Today's Message Index:
----------------------
1. 05:46 AM - Re: Re: Pressure Problem (A. Dennis Savarese)
2. 05:55 AM - Re: Re: Pressure Problem (A. Dennis Savarese)
3. 06:39 AM - Re: Pressure Problem (keithmckinley)
4. 07:03 AM - Re: Pressure Problem (Bill1200)
5. 07:18 AM - Re: Re: Pressure Problem (Bitterlich, Mark G CIV NAVAIR, WD)
6. 01:41 PM - Re: Pressure Problem (keithmckinley)
Message 1
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| Subject: | Re: Pressure Problem |
However, with the main air off and the gear selector in neutral, don't
forget to depressurize the systemby squeezing the brake handle until no
"swoosh" is heard, which releases the emergency air pressure on the
actuator shuttle valves. If you don't do this and you try to go back to
the main air system and cycle the gear, thegear will lock into position
up or downbecause the emergency air pressure is holding the gear down.
Dennis
A. Dennis Savarese
334-285-6263
334-546-8182 (mobile)
www.yak-52.com
Skype - Yakguy1
On 6/25/2014 4:13 PM, Bitterlich, Mark G CIV NAVAIR, WD wrote:
>
> Thanks for the compliment Ernie.
>
> Let me add a tad more to the landing gear handle issue to be just a little more
clear.
>
> When the gear handle is in the middle, NO AIR PRESSURE AT ALL is fed to EITHER
side of the landing gear actuators. They are totally isolated from the rest
of the pneumatic system.
>
> However, the vent is NOT closed in the middle. The vent is in fact open, and
there should then be no high pressure on either side of the actuators.
>
> This then carries us to how this knowledge might be used in an emergency.
>
> In the YAK-52, the emergency air bottle is not pressurized from the engine compressor.
By the way, on the YAK-50 it is! In any case, with the YAK-52, the
emergency bottle is a one shot deal.
>
> Moving on..... If for some reason you had a massive actuator leak and could
not get the gear down, and you used the emergency bottle and still had an issue,
if you then left the gear handle in the middle, the engine air compressor
would then re-pressurize the MAIN bottle to 50 ATM (about 735 PSI) and you could
then once AGAIN put the gear handle to the DOWN position, you would have no
"back pressure" buffer and thus you would have another chance to get the gear
down. This cycle could be repeated several times. This tidbit is not contained
in any of the emergency operating procedures for either the YAK-50 or 52,
but it is factual and something to store away and hopefully never have to use.
>
> Mark
>
>
> -----Original Message-----
> From: owner-yak-list-server@matronics.com [mailto:owner-yak-list-server@matronics.com] On Behalf Of Ernest Martinez
> Sent: Wednesday, June 25, 2014 3:50 PM
> To: yak-list
> Subject: Re: Yak-List: Re: Pressure Problem
>
> This is why I posed the question.
>
> Marks excellent explanation states that the vent is open when the gear is in
the up, or down position in order to allow the "Opposite" side to vent. When in
neutral, the vent is closed. So that logic dictates that the in the up position,
the down side is being vented, so there is no back pressure to cushion the
actuator.
>
> Ernie
>
>
> On Wed, Jun 25, 2014 at 3:38 PM, A. Dennis Savarese <dsavarese0812@bellsouth.net>
wrote:
>
>
> Because you have completely depressurized the actuators with the selector in
neutral. During normal operation, the air pressure on the UP side of the actuator
acts like a "cushion" because when you put the gear selector to the DOWN
position (the air pressure is pushing the gear down), the UP side of the actuator
is depressurizing. That is what you hear coming out of the gear selector.
With no pressure on the UP side, there is nothing to hold it back and thus
the gear slams down.
>
> A. Dennis Savarese
> 334-285-6263
> 334-546-8182 (mobile)
> www.yak-52.com
> Skype - Yakguy1
> On 6/25/2014 11:54 AM, Ernest Martinez wrote:
>
>
> Why then does the gear slam down if the selector is left in neutral?
>
> Ernie
>
>
> On Wed, Jun 25, 2014 at 12:48 PM, doug sapp <dougsappllc@gmail.com> wrote:
>
>
> Mark,
> Great post and explanation of how the system works, much better than I could
have done myself. 100% spot on.
