One is mounted in the
> line from the header tank to the fuel pump for the sole purpose
> of preventing back flow of wobble pump fuel which would otherwise just
> re-circulate through the wobble pump. It is subject to substantial opening
> pressure from the wobble pump. Even Chinese fuel glue could not keep it
> closed. An excellent design for the application.
>
> The other two are identical but are used in an application that requires a
> slightly different design which moves with fuel flow at minimal differential
> pressure. These are designed to require a significantly higher differential
> pressure to open (significantly here is a relative term, if one could
> measure the pressures involved it would likely be in milligrams/sq. cm. ).
> This is evident on inspection:- the area of valve opening surface is about
> 1/4 that of the surface holding it closed.
> In theory, with perfect trim and absolutely no turbulence whatsoever this
> valve would require one full and one empty tank to open.
>
> So; I have modified the valves in mine by removing valve seat material to
> reduce the surface contact area from 100% to a near line contact. (actually,
> since this is a hand filing operation) about a 0.020' to 0.030" contact
> band. This allows the normal closing pressure to also react on the opening
> side of the flapper resulting in a much closer balance between opening and
> closing forces. See attached photos.
>
> I normally never see a fuel imbalance in excess of 2 to 4 lts. except when I
> try to do good slow (or point) rolls. In this case the valve flappers are
> are doing just that, flapping! After a few I see imbalance up to 15 lts.
> or so which returns to normal in a few minutes of level flight.
>
> The valves alone are not the whole problem, I can not stress how important
> the condition of the fuel and vent lines are. Both damage, internal
> contamination and leakage are critical. I have spent days during CJ
> restorations with a hose, hot water, dish washer soap and shop air getting
> crap out of the lines. If you are going to do this be sure both ends of all
> lines are disconnected. You don't want to blow up the the mains or header
> tank in the process.
>
> I had a good example of what a minor discrepancy can do to this fuel system.
> A few years back on about 1 hr. flight home checked fuel gauges and shocked
> to see a 20 + lt. imbalance. Checking the vent system I found one connector
> hose in the RH wing joint area had slipped off! (I had used all new hose
> but no clamps thinking they were tight enough). Dumb! But this relatively
> small vent pressure change made a huge difference to the entire fuel system.
>
> These valves (In Western terms normally called a vent valve) MUST be mounted
> with the flapper hinge at the top! This requirement is a problem for the
> Chinese valve as mounted in the header tank since it is threaded into a
> welded fitting on the tank wall with a sealing washer.
> So; Three things have have to come together at precisely the same time and
> place. The valve is at the top, the torque is correct and the sealing washer
> is exactly the right thickness. This of course is mission impossible.
>
> Enough for now.
> Walt
>
>
>
>
> --
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johnrobertnolan(at)gmail.
Guest
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| Posted: Tue Jan 08, 2019 7:36 am Post subject: Fuel Imbalance (Re: Yak 52TW Fuel Starvation at near zero G |
|
|
Dennis,
Yes, I have them. I didn’t know that you no longer sell them. What are my repair or replace my options if it ever comes to that?
Thanks,
John Nolan
Sent from my iPhone
On Jan 7, 2019, at 9:12 PM, Anthony Savarese <dsavarese0812(at)bellsouth.net (dsavarese0812(at)bellsouth.net)> wrote:
[quote]Fuel bladders are no longer available. If you have them, yes they can be installed in the filler plate. Dennis
Sent from my iPhone
On Jan 7, 2019, at 5:01 PM, John Nolan <johnrobertnolan(at)gmail.com (johnrobertnolan(at)gmail.com)> wrote:
[quote]Dennis,
Can these be installed on your aftermarket fuel bladders?
John Nolan
On Sat, Dec 15, 2018 at 6:42 AM A. Dennis Savarese <dsavarese0812(at)bellsouth.net (dsavarese0812(at)bellsouth.net)> wrote:
[quote]FWIW, the single vent system Yak 52's (pre '89) models have a fuel imbalance issue as well, especially with full tanks and with the airplane sitting on the ramp in the sun. The net of it is the vent system gets blocked with fuel. Particularly the vent line on the right tank because of the design of the vent system. As everyone knows, vent lines must be clear of fuel in order for fuel to feed. With a blocked vent line, no fuel can feed from that tank. That's why we roll the airplane up on one wing and fly straight to force the fuel out of the vent line.
