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Flibob
Joined: 25 Jun 2014
Posts: 28
Location: Indiana
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 Posted: Thu May 07, 2020 11:33 am Post subject: Nose gear collapse |
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Nose gear collapse
So last Saturday working on a minor air leak at the nose gear selector. Decided to do it outside in the warm spring sunshine. Ended up having to replace the selector so emailed doug to get a new one and left the old selector out. When I push the airplane back in the hanger as I’ve done hundreds of times same hanger the nose gear slowly collapsed onto the tug.
Why did this happen? My theory is that the open circuit on the gear circuit provided no back pressure for the nose down side. But, I really don’t know. I know it’s over center to lock down. I would like to hear any ideas or theories.
Luckily just minor damage to the cowling and the fiberglass on the tug. But I don’t want to move the airplane again until I figure out why it happened.
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pennington.construction.i
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| Posted: Thu May 07, 2020 12:09 pm Post subject: Nose gear collapse |
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Flibob
I am assuming that when you refer to the nose gear selector you are talking
about the nose gear actuator the extends and contracts the gear with air
pressure.
That actuator will hold the nose gear in the down position two ways.
One is with air pressure on the cylinder.
The second way is the locking balls in the actuator in the down position.
When the actuator is extended fully there are three balls that lock the
gear in the down position. I think it is three if I remember what Doug
taught me.
With no air on the actuator the gear will stay down with the balls in the
locked position. If for some reason the actuator was not fully extended
the balls did not lock, the upper and lower jack stays can collapse in the
absence of air pressure.
This is true of the main gear as well.
This is not true for the flap actuator. There are no balls in the flap
actuator.
The locking balls is what enables you to move the plane with the air off
and no pressure in the system.
I’m not sure if the locking balls would hold the airplane up during a
landing and no air pressure.
Doug would be able tell us that.
If I have mis quoted the system Doug let us know.
Mark Pennington
On Thu, May 7, 2020 at 3:41 PM Flibob <Flibob(at)att.net> wrote:
[quote]
Nose gear collapse
So last Saturday working on a minor air leak at the nose gear selector.
Decided to do it outside in the warm spring sunshine. Ended up having to
replace the selector so emailed doug to get a new one and left the old
selector out. When I push the airplane back in the hanger as I’ve done
hundreds of times same hanger the nose gear slowly collapsed onto the tug
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pennington.construction.i
Guest
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| Posted: Thu May 07, 2020 12:22 pm Post subject: Nose gear collapse |
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Flibob
If you had the actuator out of the plane.
The upper and lower jacks stay being over center would not ensure the nose
gear would not collapse.
Mark Pennington.
On Thu, May 7, 2020 at 3:41 PM Flibob <Flibob(at)att.net> wrote:
[quote]
Nose gear collapse
So last Saturday working on a minor air leak at the nose gear selector.
Decided to do it outside in the warm spring sunshine. Ended up having to
replace the selector so emailed doug to get a new one and left the old
selector out. When I push the airplane back in the hanger as I’ve done
hundreds of times same hanger the nose gear slowly collapsed onto the tug
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dougsappllc(at)gmail.com
Guest
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| Posted: Thu May 07, 2020 1:44 pm Post subject: Nose gear collapse |
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The locking balls will hold the aircraft in a 0 air situation if they are in the locked position.
Mark is correct except there are 5 balls not 3. There is a joke here some where................
Better every day.
Doug
On Thu, May 7, 2020 at 1:14 PM Mark Pennington <pennington.construction.inc.1(at)gmail.com (pennington.construction.inc.1(at)gmail.com)> wrote:
| Quote: | Flibob
I am assuming that when you refer to the nose gear selector you are talking about the nose gear actuator the extends and contracts the gear with air pressure.
That actuator will hold the nose gear in the down position two ways.
One is with air pressure on the cylinder.
The second way is the locking balls in the actuator in the down position. When the actuator is extended fully there are three balls that lock the gear in the down position. I think it is three if I remember what Doug taught me.
With no air on the actuator the gear will stay down with the balls in the locked position. If for some reason the actuator was not fully extended the balls did not lock, the upper and lower jack stays can collapse in the absence of air pressure.
This is true of the main gear as well.
This is not true for the flap actuator. There are no balls in the flap actuator.
The locking balls is what enables you to move the plane with the air off and no pressure in the system.
I’m not sure if the locking balls would hold the airplane up during a landing and no air pressure.
Doug would be able tell us that.
If I have mis quoted the system Doug let us know.