>
> Doug
>
>
> On Wed, Jun 25, 2014 at 9:10 AM, Bitterlich, Mark G CIV NAVAIR, WD <mark.bitterlich@navy.mil>
wrote:
>
>
>
> Actually Keith, the gear selector in the YAK is something you really need
to know in detail. When I first got my 50, I noticed that the gear handle "had
a leak". I removed it from the aircraft, took it all apart, and there was
not a darn thing wrong with it. This was about 14 years ago.
>
> I reverse engineered every single air-line in that darn thing and finally
figured it out, which it today pretty much common knowledge.
>
> You're right about the port but it is important to know that the air you
hear venting is coming from the OPPOSITE SIDE of the actuators that you are trying
to pressurize. In other words, picture this: If you have an actuator and
push on it in one direction, the internal plunger is going to push air OUT the
other side! And that air has to go SOMEPLACE and that "someplace" is out
the vent you are talking about.
>
> So when you put the gear handle DOWN, air goes in and forces the actuators
to move. The air on the OPPOSITE side of that piston is then pushed out of
the actuator, up through the air lines, to the gear actuator and out the vent.
>
> An important things to realize about this.
>
> The actuators are internally sealed (in the YAK-50) with rubber Chevron Seals.
These can fail, meaning they will leak. This is of course a very bad
thing and needs to be corrected immediately. How do you know it is happening?
Because when the gear goes down (or up) and the handle is left in that position,
air pressure is constantly fed to the piston in the actuator. If the internal
seals leak, the air will come out the opposite side of the actuator, go
up the air-lines to the gear actuator handle and HISS out of the vent port constantly.
This can leak you to believe you have a bad gear actuator selector
when in fact you have a serious problem in your gear actuator(s)!
>
> So bottom line, if you hear air hissing out of the gear actuator lever in
the cockpit, do not immediately assume there is a leak in the gear selector,
instead check to see if it is coming out of the VENT in which case, suspect a
leaking gear actuator seal.
>
> Mark
>
>
>
> -----Original Message-----
> From: owner-yak-list-server@matronics.com [mailto:owner-yak-list-server@matronics.com] On Behalf Of keithmckinley
> Sent: Wednesday, June 25, 2014 9:30 AM
> To: yak-list@matronics.com
> Subject: Yak-List: Re: Pressure Problem
>
>
> The gear and flap selector valve has a small port that will vent air when
the selector is moved from one position to the other. I've had one of these selector
valves leak so bad through this port I could not build full pressure.
> If you have started playing with the ones in the rear cockpit you may start
there.
>
> Mine was a CJ and I believe the selectors are the same in a Yak
>
> --------
> Keith McKinley
> 700HS
> X26 Sebastian, FL
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=425447#425447
>
>
>
>
>
>
>
>
>
>
>
>
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> target="_blank">http://www.matronics.com/Navigator?Yak-List
> ==========
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> tp://forums.matronics.com
> _blank">http://www.matronics.com/contribution
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Message 2
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| Subject: | Re: Pressure Problem |
I should have said will NOT lock into position. Sorry.
A. Dennis Savarese
334-285-6263
334-546-8182 (mobile)
www.yak-52.com
Skype - Yakguy1
On 6/26/2014 7:46 AM, A. Dennis Savarese wrote:
> However, with the main air off and the gear selector in neutral, don't
> forget to depressurize the systemby squeezing the brake handle until
> no "swoosh" is heard, which releases the emergency air pressure on the
> actuator shuttle valves. If you don't do this and you try to go back
> to the main air system and cycle the gear, thegear will lock into
> position up or downbecause the emergency air pressure is holding the
> gear down.
> Dennis
> A. Dennis Savarese
> 334-285-6263
> 334-546-8182 (mobile)
> www.yak-52.com
> Skype - Yakguy1
> On 6/25/2014 4:13 PM, Bitterlich, Mark G CIV NAVAIR, WD wrote:
>>
>> Thanks for the compliment Ernie.
>>
>> Let me add a tad more to the landing gear handle issue to be just a little more
clear.
