Today's Message Index:
----------------------
1. 05:19 AM - Re: Pressure Problem (A. Dennis Savarese)
2. 06:30 AM - Re: Pressure Problem (keithmckinley)
3. 06:39 AM - Re: Re: Pressure Problem (A. Dennis Savarese)
4. 07:47 AM - Re: Pressure Problem (Bitterlich, Mark G CIV NAVAIR, WD)
5. 09:11 AM - Re: Re: Pressure Problem (Bitterlich, Mark G CIV NAVAIR, WD)
6. 09:48 AM - Re: Re: Pressure Problem (doug sapp)
7. 09:55 AM - Re: Re: Pressure Problem (Ernest Martinez)
8. 10:37 AM - CJ Dimensions (Ernest Martinez)
9. 11:19 AM - Re: CJ Dimensions (Richard Hess)
10. 11:30 AM - Re: CJ Dimensions (jblake207@comcast.net)
11. 11:35 AM - Re: Re: Pressure Problem (Bitterlich, Mark G CIV NAVAIR, WD)
12. 12:03 PM - Re: Re: Pressure Problem (doug sapp)
13. 12:05 PM - Re: Re: Pressure Problem (cjpilot710@aol.com)
14. 12:38 PM - Re: Re: Pressure Problem (A. Dennis Savarese)
15. 12:40 PM - Re: Re: Pressure Problem (A. Dennis Savarese)
16. 12:50 PM - Re: Re: Pressure Problem (Ernest Martinez)
17. 02:13 PM - Re: Re: Pressure Problem (Bitterlich, Mark G CIV NAVAIR, WD)
18. 09:10 PM - Re: Re: Pressure Problem (Jeff Hove)
Message 1
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| Subject: | Re: Pressure Problem |
MOST IMPORTANTLY - If you do this test as Al suggested, be certain to put t
he gear selector back into the UP position BEFORE you put the gear down.-
Putting it back in the UP posistion repressurizes the actuators.- If you
don't do this and put the gear selector DOWN from the neutral position, th
e gear will slam into the down position just like when you extend the gear
with the emergency air system.- It WILL get your attention.=0A=0ADennis
=0A=0A=0A=0A________________________________=0A From: Al Pickering <alpick@
live.com.au>=0ATo: "yak-list@matronics.com" <yak-list@matronics.com> =0ASen
t: Tuesday, June 24, 2014 6:23 PM=0ASubject: Re: Yak-List: Pressure Problem
=0A =0A=0A=0AWhen airborne leave the gear selector in neutral after gear up
. If your pressure rises you know you have and actuator leak in the up mode
.=0A=0ASent from Alspad.=0A=0AOn 24 Jun 2014, at 8:29 am, "A. Dennis Savare
se" <dsavarese0812@bellsouth.net> wrote:=0A=0A=0AWhen was the last time you
removed the snot bottle and flushed it out thoroughly through all three or
ifices (in, out and drain).- Try that first.- I think you'll be quite s
urprised at how gunked up the snot bottle can get.=0A>Dennis=0A> =0A>A. Den
nis Savarese=0A334-285-6263=0A334-546-8182 (mobile) www.yak-52.com Skype -
Yakguy1=0AOn 6/23/2014 2:15 PM, Bill1200 wrote:=0A>=0A>--> Yak-List message
posted by: "Bill1200" <billdykes52@hotmail.com> Yak 52=0ANoticed on recent
flight, pressure would not go above about 2.5. Filled it externally to pop
off around 5 after landing. Checked it a several days later, it had bled d
own to about 4.5, not unusual for this plane. Took it out to the ramp, actu
ated flaps until it decreased to about 3, revved it up and watched pressure
build. Went for flight with starting pressure around 3, never got higher
than that during flight. Used U/S detector in both cockpits, around fitting
s, brakes, etc no leak detected. Stumped, any suggestions welcome, thanks.
Read this topic online here: http://forums.matronics.com/viewtopic.php?p=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
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Message 2
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| Subject: | 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 3
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| Subject: | Re: Pressure Problem |
Yes, they are the same and 100% interchangeable.- If you intend to R&R a
gear or flap selector, (the flap selectors and front gear selector are the
same), be very careful removing the fittings because they are quite scarce.