Mark Pennington
On Thu, May 7, 2020 at 3:41 PM Flibob <Flibob(at)att.net (Flibob(at)att.net)> wrote:
| Quote: | --> Yak-List message posted by: "Flibob" <Flibob(at)att.net (Flibob(at)att.net)>
Nose gear collapse
So last Saturday working on a minor air leak at the nose gear selector. Decided to do it outside in the warm spring sunshine. Ended up having to replace the selector so emailed doug to get a new one and left the old selector out. When I push the airplane back in the hanger as I’ve done hundreds of times same hanger the nose gear slowly collapsed onto the tug.
Why did this happen? My theory is that the open circuit on the gear circuit provided no back pressure for the nose down side. But, I really don’t know. I know it’s over center to lock down. I would like to hear any ideas or theories.
Luckily just minor damage to the cowling and the fiberglass on the tug. But I don’t want to move the airplane again until I figure out why it happened.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=496246#496246
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dsavarese0812(at)bellsout
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| Posted: Thu May 07, 2020 1:52 pm Post subject: Nose gear collapse |
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Yep! There is.
"It takes more balls than you think to hold up that airplane!" 
A. Dennis Savarese
334-546-8182 (mobile)
www.yak-52.com
Skype - Yakguy1
On 5/7/2020 5:40 PM, doug sapp wrote:
| Quote: | The locking balls will hold the aircraft in a 0 air situation if they
are in the locked position.
Mark is correct except there are 5 balls not 3. There is a joke here
some where................
Better every day.
Doug
On Thu, May 7, 2020 at 1:14 PM Mark Pennington
<pennington.construction.inc.1(at)gmail.com
<mailto:pennington.construction.inc.1(at)gmail.com>> wrote:
Flibob
I am assuming that when you refer to the nose gear selector you
are talking about the nose gear actuator the extends and contracts
the gear with air pressure.
That actuator will hold the nose gear in the down position two ways.
One is with air pressure on the cylinder.
The second way is the locking balls in the actuator in the down
position. When the actuator is extended fully there are three
balls that lock the gear in the down position. I think it is
three if I remember what Doug taught me.
With no air on the actuator the gear will stay down with the balls
in the locked position. If for some reason the actuator was not
fully extended the balls did not lock, the upper and lower jack
stays can collapse in the absence of air pressure.
This is true of the main gear as well.
This is not true for the flap actuator. There are no balls in the
flap actuator.
The locking balls is what enables you to move the plane with the
air off and no pressure in the system.
I’m not sure if the locking balls would hold the airplane up
during a landing and no air pressure.
Doug would be able tell us that.
If I have mis quoted the system Doug let us know.
Mark Pennington
On Thu, May 7, 2020 at 3:41 PM Flibob <Flibob(at)att.net
<mailto:Flibob(at)att.net>> wrote:
<mailto:Flibob(at)att.net>>
Nose gear collapse
So last Saturday working on a minor air leak at the nose gear
selector. Decided to do it outside in the warm spring
sunshine. Ended up having to replace the selector so emailed
doug to get a new one and left the old selector out. When I
push the airplane back in the hanger as I’ve done hundreds of
times same hanger the nose gear slowly collapsed onto the tug.
Why did this happen? My theory is that the open circuit on the
gear circuit provided no back pressure for the nose down side.
But, I really don’t know. I know it’s over center to lock
down. I would like to hear any ideas or theories.
Luckily just minor damage to the cowling and the fiberglass on
the tug. But I don’t want to move the airplane again until I
figure out why it happened.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=496246#496246
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pennington.construction.i
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| Posted: Thu May 07, 2020 1:56 pm Post subject: Nose gear collapse |
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Doug
Will the balls in the locked position hold the aircraft up during a normal landing with zero air. ?
Mark
On Thu, May 7, 2020 at 5:49 PM doug sapp <dougsappllc(at)gmail.com (dougsappllc(at)gmail.com)> wrote:
| Quote: | The locking balls will hold the aircraft in a 0 air situation if they are in the locked position.
Mark is correct except there are 5 balls not 3. There is a joke here some where................
Better every day.
Doug
On Thu, May 7, 2020 at 1:14 PM Mark Pennington <pennington.construction.inc.1(at)gmail.com (pennington.construction.inc.1(at)gmail.com)> wrote:
| Quote: | Flibob
I am assuming that when you refer to the nose gear selector you are talking about the nose gear actuator the extends and contracts the gear with air pressure.
That actuator will hold the nose gear in the down position two ways.
One is with air pressure on the cylinder.
The second way is the locking balls in the actuator in the down position. When the actuator is extended fully there are three balls that lock the gear in the down position. I think it is three if I remember what Doug taught me.
With no air on the actuator the gear will stay down with the balls in the locked position. If for some reason the actuator was not fully extended the balls did not lock, the upper and lower jack stays can collapse in the absence of air pressure.