BUT there is a solution...a second vent to the tank. This can also apply to the CJ. Install this vent check valve on the top of the tank and run the vent tube overboard. Most likely location is near the fill port so you'll have access to the inside of the tank to tighten the nut on the bottom of the vent check valve. The vent check valve is used in race cars and should the race car were to turn over, the vent check valve would prevent the fuel from leaking out of the tank. With the vent check valve installed, during flight the tank will always have a clear vent line.
Here is a link to where it can be purchased and also a photo of the vent check valve installed on the top of a fuel filler plate on a Yak 52 fuel bladder. One is required for each fuel tank.
https://fuelsafe.com/thv45/
<Vent valve.JPG>
<photo 2.JPG>
From: Greg Wrobel <clouddog22(at)gmail.com (clouddog22(at)gmail.com)>
To: yak-list(at)matronics.com (yak-list(at)matronics.com)
Sent: Saturday, December 15, 2018 7:32 AM
Subject: Re: Re: Yak 52TW Fuel Starvation at near zero G
Regarding the CJ6. I was one of the fortunate to go to China with members of the Southeast region a few months ago. The highlight of our 2 week journey was visiting the factory that is currently building the latest CJ6A aircraft (by the way, no significant changes were noted). I will not go into the details of the visit or our journey but during our visit to the factory, we were able to sit down with the factory manager , CJ6A engineers, and production staff. When you ask a question , you do not want to ask in a way that they preceive that you are accusing them of a design flaw so our wording was carefully chosen. One of our questions related to fuel imbalance so we carefully asked if they were aware of the fuel imbalance that occures during flight or while sitting on a sloped ramp. To our amazement, they were familiar. To our further amazement, nothing has been done to correct the issue! They know it exist but there has been no changes in design to correct it.
Please realize, our discussions were through interpreters as the only Chinese we knew were PÃjiÇ” (beer) and BáijiÇ” (clear types of alchohol) pronounced pee-joe and bye-joe respectively. Ok then, you have now been enlightened to some important Chinese words of the day. In any case, we are not sure if they truly understood our question or we truly understood their answer but there you have it.
Now what does this have to do with engine hesitation at the top of a loop in a YAK52.....absolutely nothing! Just seems we were beating flapper valves to death in a CJ and went astray. We have installed elaborate venting systems in our CJ's to fix fuel imbalance and have all these questions and theories. Maybe the Chinese are telling the truth on this one. The CJ has a fuel imbalance issue created by flappers/ check valves or gremlins and apparently it is not going away. From my personal expierence, I keep the fuel 3/4" - 1" below the rear lip of the fill port as mentioned in the Chinese Flight Manual. This equates to 1 gallon less in the tanks versus topping it off. Also attempting to fly wings level and in trim (thats a full time, max concentration effort for me by the way) and most of the time, my fuel burns symmetrical but not always. Apparently I'm not concentrating hard enough. Darn flapper valves or are they flipper valves? Who knows!