- You can easily gall the pipe threads trying to remove the old ones if y
ou don't heat them up sufficiently before removing them.=0ADennis=0A=0A=0A
=0A________________________________=0A From: keithmckinley <cetopfed@gmail.
com>=0ATo: yak-list@matronics.com =0ASent: Wednesday, June 25, 2014 8:29 AM
=0ASubject: Yak-List: Re: Pressure Problem=0A =0A=0A--> Yak-List message po
sted by: "keithmckinley" <cetopfed@gmail.com>=0A=0AThe gear and flap select
or valve has a small port that will vent air when the selector is moved fro
m 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. =0AIf you have start
ed playing with the ones in the rear cockpit you may start there.- =0A=0A
Mine was a CJ and I believe the selectors are the same in a Yak=0A=0A------
--=0AKeith McKinley=0A700HS=0AX26 Sebastian, FL=0A=0A=0A=0A=0ARead this top
ic online here:=0A=0Ahttp://forums.matronics.com/viewtopic.php?p=425447#4
=========================0A
======================
Message 4
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| Subject: | Pressure Problem |
Absolutely correct, and I forgot about that! It's also a good trick to know from
the aspect of safety. I flew a YAK-50 out to the west coast one time that
had a major leak in when the gear was lowered. Putting the gear handle in
the middle after putting the gear down allowed pressure to build back up before
landing allowing enough air for brakes etc. Not sure if you would want to
try that same trick in a 52 since the gear locking mechanism is totally different.
However, darn good point Al, and something not many know.
Mark
-----Original Message-----
From: owner-yak-list-server@matronics.com [mailto:owner-yak-list-server@matronics.com] On Behalf Of Al Pickering
Sent: Tuesday, June 24, 2014 7:24 PM
Subject: Re: Yak-List: Pressure Problem
When airborne leave the gear selector in neutral after gear up. If your pressure
rises you know you have and actuator leak in the up mode.
Sent from Alspad.
On 24 Jun 2014, at 8:29 am, "A. Dennis Savarese" <dsavarese0812@bellsouth.net>
wrote:
When was the last time you removed the snot bottle and flushed it out thoroughly
through all three orifices (in, out and drain). Try that first. I
think you'll be quite surprised at how gunked up the snot bottle can get.
Dennis
A. Dennis Savarese
334-285-6263
334-546-8182 (mobile)
www.yak-52.com
Skype - Yakguy1
On 6/23/2014 2:15 PM, Bill1200 wrote:
Yak 52
Noticed on recent flight, pressure would not go above about 2.5.
Filled it externally to pop off around 5 after landing. Checked it a several
days later, it had bled down to about 4.5, not unusual for this plane. Took it
out to the ramp, actuated flaps until it decreased to about 3, revved it up
and watched pressure build. Went for flight with starting pressure around 3,
never got higher than that during flight. Used U/S detector in both cockpits,
around fittings, brakes, etc no leak detected. Stumped, any suggestions welcome,
thanks.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=425342#425342
Message 5
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| Subject: | Re: Pressure Problem |
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
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 |
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:
> 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 7
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| Subject: | Re: Pressure Problem |
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:
>
>> 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
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> ==========
>> 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
>> ==========
>>
>>
>>
>>
> *
>
>
> *
>
>
Message 8
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Does anyone off hand know the dimensions of a CJ from wing trailing edge to
tail and to prop hub.
In my typical putting cart before horse approach to things, I purchased a
CJ but haven't taken possession yet, and now I'm wondering if it'll fit in
my T-Hangar.
Thanks
Ernie
Message 9
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| Subject: | Re: CJ Dimensions |
It's about 33' wide and 30 ' long. Mine is in a standard T-hangar which is u
sually 40' X 40' I think.
Richard Hess
C 404-964-4885
> On Jun 26, 2014, at 2:37, Ernest Martinez <erniel29@gmail.com> wrote:
>
> Does anyone off hand know the dimensions of a CJ from wing trailing edge t
o tail and to prop hub.
>
> In my typical putting cart before horse approach to things, I purchased a C
J but haven't taken possession yet, and now I'm wondering if it'll fit in my
T-Hangar.
>
> Thanks
>
> Ernie
>
>
3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3
D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
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D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
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D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
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D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
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>
Message 10
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| Subject: | Re: CJ Dimensions |
This should help.... especially the armament section.=C2-
http://en.wikipedia.org/wiki/Nanchang_CJ-6
=C2-
General characteristics
* Crew: Two (student & instructor)
* Length: 8.46 m (27 ft 9 in)
* Wingspan : 10.22 m (33 ft 6 in)
* Height: 3.3 m (10 ft 8 in)
* Empty weight : 1,095 kg (2,414 lb)
* Max. takeoff weight : 1,400 kg (3,086 lb)
* Powerplant : 1 =C3=97 Zhouzhou (SMPMC) HS6A (different variants uses
different types) radial engine , 213 kW (285 hp)
Performance
* Never exceed speed : 370 km/h (200 kts, 230 mph)
* Maximum speed : 300 km/h (160 kts, 185 mph) diving speed /h (200 kt)
* Range : 700 km (372 nmi, 425 mi)
* Service ceiling : >6,250+ m (20,500+ ft)
Armament
* 2 x 7.62mm machine guns
* Weapons stations and hardpoints under the wings
* Bombs
* Rocket launchers
----- Original Message -----
From: "Ernest Martinez" <erniel29@gmail.com>
Sent: Wednesday, June 25, 2014 12:37:08 PM
Subject: Yak-List: CJ Dimensions
Does anyone off hand know the dimensions of a CJ from wing trailing edge to
tail and to prop hub.