This is true of the main gear as well.
This is not true for the flap actuator. There are no balls in the flap actuator.
The locking balls is what enables you to move the plane with the air off and no pressure in the system.
I’m not sure if the locking balls would hold the airplane up during a landing and no air pressure.
Doug would be able tell us that.
If I have mis quoted the system Doug let us know.
Mark Pennington
On Thu, May 7, 2020 at 3:41 PM Flibob <Flibob(at)att.net (Flibob(at)att.net)> wrote:
| Quote: | --> Yak-List message posted by: "Flibob" <Flibob(at)att.net (Flibob(at)att.net)>
Nose gear collapse
So last Saturday working on a minor air leak at the nose gear selector. Decided to do it outside in the warm spring sunshine. Ended up having to replace the selector so emailed doug to get a new one and left the old selector out. When I push the airplane back in the hanger as I’ve done hundreds of times same hanger the nose gear slowly collapsed onto the tug.
Why did this happen? My theory is that the open circuit on the gear circuit provided no back pressure for the nose down side. But, I really don’t know. I know it’s over center to lock down. I would like to hear any ideas or theories.
Luckily just minor damage to the cowling and the fiberglass on the tug. But I don’t want to move the airplane again until I figure out why it happened.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=496246#496246
===========
List" rel="noreferrer" target="_blank">http://www.matronics.com/Navigator?Yak-List
===========
FORUMS -
eferrer" target="_blank">http://forums.matronics.com
===========
WIKI -
errer" target="_blank">http://wiki.matronics.com
===========
b Site -
-Matt Dralle, List Admin.
rel="noreferrer" target="_blank">http://www.matronics.com/contribution
===========
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Flibob
Joined: 25 Jun 2014
Posts: 28
Location: Indiana
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| Posted: Thu May 07, 2020 3:13 pm Post subject: Nose gear collapse |
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So in the case we are talking about it would indicate a defective nose gear actuator. Am I reading this correctly?
Sent from my iPhone
| Quote: | On May 7, 2020, at 5:58 PM, Mark Pennington <pennington.construction.inc.1(at)gmail.com> wrote:
Doug
Will the balls in the locked position hold the aircraft up during a normal landing with zero air. ?
Mark
On Thu, May 7, 2020 at 5:49 PM doug sapp <dougsappllc(at)gmail.com (dougsappllc(at)gmail.com)> wrote:
| Quote: | The locking balls willhold the aircraft in a 0 air situation if they are in the locked position.
Mark is correct except there are 5 balls not 3. There is a joke here some where...............
Better every day.
Doug
On Thu, May 7, 2020 at 1:14 PM Mark Pennington <pennington.construction.inc.1(at)gmail.com (pennington.construction.inc.1(at)gmail.com)> wrote:
| Quote: | Flibob
I am assuming that when you refer to the nose gear selector you are talking about the nose gear actuator the extends and contracts the gear with air pressure.
That actuator will hold the nose gear in the down position two ways.
One is with air pressure on the cylinder.
The second way is the locking balls in the actuator in the down position. When the actuator is extended fully there are three balls that lock the gear in the down position. I think it is three if I remember what Doug taught me.
With no air on the actuator the gear will stay down with the balls in the locked position. If for some reason the actuator was not fully extended the balls did not lock, the upper and lower jack stays can collapse in the absence of air pressure.
This is true of the main gear as well.
This is not true for the flap actuator. There are no balls in the flap actuator.
The locking balls is what enables you to move the plane with the air off and no pressure in the system.
I’m not sure if the locking balls would hold the airplane up during a landing and no air pressure.
Doug would be able tell us that.
If I have mis quoted the system Doug let us know.
Mark Pennington
On Thu, May 7, 2020 at 3:41 PM Flibob <Flibob(at)att.net (Flibob(at)att.net)> wrote:
| Quote: | --> Yak-List message posted by: "Flibob" <Flibob(at)att.net (Flibob(at)att.net)>
Nose gear collapse
So last Saturday working on a minor air leak at the nose gear selector. Decided to do it outside in the warm spring sunshine. Ended up having to replace the selector so emailed doug to get a new one and left the old selector out. When I push the airplane back in the hanger as I’ve done hundreds of times same hanger the nose gear slowly collapsed onto the tug.
Why did this happen? My theory is that the open circuit on the gear circuit provided no back pressure for the nose down side. But, I really don’t know. I know it’s over center to lock down. I would like to hear any ideas or theories.