>>
>> When the gear handle is in the middle, NO AIR PRESSURE AT ALL is fed to EITHER
side of the landing gear actuators. They are totally isolated from the rest
of the pneumatic system.
>>
>> However, the vent is NOT closed in the middle. The vent is in fact open, and
there should then be no high pressure on either side of the actuators.
>>
>> This then carries us to how this knowledge might be used in an emergency.
>>
>> In the YAK-52, the emergency air bottle is not pressurized from the engine compressor.
By the way, on the YAK-50 it is! In any case, with the YAK-52,
the emergency bottle is a one shot deal.
>>
>> Moving on..... If for some reason you had a massive actuator leak and could
not get the gear down, and you used the emergency bottle and still had an issue,
if you then left the gear handle in the middle, the engine air compressor
would then re-pressurize the MAIN bottle to 50 ATM (about 735 PSI) and you could
then once AGAIN put the gear handle to the DOWN position, you would have no
"back pressure" buffer and thus you would have another chance to get the gear
down. This cycle could be repeated several times. This tidbit is not contained
in any of the emergency operating procedures for either the YAK-50 or 52,
but it is factual and something to store away and hopefully never have to use.
>>
>> Mark
>>
>>
>> -----Original Message-----
>> From:owner-yak-list-server@matronics.com [mailto:owner-yak-list-server@matronics.com] On Behalf Of Ernest Martinez
>> Sent: Wednesday, June 25, 2014 3:50 PM
>> To: yak-list
>> Subject: Re: Yak-List: Re: Pressure Problem
>>
>> This is why I posed the question.
>>
>> Marks excellent explanation states that the vent is open when the gear is in
the up, or down position in order to allow the "Opposite" side to vent. When
in neutral, the vent is closed. So that logic dictates that the in the up position,
the down side is being vented, so there is no back pressure to cushion the
actuator.
>>
>> Ernie
>>
>>
>> On Wed, Jun 25, 2014 at 3:38 PM, A. Dennis Savarese<dsavarese0812@bellsouth.net>
wrote:
>>
>>
>> Because you have completely depressurized the actuators with the selector in
neutral. During normal operation, the air pressure on the UP side of the actuator
acts like a "cushion" because when you put the gear selector to the DOWN
position (the air pressure is pushing the gear down), the UP side of the actuator
is depressurizing. That is what you hear coming out of the gear selector.
With no pressure on the UP side, there is nothing to hold it back and thus
the gear slams down.
>>
>> A. Dennis Savarese
>> 334-285-6263
>> 334-546-8182 (mobile)
>> www.yak-52.com
>> Skype - Yakguy1
>> On 6/25/2014 11:54 AM, Ernest Martinez wrote:
>>
>>
>> Why then does the gear slam down if the selector is left in neutral?
>>
>> Ernie
>>
>>
>> On Wed, Jun 25, 2014 at 12:48 PM, doug sapp<dougsappllc@gmail.com> wrote:
>>
>>
>> Mark,
>> Great post and explanation of how the system works, much better than I could
have done myself. 100% spot on.
>>
>> Doug
>>
>>
>> On Wed, Jun 25, 2014 at 9:10 AM, Bitterlich, Mark G CIV NAVAIR, WD<mark.bitterlich@navy.mil>
wrote:
>>
>>
>>
>> Actually Keith, the gear selector in the YAK is something you really need
to know in detail. When I first got my 50, I noticed that the gear handle
"had a leak". I removed it from the aircraft, took it all apart, and there was
not a darn thing wrong with it. This was about 14 years ago.
>>
>> I reverse engineered every single air-line in that darn thing and finally
figured it out, which it today pretty much common knowledge.
>>
>> You're right about the port but it is important to know that the air you
hear venting is coming from the OPPOSITE SIDE of the actuators that you are trying
to pressurize. In other words, picture this: If you have an actuator and
push on it in one direction, the internal plunger is going to push air OUT
the other side! And that air has to go SOMEPLACE and that "someplace" is out
the vent you are talking about.
>>
>> So when you put the gear handle DOWN, air goes in and forces the actuators
to move. The air on the OPPOSITE side of that piston is then pushed out of
the actuator, up through the air lines, to the gear actuator and out the vent.
>>
>> An important things to realize about this.