In my typical putting cart before horse approach to things, I purchased a C
J but haven't taken possession yet, and now I'm wondering if it'll fit in m
y T-Hangar.
Thanks
Ernie
===
Message 11
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| Subject: | Re: Pressure Problem |
Dennis pretty much explained this, but the reason is that if you put the gear handle
in the middle, all pressure is released on BOTH sides of the actuator.
The actuator then is at standard atmospheric.
When the gear is then selected to go DOWN, the piston does not have to push compressed
air out the OTHER side to the vent in the gear handle. Thus there is
no resistance at all when 735 PSI of air is applied to the down side.
Think of it this way.... when you normally select DOWN on the gear handle, you
previously had it in the UP position. When it is UP, there is 735 PSI on the
actuator pushing on the UP side.
When you select DOWN, pressure is applied to the other side, but the air is still
in there on the UP side and has to be vented out of the small hole in the gear
handle itself. This acts like a buffer... as the gear goes down, the speed
it goes down is partially controlled by how fast you can vent the air out of
the UP side of the piston, thus this slows down the gear extension.
If you put the handle in the MIDDLE, all the air is vented out..... UP, DOWN,
all of it... vented.
Now when you select DOWN, there is no air cushion to vent out from the UP side,
and the gear is put down with the full force of the 735 PSI of air on the down
side and it just SLAMS DOWN HARD. Not a good thing.
Not my best explanation, but hope you can understand.
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 12:55 PM
Subject: Re: Yak-List: Re: Pressure Problem
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
Message 12
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| Subject: | Re: Pressure Problem |
Dennis and all,
About the air line fittings for the flap and gear valves:
I recently received a shipment which contained 90 degree, 45 degree, and
straight pipe to flare fittings for this application. We also now carry
the air line splicer fittings (double male).
Doug
On Wed, Jun 25, 2014 at 6:36 AM, A. Dennis Savarese <
dsavarese0812@bellsouth.net> wrote:
> Yes, they are the same and 100% interchangeable. If you intend to R&R a
> gear or flap selector, (the flap selectors and front gear selector are the
> same), be very careful removing the fittings because they are quite
> scarce. You can easily gall the pipe threads trying to remove the old ones
> if you don't heat them up sufficiently before removing them.
> Dennis
>
> ------------------------------
> *From:* keithmckinley <cetopfed@gmail.com>
> *To:* yak-list@matronics.com
> *Sent:* Wednesday, June 25, 2014 8:29 AM
> *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=425avigator?Yak-List"
> "http://forums.matronics.com/"
> target="_blank">http://forums.matronics.cosp;
> -nics.com/contribution"
> target="_blank">http://www.matronics.com/contribut==============
>
>
> <http://forums.matronics.com/viewtopic.php?p=425447#425447>
>
> *
>
>
> *
>
>
Message 13
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| Subject: | Re: Pressure Problem |
Here is one more thing to add. Some CJs come WITH OUT up locks. Normally
when you put the gear handle in the middle which lets pressure off both
sides of the piston in the actuator, the gear is held up by the spring loaded
'up locks' otherwise they would fall down. When you put the gear handle
down, not only do you pressurized the down side of the actuator - you also
unlock the up locks - normally. However as I said some CJ (mine in
particular) came WITHOUT up locks. As a result I need to fly with my gear handle
ALWAY in the up position, otherwise they fall down. If I hear air coming
from the gear handle, while the gear handle it self could leak, more than
likely its one the 3 actuators that might be leaking.
My system is simpler in that the line to the up locks are capped off. If
I lose air pressure (bad leak or compressor shear its pins), my gear simply
falls down thanks to gravity. BUT they don't lock over center down, and
that's when I need to use the emergency air pressure. I simply put the
handle down and open the emergency air valve. Over the 20 years I've own my CJ
this has happen twice. Both times was because of a compressor failure of
kind or another.