Luckily just minor damage to the cowling and the fiberglass on the tug. But I don’t want to move the airplane again until I figure out why it happened.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=496246#496246
===========
List" rel="noreferrer" target="_blank">http://www.matronics.com/Navigator?Yak-List
===========
FORUMS -
eferrer" target="_blank">http://forums.matronics.com
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WIKI -
errer" target="_blank">http://wiki.matronics.com
===========
b Site -
-Matt Dralle, List Admin.
rel="noreferrer" target="_blank">http://www.matronics.com/contribution
===========
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pennington.construction.i
Guest
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| Posted: Thu May 07, 2020 3:48 pm Post subject: Nose gear collapse |
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Mr Graves
| Quote: | From reading the original post from Flibob. He was trouble shooting his
air leak and determined the NLG actuator needed to be replaced. He ordered
|
one from Doug and left the old one out of the plane. Leaving the NLG on
the ground with no actuator and only the upper and lower jack stay holding
the nose gear in place.
The upper and lower jack stays when installed correctly and the actuator
fully extended do settle into place over center. But this does not ensure
the front nose gear will not collapse with the upper and lower jack stays
only. If you are moving the airplane while the actuator is out and you hit
a bump or jog the airplane while moving it the upper and lower jack stay
could reverse and allow the nose gear to collapse.
Based on the original post I think the gear collapsed because the actuator
was not installed and the gentlemen moved the airplane. If this is
incorrect Flibob could give us more info.
Based on a guy I know named Doug. He told me anytime your working on the
landing gear. Have the plane on Jacks. The plane could collapse onto the
floor of the hangar and onto the person under it in the right conditions.
The only way the gear can not collapse while on the ground is to have full
pressure on the gear. And the other way is to ensure the 5 balls are
engaged with zero pressure on the landing gear system. To do this, in the
words of another CJ owner "whack the crap out of the incline brace struts
on the main gear and the upper and lower jack stays on the nose gear at
their pivot point using a 4x4".
It should not collapse. Do the "whack test" while on Jacks...
If I am incorrect in any of this please feel free to lend a hand and help
out with more information.
Mark Pennington
<https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=icon>
Virus-free.
www.avast.com
<https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=link>
<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
On Thu, May 7, 2020 at 7:17 PM Robert Graves <flibob(at)att.net> wrote:
[quote] So in the case we are talking about it would indicate a defective nose
gear actuator. Am I reading this correctly?
Sent from my iPhone
On May 7, 2020, at 5:58 PM, Mark Pennington <
pennington.construction.inc.1(at)gmail.com> wrote:
Doug
Will the balls in the locked position hold the aircraft up during a normal
landing with zero air. ?
Mark
On Thu, May 7, 2020 at 5:49 PM doug sapp <dougsappllc(at)gmail.com> wrote:
> The locking balls will hold the aircraft in a 0 air situation if they are
> in the locked position.
> Mark is correct except there are 5 balls not 3. There is a joke here
> some where................
>
> Better every day.
> Doug
>
> On Thu, May 7, 2020 at 1:14 PM Mark Pennington <
> pennington.construction.inc.1(at)gmail.com> wrote:
>
>> Flibob
>>
>> I am assuming that when you refer to the nose gear selector you are
>> talking about the nose gear actuator the extends and contracts the gear
>> with air pressure.
>>
>> That actuator will hold the nose gear in the down position two ways.
>>
>> One is with air pressure on the cylinder.
>>
>> The second way is the locking balls in the actuator in the down
>> position. When the actuator is extended fully there are three balls that
>> lock the gear in the down position. I think it is three if I remember what
>> Doug taught me.
>>
>> With no air on the actuator the gear will stay down with the balls in
>> the locked position. If for some reason the actuator was not fully
>> extended the balls did not lock, the upper and lower jack stays can
>> collapse in the absence of air pressure.
>>
>> This is true of the main gear as well.
>> This is not true for the flap actuator. There are no balls in the flap
>> actuator.
>>
>> The locking balls is what enables you to move the plane with the air off
>> and no pressure in the system.
>>
>> I’m not sure if the locking balls would hold the airplane up during a
>> landing and no air pressure.
>>
>> Doug would be able tell us that.
>>
>> If I have mis quoted the system Doug let us know.
>>
>> Mark Pennington
>>
>>
>>
>>
>>
>>
>>
>> On Thu, May 7, 2020 at 3:41 PM Flibob <Flibob(at)att.net> wrote:
>>
>>>
>>>
>>> Nose gear collapse
>>> So last Saturday working on a minor air leak at the nose gear selector
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pennington.construction.i
Guest
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| Posted: Thu May 07, 2020 3:51 pm Post subject: Nose gear collapse |
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|
Yup. That’s the joke. 👍
On Thu, May 7, 2020 at 5:56 PM A. Dennis Savarese <
dsavarese0812(at)bellsouth.net> wrote:
[quote]
dsavarese0812(at)bellsouth.net>
Yep! There is.