On Fri, Dec 14, 2018, 16:07 Walter Lannon <wlannon(at)shaw.ca (wlannon(at)shaw.ca) wrote:
[quote]A few thoughts on fuel flow problems in the CJ; Dennis, would I be correct in assuming that each flapper valve outlet of the fuel junction would go to the corresponding side of the Yak 52 header tank? If so that is functionally the same as the CJ where the flapper valves are mounted in the header tank walls. In the early CJ days there were numerous problems with flapper valves stuck closed due to evaporating Chinese fuel effectively gluing them in place. Probably could repeat with auto gas and long enough storage time. Have not heard of any such problem here with avgas. Also many problems of blocked (or partially blocked) fuel and vent lines due dead bugs and debris. Many had sat for years after being discarded at or near their 4000 hr. life limit. Dented, kinked and otherwise damaged fuel and vent lines also contribute immensely to unequal fuel flow. On flapper valves; There are 3 of these in the CJ. One is mounted in the line from the header tank to the fuel pump for the sole purpose of preventing back flow of wobble pump fuel which would otherwise just re-circulate through the wobble pump. It is subject to substantial opening pressure from the wobble pump. Even Chinese fuel glue could not keep it closed. An excellent design for the application. The other two are identical but are used in an application that requires a slightly different design which moves with fuel flow at minimal differential pressure. These are designed to require a significantly higher differential pressure to open (significantly here is a relative term, if one could measure the pressures involved it would likely be in milligrams/sq. cm. ). This is evident on inspection:- the area of valve opening surface is about 1/4 that of the surface holding it closed. In theory, with perfect trim and absolutely no turbulence whatsoever this valve would require one full and one empty tank to open. So; I have modified the valves in mine by removing valve seat material to reduce the surface contact area from 100% to a near line contact. (actually, since this is a hand filing operation) about a 0.020' to 0.030" contact band. This allows the normal closing pressure to also react on the opening side of the flapper resulting in a much closer balance between opening and closing forces. See attached photos. I normally never see a fuel imbalance in excess of 2 to 4 lts. except when I try to do good slow (or point) rolls. In this case the valve flappers are are doing just that, flapping! After a few I see imbalance up to 15 lts. or so which returns to normal in a few minutes of level flight. The valves alone are not the whole problem, I can not stress how important the condition of the fuel and vent lines are. Both damage, internal contamination and leakage are critical. I have spent days during CJ restorations with a hose, hot water, dish washer soap and shop air getting crap out of the lines. If you are going to do this be sure both ends of all lines are disconnected. You don't want to blow up the the mains or header tank in the process. I had a good example of what a minor discrepancy can do to this fuel system. A few years back on about 1 hr. flight home checked fuel gauges and shocked to see a 20 + lt. imbalance. Checking the vent system I found one connector hose in the RH wing joint area had slipped off! (I had used all new hose but no clamps thinking they were tight enough). Dumb! But this relatively small vent pressure change made a huge difference to the entire fuel system. These valves (In Western terms normally called a vent valve) MUST be mounted with the flapper hinge at the top! This requirement is a problem for the Chinese valve as mounted in the header tank since it is threaded into a welded fitting on the tank wall with a sealing washer. So; Three things have have to come together at precisely the same time and place. The valve is at the top, the torque is correct and the sealing washer is exactly the right thickness. This of course is mission impossible. Enough for now. Walt --
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dsavarese0812(at)bellsout
Guest
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| Posted: Tue Jan 08, 2019 12:46 pm Post subject: Fuel Imbalance (Re: Yak 52TW Fuel Starvation at near zero G |
|
|
Since April 2017.
If they ever needed repair, they could be shipped back to Aerotech in California, who manufactured them for us.
Dennis
Sent from my iPhone
[quote] On Jan 8, 2019, at 10:34 AM, John Nolan <johnrobertnolan(at)gmail.com> wrote:
Dennis,
Yes, I have them. I didn’t know that you no longer sell them. What are my repair or replace my options if it ever comes to that?
Thanks,
John Nolan
Sent from my iPhone
> On Jan 7, 2019, at 9:12 PM, Anthony Savarese <dsavarese0812(at)bellsouth.net> wrote:
>
> Fuel bladders are no longer available. If you have them, yes they can be installed in the filler plate.
> Dennis
>
> Sent from my iPhone
>
>> On Jan 7, 2019, at 5:01 PM, John Nolan <johnrobertnolan(at)gmail.com> wrote:
>>
>> Dennis,
>>
>> Can these be installed on your aftermarket fuel bladders?