>>
>> The actuators are internally sealed (in the YAK-50) with rubber Chevron
Seals. These can fail, meaning they will leak. This is of course a very bad
thing and needs to be corrected immediately. How do you know it is happening?
Because when the gear goes down (or up) and the handle is left in that position,
air pressure is constantly fed to the piston in the actuator. If the
internal seals leak, the air will come out the opposite side of the actuator,
go up the air-lines to the gear actuator handle and HISS out of the vent port
constantly. This can leak you to believe you have a bad gear actuator selector
when in fact you have a serious problem in your gear actuator(s)!
>>
>> So bottom line, if you hear air hissing out of the gear actuator lever in
the cockpit, do not immediately assume there is a leak in the gear selector,
instead check to see if it is coming out of the VENT in which case, suspect a
leaking gear actuator seal.
>>
>> Mark
>>
>>
>>
>> -----Original Message-----
>> From:owner-yak-list-server@matronics.com [mailto:owner-yak-list-server@matronics.com] On Behalf Of keithmckinley
>> Sent: Wednesday, June 25, 2014 9:30 AM
>> To:yak-list@matronics.com
>> Subject: Yak-List: Re: Pressure Problem
>>
>>
>> The gear and flap selector valve has a small port that will vent air when
the selector is moved from one position to the other. I've had one of these
selector valves leak so bad through this port I could not build full pressure.
>> If you have started playing with the ones in the rear cockpit you may start
there.
>>
>> Mine was a CJ and I believe the selectors are the same in a Yak
>>
>> --------
>> Keith McKinley
>> 700HS
>> X26 Sebastian, FL
>>
>>
>>
>>
>> Read this topic online here:
>>
>> http://forums.matronics.com/viewtopic.php?p=425447#425447
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> ==========
>> target="_blank">http://www.matronics.com/Navigator?Yak-List
>> ==========
>> MS -
>> k">http://forums.matronics.com
>> ==========
>> e -
>> -Matt Dralle, List Admin.
>> t="_blank">http://www.matronics.com/contribution
>> ==========
>>
>>
>>
>>
>>
>>
>>
>>
>> et="_blank">http://www.matronics.com/Navigator?Yak-List
>> tp://forums.matronics.com
>> _blank">http://www.matronics.com/contribution
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> et="_blank">http://www.matronics.com/Navigator?Yak-List
>> tp://forums.matronics.com
>> _blank">http://www.matronics.com/contribution
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>
> *
>
>
> *
Message 3
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| Subject: | Re: Pressure Problem |
Another thing I found when I was having issues was that the air was leaking out
of the front selector valve but it was due to a bad rear valve......
--------
Keith McKinley
700HS
X26 Sebastian, FL
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=425537#425537
Message 4
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| Subject: | Re: Pressure Problem |
UPDATE:
Nose wheel actuator is the problem.
Tested per instructions here. Plane on jacks, gear up, didn't need U/S detector,
fairly big air leak from top of nose wheel actuator.
Sent for seal kit from M14P
Until repair, plan on flying with gear handle in neutral. Understand, to put it
back in gear up position before gear down prior to landing.
Thanks to all again.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=425540#425540
Message 5
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| Subject: | Re: Pressure Problem |
Well darn, that most definitely sucks!
In the "For what it is worth" category, I do not own a YAK-52 (can't fit), and
am not up to speed on all the complexities of the dual pneumatic controls in
that thing. See Dennis for expert explanations. The Yak-50 has no flaps, and
mine has no air brakes (been converted to Cleveland wheels with standard hydraulic
toe brakes), so comments from me regarding 52's are not based on experience
but instead "converted knowledge" learned from my 50 ... which once in a
while has bit me in the tail because there are some real differences. An example
is the locking ball system in the 52's gear actuators as compared to an
external locking wedge system in the 50's down and lock design. Based on what
you just said here.... I think I like mine better. :-) Whew... glad no one
was hurt.
Mark
-----Original Message-----
From: owner-yak-list-server@matronics.com [mailto:owner-yak-list-server@matronics.com] On Behalf Of Jeff Hove
Sent: Thursday, June 26, 2014 12:10 AM
Subject: Re: Yak-List: Re: Pressure Problem
Great description Mark.