"It takes more balls than you think to hold up that airplane!"
A. Dennis Savarese
334-546-8182 (mobile)
www.yak-52.com
Skype - Yakguy1
On 5/7/2020 5:40 PM, doug sapp wrote:
> The locking balls will hold the aircraft in a 0 air situation if they
> are in the locked position.
> Mark is correct except there are 5 balls not 3. There is a joke here
> some where................
>
> Better every day.
> Doug
>
> On Thu, May 7, 2020 at 1:14 PM Mark Pennington
> <pennington.construction.inc.1(at)gmail.com
> <mailto:pennington.construction.inc.1(at)gmail.com>> wrote:
>
> Flibob
>
> I am assuming that when you refer to the nose gear selector you
> are talking about the nose gear actuator the extends and contracts
> the gear with air pressure.
>
> That actuator will hold the nose gear in the down position two ways
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Flibob
Joined: 25 Jun 2014
Posts: 28
Location: Indiana
|
| Posted: Thu May 07, 2020 5:28 pm Post subject: Nose gear collapse |
|
|
Mark, Thanks for all your help. My original message said I left out the landing gear selector a better terminology would’ve been the valve at the gear handle. The actuator was in the airplane at the time.
Sent from my iPhone
| Quote: | On May 7, 2020, at 7:50 PM, Mark Pennington <pennington.construction.inc.1(at)gmail.com> wrote:
Mr Graves
From reading the original post from Flibob. He was trouble shooting his air leak and determined the NLG actuator needed to be replaced. He ordered one from Doug and left the old one out of the plane. Leaving the NLG on the ground with no actuator and only the upper and lower jack stay holding the nose gear in place.
The upper and lower jack stays when installed correctly and the actuator fully extended do settle into place over center. But this does not ensure the front nose gear will not collapse with the upper and lower jack stays only. If you are moving the airplane while the actuator is out and you hit a bump or jog the airplane while moving it the upper and lower jack stay could reverse and allow the nose gear to collapse.
Based on the original post I think the gear collapsed because the actuator was not installed and the gentlemen moved the airplane. If this is incorrect Flibob could give us more info.
Based on a guy I know named Doug. He told me anytime your working on the landing gear. Have the plane on Jacks. The plane could collapse onto the floor of the hangar and onto the person under it in the right conditions. The only way the gear can not collapse while on the ground is to have full pressure on the gear. And the other way is to ensure the 5 balls are engaged with zero pressure on the landing gear system. To do this, in the words of another CJ owner "whack the crap out of the incline brace struts on the main gear and the upper and lower jack stays on the nose gear at their pivot point using a 4x4".
It should not collapse. Do the "whack test" while on Jacks...
If I am incorrect in any of this please feel free to lend a hand and help out with more information.
Mark Pennington
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On Thu, May 7, 2020 at 7:17 PM Robert Graves <flibob(at)att.net (flibob(at)att.net)> wrote:
| Quote: | So in the case we are talking about it would indicate a defective nose gear actuator. Am I reading this correctly?
Sent from my iPhone
| Quote: | On May 7, 2020, at 5:58 PM, Mark Pennington <pennington.construction.inc.1(at)gmail.com (pennington.construction.inc.1(at)gmail.com)> wrote:
Doug
Will the balls in the locked position hold the aircraft up during a normal landing with zero air. ?
Mark
On Thu, May 7, 2020 at 5:49 PM doug sapp <dougsappllc(at)gmail.com (dougsappllc(at)gmail.com)> wrote:
| Quote: | The locking balls will hold the aircraft in a 0 air situation if they are in the locked position.
Mark is correct except there are 5 balls not 3. There is a joke here some where................
Better every day.
Doug
On Thu, May 7, 2020 at 1:14 PM Mark Pennington <pennington.construction.inc.1(at)gmail.com (pennington.construction.inc.1(at)gmail.com)> wrote:
| Quote: | Flibob
I am assuming that when you refer to the nose gear selector you are talking about the nose gear actuator the extends and contracts the gear with air pressure.
That actuator will hold the nose gear in the down position two ways.
One is with air pressure on the cylinder.
The second way is the locking balls in the actuator in the down position. When the actuator is extended fully there are three balls that lock the gear in the down position. I think it is three if I remember what Doug taught me.
With no air on the actuator the gear will stay down with the balls in the locked position. If for some reason the actuator was not fully extended the balls did not lock, the upper and lower jack stays can collapse in the absence of air pressure.
This is true of the main gear as well.
This is not true for the flap actuator. There are no balls in the flap actuator.
The locking balls is what enables you to move the plane with the air off and no pressure in the system.
I’m not sure if the locking balls would hold the airplane up during a landing and no air pressure.