>>
>> John Nolan
>>
>>> On Sat, Dec 15, 2018 at 6:42 AM A. Dennis Savarese <dsavarese0812(at)bellsouth.net> wrote:
>>> FWIW, the single vent system Yak 52's (pre '89) models have a fuel imbalance issue as well, especially with full tanks and with the airplane sitting on the ramp in the sun. The net of it is the vent system gets blocked with fuel. Particularly the vent line on the right tank because of the design of the vent system. As everyone knows, vent lines must be clear of fuel in order for fuel to feed. With a blocked vent line, no fuel can feed from that tank. That's why we roll the airplane up on one wing and fly straight to force the fuel out of the vent line.
>>>
>>> BUT there is a solution...a second vent to the tank. This can also apply to the CJ. Install this vent check valve on the top of the tank and run the vent tube overboard. Most likely location is near the fill port so you'll have access to the inside of the tank to tighten the nut on the bottom of the vent check valve. The vent check valve is used in race cars and should the race car were to turn over, the vent check valve would prevent the fuel from leaking out of the tank. With the vent check valve installed, during flight the tank will always have a clear vent line.
>>>
>>> Here is a link to where it can be purchased and also a photo of the vent check valve installed on the top of a fuel filler plate on a Yak 52 fuel bladder. One is required for each fuel tank.
>>>
>>> https://fuelsafe.com/thv45/
>>>
>>> <Vent valve.JPG>
>>>
>>> <photo 2.JPG>
>>>
>>>
>>>
>>>
>>> From: Greg Wrobel <clouddog22(at)gmail.com>
>>> To: yak-list(at)matronics.com
>>> Sent: Saturday, December 15, 2018 7:32 AM
>>> Subject: Re: Re: Yak 52TW Fuel Starvation at near zero G
>>>
>>> Regarding the CJ6. I was one of the fortunate to go to China with members of the Southeast region a few months ago. The highlight of our 2 week journey was visiting the factory that is currently building the latest CJ6A aircraft (by the way, no significant changes were noted). I will not go into the details of the visit or our journey but during our visit to the factory, we were able to sit down with the factory manager , CJ6A engineers, and production staff. When you ask a question , you do not want to ask in a way that they preceive that you are accusing them of a design flaw so our wording was carefully chosen. One of our questions related to fuel imbalance so we carefully asked if they were aware of the fuel imbalance that occures during flight or while sitting on a sloped ramp. To our amazement, they were familiar. To our further amazement, nothing has been done to correct the issue! They know it exist but there has been no changes in design to correct it.
>>>
>>> Please realize, our discussions were through interpreters as the only Chinese we knew were PÃjiÇ” (beer) and BáijiÇ” (clear types of alchohol) pronounced pee-joe and bye-joe respectively. Ok then, you have now been enlightened to some important Chinese words of the day. In any case, we are not sure if they truly understood our question or we truly understood their answer but there you have it.
>>>
>>> Now what does this have to do with engine hesitation at the top of a loop in a YAK52.....absolutely nothing! Just seems we were beating flapper valves to death in a CJ and went astray. We have installed elaborate venting systems in our CJ's to fix fuel imbalance and have all these questions and theories. Maybe the Chinese are telling the truth on this one. The CJ has a fuel imbalance issue created by flappers/ check valves or gremlins and apparently it is not going away. From my personal expierence, I keep the fuel 3/4" - 1" below the rear lip of the fill port as mentioned in the Chinese Flight Manual. This equates to 1 gallon less in the tanks versus topping it off. Also attempting to fly wings level and in trim (thats a full time, max concentration effort for me by the way) and most of the time, my fuel burns symmetrical but not always. Apparently I'm not concentrating hard enough. Darn flapper valves or are they flipper valves? Who knows!
>>>
>>> On Fri, Dec 14, 2018, 16:07 Walter Lannon <wlannon(at)shaw.ca wrote:
>>> A few thoughts on fuel flow problems in the CJ;
>>>
>>> Dennis, would I be correct in assuming that each flapper valve outlet of the
>>> fuel junction would go to the corresponding side of the Yak 52 header tank?
>>> If so that is functionally the same as the CJ where the flapper valves are
>>> mounted in the header tank walls.
>>>
>>> In the early CJ days there were numerous problems with flapper valves stuck
>>> closed due to evaporating Chinese fuel effectively gluing them in place
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