Jim "Pappy" Goolsby
In a message dated 6/25/2014 2:35:47 P.M. Eastern Daylight Time,
mark.bitterlich@navy.mil writes:
--> Yak-List message posted by: "Bitterlich, Mark G CIV NAVAIR, WD"
<mark.bitterlich@navy.mil>
Dennis pretty much explained this, but the reason is that if you put the
gear handle in the middle, all pressure is released on BOTH sides of the
actuator. The actuator then is at standard atmospheric.
When the gear is then selected to go DOWN, the piston does not have to
push compressed air out the OTHER side to the vent in the gear handle. Thus
there is no resistance at all when 735 PSI of air is applied to the down
side.
Think of it this way.... when you normally select DOWN on the gear handle,
you previously had it in the UP position. When it is UP, there is 735 PSI
on the actuator pushing on the UP side.
When you select DOWN, pressure is applied to the other side, but the air
is still in there on the UP side and has to be vented out of the small hole
in the gear handle itself. This acts like a buffer... as the gear goes
down, the speed it goes down is partially controlled by how fast you can vent
the air out of the UP side of the piston, thus this slows down the gear
extension.
If you put the handle in the MIDDLE, all the air is vented out..... UP,
DOWN, all of it... vented.
Now when you select DOWN, there is no air cushion to vent out from the UP
side, and the gear is put down with the full force of the 735 PSI of air
on the down side and it just SLAMS DOWN HARD. Not a good thing.
Not my best explanation, but hope you can understand.
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 12:55 PM
Subject: Re: Yak-List: Re: Pressure Problem
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:
<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
Subject: Yak-List: Re: Pressure Problem
--> Yak-List message posted by: "keithmckinley" <cetopfed@gmail.com>
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
Message 14
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| Subject: | Re: Pressure Problem |
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
> <mailto: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 <mailto:mark.bitterlich@navy.mil>> wrote:
>
> NAVAIR, WD" <mark.bitterlich@navy.mil
> <mailto: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>
> [mailto: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 <mailto:yak-list@matronics.com>
> Subject: Yak-List: Re: Pressure Problem
>
> <cetopfed@gmail.com <mailto:cetopfed@gmail.com>>
>
> 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
>
> *
>
>
> *
>
>
> *
Message 15
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|
| Subject: | Re: Pressure Problem |
OUTSTANDING! You're are definitely the answer to everyone's prayers on this!
A. Dennis Savarese
334-285-6263
334-546-8182 (mobile)
www.yak-52.com
Skype - Yakguy1
On 6/25/2014 2:02 PM, doug sapp wrote:
> Dennis and all,
> About the air line fittings for the flap and gear valves:
>
> I recently received a shipment which contained 90 degree, 45 degree,
> and straight pipe to flare fittings for this application. We also now
> carry the air line splicer fittings (double male).
>
> Doug
>
>
> On Wed, Jun 25, 2014 at 6:36 AM, A. Dennis Savarese
> <dsavarese0812@bellsouth.net <mailto:dsavarese0812@bellsouth.net>> wrote:
>
> Yes, they are the same and 100% interchangeable. If you intend to
> R&R a gear or flap selector, (the flap selectors and front gear
> selector are the same), be very careful removing the fittings
> because they are quite scarce. You can easily gall the pipe
> threads trying to remove the old ones if you don't heat them up
> sufficiently before removing them.
> Dennis
>
> ------------------------------------------------------------------------
> *From:* keithmckinley <cetopfed@gmail.com <mailto:cetopfed@gmail.com>>
> *To:* yak-list@matronics.com <mailto:yak-list@matronics.com>
> *Sent:* Wednesday, June 25, 2014 8:29 AM
> *Subject:* Yak-List: Re: Pressure Problem
>
> <cetopfed@gmail.com <mailto:cetopfed@gmail.com>>
>
> 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=425avigator?Yak-List"
> "http://forums.matronics.com/"
> target="_blank">http://forums.matronics.cosp;
> -nics.com/contribution"
> target="_blank">http://www.matronics.com/contribut==============
>
>
> <http://forums.matronics.com/viewtopic.php?p=425447#425447>
>
> *
>
> et="_blank">http://www.matronics.com/Navigator?Yak-List
> tp://forums.matronics.com
> _blank">http://www.matronics.com/contribution
>
> *
>
>
> *
>
>
> *
Message 16
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| Subject: | 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 334-285-6263334-546-8182 (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:
>>
>>> 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
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> ==========
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Message 17
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| Subject: | Re: Pressure Problem |
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
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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Message 18
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| Subject: | 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:
>
> 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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