Doug would be able tell us that.
If I have mis quoted the system Doug let us know.
Mark Pennington
On Thu, May 7, 2020 at 3:41 PM Flibob <Flibob(at)att.net (Flibob(at)att.net)> wrote:
| Quote: | --> Yak-List message posted by: "Flibob" <Flibob(at)att.net (Flibob(at)att.net)>
Nose gear collapse
So last Saturday working on a minor air leak at the nose gear selector. Decided to do it outside in the warm spring sunshine. Ended up having to replace the selector so emailed doug to get a new one and left the old selector out. When I push the airplane back in the hanger as I’ve done hundreds of times same hanger the nose gear slowly collapsed onto the tug.
Why did this happen? My theory is that the open circuit on the gear circuit provided no back pressure for the nose down side. But, I really don’t know. I know it’s over center to lock down. I would like to hear any ideas or theories.
Luckily just minor damage to the cowling and the fiberglass on the tug. But I don’t want to move the airplane again until I figure out why it happened.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=496246#496246
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n13472(at)aol.com
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| Posted: Thu May 07, 2020 7:08 pm Post subject: Nose gear collapse |
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It collapsed because it was not adjusted correctly and / or proper
maintenance was not done.
Tom Elliott
CJ-6A NX63727
777 Quartz Ave
PMB 7004
Sandy Valley NV.
89019
Cell 541-297-5497
N13472(at)AOL.COM
--
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pennington.construction.i
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| Posted: Fri May 08, 2020 12:48 am Post subject: Nose gear collapse |
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Mr Graves. I did not recognize you as Flibob.
It does sound like your nose gear actuator did fail to lock and hold up the plane for some reason.
There is a message in the thread from Tom Elliot.
He offered to share his procedure for testing etc.
He has shared that with me and I use that information to check my landing gear each year at condition inspection. He is a good resource
Mark
On Thu, May 7, 2020 at 9:32 PM Robert Graves <flibob(at)att.net (flibob(at)att.net)> wrote:
| Quote: | Mark, Thanks for all your help. My original message said I left out the landing gear selector a better terminology would’ve been the valve at the gear handle. The actuator was in the airplane at the time.
Sent from my iPhone
| Quote: | On May 7, 2020, at 7:50 PM, Mark Pennington <pennington.construction.inc.1(at)gmail.com (pennington.construction.inc.1(at)gmail.com)> wrote:
Mr Graves
From reading the original post from Flibob. He was trouble shooting his air leak and determined the NLG actuator needed to be replaced. He ordered one from Doug and left the old one out of the plane. Leaving the NLG on the ground with no actuator and only the upper and lower jack stay holding the nose gear in place.
The upper and lower jack stays when installed correctly and the actuator fully extended do settle into place over center. But this does not ensure the front nose gear will not collapse with the upper and lower jack stays only. If you are moving the airplane while the actuator is out and you hit a bump or jog the airplane while moving it the upper and lower jack stay could reverse and allow the nose gear to collapse.
Based on the original post I think the gear collapsed because the actuator was not installed and the gentlemen moved the airplane. If this is incorrect Flibob could give us more info.
Based on a guy I know named Doug. He told me anytime your working on the landing gear. Have the plane on Jacks. The plane could collapse onto the floor of the hangar and onto the person under it in the right conditions. The only way the gear can not collapse while on the ground is to have full pressure on the gear. And the other way is to ensure the 5 balls are engaged with zero pressure on the landing gear system. To do this, in the words of another CJ owner "whack the crap out of the incline brace struts on the main gear and the upper and lower jack stays on the nose gear at their pivot point using a 4x4".
It should not collapse. Do the "whack test" while on Jacks...
If I am incorrect in any of this please feel free to lend a hand and help out with more information.
Mark Pennington
Virus-free. www.avast.com [url=#m_-4859219907387057860_DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2][/url]
On Thu, May 7, 2020 at 7:17 PM Robert Graves <flibob(at)att.net (flibob(at)att.net)> wrote:
| Quote: | So in the case we are talking about it would indicate a defective nose gear actuator. Am I reading this correctly?
Sent from my iPhone
| Quote: | On May 7, 2020, at 5:58 PM, Mark Pennington <pennington.construction.inc.1(at)gmail.com (pennington.construction.inc.1(at)gmail.com)> wrote:
Doug
Will the balls in the locked position hold the aircraft up during a normal landing with zero air. ?
Mark
On Thu, May 7, 2020 at 5:49 PM doug sapp <dougsappllc(at)gmail.com (dougsappllc(at)gmail.com)> wrote:
| Quote: | The locking balls will hold the aircraft in a 0 air situation if they are in the locked position.