Now for bonus points (I have not seen this mentioned before and everyone should
know this):
What happens if on the ground (gear down, engine off) you hear hissing from
the rear gear selector then, suspecting a leaky valve, you wiggle it and find
that lifting the rear selector just barely out of it's down detent but still
"down" stops the hissing? Problem solved!
Then to start repairs, you evacuate the air system (by dropping the flaps
and pumping the brake, or opening a fitting).
The result is (scroll down after you've thought this through a bit) ...
Gear collapse!
Even though the gear selector is still basically "down" and the safety slide still
in place, internally the valve has blocked the vent allowing the gear-up-side
pressure to release. The leaky cylinder seal allowed the gear-up side of
the cylinders to slowly achieve equal pressure but that trapped air does not release
as quickly as the gear-down pressure
releases when you evacuate the system. Once the gear-down pressure is
reduced, the gear-up side wins the fight.
We've all seen these type of aircraft sit just fine on their gear with depleted
air tanks. The ball-lock mechanisms in the actuators lock the gear down without
needing pressure. But a bit of residual pressure trapped on the wrong side
can be disastrous.
I hope this helps others avoid that fate.
Jeff Hove
Reluctant witness
On 6/25/2014 11:10 AM, Bitterlich, Mark G CIV NAVAIR, WD wrote:
> --> <mark.bitterlich@navy.mil>
>
> Actually Keith, the gear selector in the YAK is something you really need to
know in detail. When I first got my 50, I noticed that the gear handle "had
a leak". I removed it from the aircraft, took it all apart, and there was not
a darn thing wrong with it. This was about 14 years ago.
>
> I reverse engineered every single air-line in that darn thing and finally figured
it out, which it today pretty much common knowledge.
>
> You're right about the port but it is important to know that the air you hear
venting is coming from the OPPOSITE SIDE of the actuators that you are trying
to pressurize. In other words, picture this: If you have an actuator and push
on it in one direction, the internal plunger is going to push air OUT the other
side! And that air has to go SOMEPLACE and that "someplace" is out the
vent you are talking about.
>
> So when you put the gear handle DOWN, air goes in and forces the actuators to
move. The air on the OPPOSITE side of that piston is then pushed out of the
actuator, up through the air lines, to the gear actuator and out the vent.
>
> An important things to realize about this.
>
> The actuators are internally sealed (in the YAK-50) with rubber Chevron Seals.
These can fail, meaning they will leak. This is of course a very bad thing
and needs to be corrected immediately. How do you know it is happening?
Because when the gear goes down (or up) and the handle is left in that position,
air pressure is constantly fed to the piston in the actuator. If the internal
seals leak, the air will come out the opposite side of the actuator, go up
the air-lines to the gear actuator handle and HISS out of the vent port constantly.
This can leak you to believe you have a bad gear actuator selector when
in fact you have a serious problem in your gear actuator(s)!
>
> So bottom line, if you hear air hissing out of the gear actuator lever in the
cockpit, do not immediately assume there is a leak in the gear selector, instead
check to see if it is coming out of the VENT in which case, suspect a leaking
gear actuator seal.
>
> Mark
>
>
> -----Original Message-----
> From: owner-yak-list-server@matronics.com
> [mailto:owner-yak-list-server@matronics.com] On Behalf Of
> keithmckinley
> Sent: Wednesday, June 25, 2014 9:30 AM
> To: yak-list@matronics.com
> Subject: Yak-List: Re: Pressure Problem
>
>
> The gear and flap selector valve has a small port that will vent air when the
selector is moved from one position to the other. I've had one of these selector
valves leak so bad through this port I could not build full pressure.
> If you have started playing with the ones in the rear cockpit you may start there.
>
> Mine was a CJ and I believe the selectors are the same in a Yak
>
> --------
> Keith McKinley
> 700HS
> X26 Sebastian, FL
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=425447#425447
>
>
Message 6
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| Subject: | Re: Pressure Problem |
A lot of times we have these long maintenance threads but the original poster never
shares the results. Thanks for posting the results of your troubleshooting!
Keith
--------
Keith McKinley
700HS
X26 Sebastian, FL
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=425563#425563
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