Mark is correct except there are 5 balls not 3. There is a joke here some where................
Better every day.
Doug
On Thu, May 7, 2020 at 1:14 PM Mark Pennington <pennington.construction.inc.1(at)gmail.com (pennington.construction.inc.1(at)gmail.com)> wrote:
| Quote: | Flibob
I am assuming that when you refer to the nose gear selector you are talking about the nose gear actuator the extends and contracts the gear with air pressure.
That actuator will hold the nose gear in the down position two ways.
One is with air pressure on the cylinder.
The second way is the locking balls in the actuator in the down position. When the actuator is extended fully there are three balls that lock the gear in the down position. I think it is three if I remember what Doug taught me.
With no air on the actuator the gear will stay down with the balls in the locked position. If for some reason the actuator was not fully extended the balls did not lock, the upper and lower jack stays can collapse in the absence of air pressure.
This is true of the main gear as well.
This is not true for the flap actuator. There are no balls in the flap actuator.
The locking balls is what enables you to move the plane with the air off and no pressure in the system.
I’m not sure if the locking balls would hold the airplane up during a landing and no air pressure.
Doug would be able tell us that.
If I have mis quoted the system Doug let us know.
Mark Pennington
On Thu, May 7, 2020 at 3:41 PM Flibob <Flibob(at)att.net (Flibob(at)att.net)> wrote:
| Quote: | --> Yak-List message posted by: "Flibob" <Flibob(at)att.net (Flibob(at)att.net)>
Nose gear collapse
So last Saturday working on a minor air leak at the nose gear selector. Decided to do it outside in the warm spring sunshine. Ended up having to replace the selector so emailed doug to get a new one and left the old selector out. When I push the airplane back in the hanger as I’ve done hundreds of times same hanger the nose gear slowly collapsed onto the tug.
Why did this happen? My theory is that the open circuit on the gear circuit provided no back pressure for the nose down side. But, I really don’t know. I know it’s over center to lock down. I would like to hear any ideas or theories.
Luckily just minor damage to the cowling and the fiberglass on the tug. But I don’t want to move the airplane again until I figure out why it happened.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=496246#496246
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rel="noreferrer" target="_blank">http://www.matronics.com/contribution
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bwade154(at)yahoo.com
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| Posted: Fri May 08, 2020 4:36 am Post subject: Nose gear collapse |
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There is one other thing that could have happened and that is the original equipment had steel balls and steel in a hi moisture environment will rust and could rust to the point of not being able to lock the piston in place, might want to replace the balls in that actuator with stainless steel, unless it is recorded in the logs somewhere that it has been done. One of the first maintenance items I did on my Yak 52 and it had rusty steel ball's.
On Thursday, May 7, 2020, 11:27:06 PM EDT, Robert Graves <flibob(at)att.net> wrote:
Mark, Thanks for all your help. My original message said I left out the landing gear selector a better terminology would’ve been the valve at the gear handle. The actuator was in the airplane at the time.Sent from my iPhone
| Quote: | On May 7, 2020, at 7:50 PM, Mark Pennington <pennington.construction.inc.1(at)gmail.com> wrote:Mr Graves
From reading the original post from Flibob. He was trouble shooting his air leak and determined the NLG actuator needed to be replaced. He ordered one from Doug and left the old one out of the plane. Leaving the NLG on the ground with no actuator and only the upper and lower jack stay holding the nose gear in place.
The upper and lower jack stays when installed correctly and the actuator fully extended do settle into place over center. But this does not ensure the front nose gear will not collapse with the upper and lower jack stays only. If you are moving the airplane while the actuator is out and you hit a bump or jog the airplane while moving it the upper and lower jack stay could reverse and allow the nose gear to collapse.
Based on the original post I think the gear collapsed because the actuator was not installed and the gentlemen moved the airplane. If this is incorrect Flibob could give us more info.
Based on a guy I know named Doug. He told me anytime your working on the landing gear. Have the plane on Jacks. The plane could collapse onto the floor of the hangar and onto the person under it in the right conditions. The only way the gear can not collapse while on the ground is to have full pressure on the gear. And the other way is to ensure the 5 balls are engaged with zero pressure on the landing gear system. To do this, in the words of another CJ owner "whack the crap out of the incline brace struts on the main gear and the upper and lower jack stays on the nose gear at their pivot point using a 4x4".
It should not collapse. Do the "whack test" while on Jacks...
If I am incorrect in any of this please feel free to lend a hand and help out with more information.
Mark Pennington
Virus-free. www.avast.com [url=#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2][/url]
On Thu, May 7, 2020 at 7:17 PM Robert Graves <flibob(at)att.net (flibob(at)att.net)> wrote:
| Quote: | So in the case we are talking about it would indicate a defective nose gear actuator. Am I reading this correctly?Sent from my iPhone
| Quote: | On May 7, 2020, at 5:58 PM, Mark Pennington <pennington.construction.inc.1(at)gmail.com (pennington.construction.inc.1(at)gmail.com)> wrote:Doug
Will the balls in the locked position hold the aircraft up during a normal landing with zero air. ?
Mark
On Thu, May 7, 2020 at 5:49 PM doug sapp <dougsappllc(at)gmail.com (dougsappllc(at)gmail.com)> wrote:
| Quote: | The locking balls will hold the aircraft in a 0 air situation if they are in the locked position.
Mark is correct except there are 5 balls not 3. There is a joke here some where................
Better every day.
Doug
On Thu, May 7, 2020 at 1:14 PM Mark Pennington <pennington.construction.inc.1(at)gmail.com (pennington.construction.inc.1(at)gmail.com)> wrote:
| Quote: | Flibob
I am assuming that when you refer to the nose gear selector you are talking about the nose gear actuator the extends and contracts the gear with air pressure.
That actuator will hold the nose gear in the down position two ways.
One is with air pressure on the cylinder.
The second way is the locking balls in the actuator in the down position. When the actuator is extended fully there are three balls that lock the gear in the down position. I think it is three if I remember what Doug taught me.
With no air on the actuator the gear will stay down with the balls in the locked position. If for some reason the actuator was not fully extended the balls did not lock, the upper and lower jack stays can collapse in the absence of air pressure.
This is true of the main gear as well.
This is not true for the flap actuator. There are no balls in the flap actuator.
The locking balls is what enables you to move the plane with the air off and no pressure in the system.
I’m not sure if the locking balls would hold the airplane up during a landing and no air pressure.
Doug would be able tell us that.
If I have mis quoted the system Doug let us know.
Mark Pennington
On Thu, May 7, 2020 at 3:41 PM Flibob <Flibob(at)att.net (Flibob(at)att.net)> wrote:
| Quote: | | --> Yak-List message posted by: "Flibob" <Flibob(at)att.net (Flibob(at)att.net)> Nose gear collapse So last Saturday working on a minor air leak at the nose gear selector. Decided to do it outside in the warm spring sunshine. Ended up having to replace the selector so emailed doug to get a new one and left the old selector out. When I push the airplane back in the hanger as I’ve done hundreds of times same hanger the nose gear slowly collapsed onto the tug. Why did this happen? My theory is that the open circuit on the gear circuit provided no back pressure for the nose down side. But, I really don’t know. I know it’s over center to lock down. I would like to hear any ideas or theories. Luckily just minor damage to the cowling and the fiberglass on the tug. But I don’t want to move the airplane again until I figure out why it happened. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=496246#496246 =========== List" rel="noreferrer" target="_blank">http://www.matronics.com/Navigator?Yak-List =========== FORUMS - eferrer" target="_blank">http://forums.matronics.com =========== WIKI - errer" target="_blank">http://wiki.matronics.com =========== b Site - -Matt Dralle, List Admin. rel="noreferrer" target="_blank">http://www.matronics.com/contribution =========== |
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woodja51
Joined: 13 May 2015
Posts: 40
Location: MELBOURNE AUSTRALIA
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| Posted: Wed Aug 05, 2020 8:54 pm Post subject: Re: Nose gear collapse |
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Moving the aircraft without actuators installed will most definitely lead to a collapse. Without the air /and or balls locked in, the same thing might happen depending on which way you move it. For the interest of safety, making up some gear locks when doing anything on the undercarriage unless its on jacks is a good idea. These might simply be two bits of half tube with strong zip ties to ensure the down stay remains over centre. Or a piece of appropriate sized wood inserted to ensure the over centre. even modern airliners ground crew ( in general ) insert the lock pins when towing aircraft - even with hydraulics applied. FWIW. M
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JL2A
Joined: 07 Apr 2015
Posts: 113
Location: Australia
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| Posted: Fri Aug 07, 2020 7:41 pm Post subject: Re: Nose gear collapse |
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Rusty balls or the gear was incorrectly set up - not sure if this has been covered?
Refer the maintenance manual but essentially if the Gear braces / jack stays hit the over centre stop before the actuator is fully extended then the balls will not lock the actuator internally. Without air pressure you’re down to only the over centre to keep the gear from folding up. When pulled with the tug the jack stays would’ve ‘straightened’ and then you’re down to pure luck as the next bump on the tow bar in direction of deceleration could fold them back one of two ways... fortunately for the OP it seems it chose To collapse, better then than with the engine running & taxiing with gear handle in neutral inadvertently...
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