Matronics Email Lists Forum Index Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
 
 Get Email Distribution Too!Get Email Distribution Too!    FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Nose leg - NANCHANG - Shimmy issue

 
Post new topic   Reply to topic    Matronics Email Lists Forum Index -> Yak-List
View previous topic :: View next topic  
Author Message
woodja51



Joined: 13 May 2015
Posts: 30
Location: MELBOURNE AUSTRALIA

PostPosted: Wed May 01, 2019 10:25 pm    Post subject: Nose leg - NANCHANG - Shimmy issue Reply with quote

Hi all ... have just installed a completely new nose leg ( from China ) on my Chang
. I have been having issues with nose wheel shimmy and figured changing the entire leg / shimmy damper might solve the problem. Tyre is new ( didn’t help original shimmy ) bearings appear to be ok - no slack etc. all greased up etc but when taxi testing it seemed to pull to the right .
Adjustment of the shimmy damper to pull it left seemed to help but I can’t find any sort of centring cam adjustment etc for tracking ?
Is there any ?

The issue is that on a hi speed taxi when lifting the nose then putting it down again after rejecting the takeoff at around 60>knots , it shudders ( shimmy?) quite badly - as if it’s still offset slightly , maybe almost skipping ? Any gurus out there able to enlighten me ? Matt Combat Flights Melbourne +61420347885 mwuillemin(at)mac.com


- The Matronics Yak-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Yak-List
Back to top
View user's profile Send private message
dabear



Joined: 21 Jan 2011
Posts: 92
Location: Warrenton, VA

PostPosted: Thu May 02, 2019 4:45 am    Post subject: Nose leg - NANCHANG - Shimmy issue Reply with quote

Check both tire pressure and strut pressure. If either are at max,
reduce a little.

Bear

On 5/2/2019 2:25 AM, woodja51 wrote:
Quote:


Hi all ... have just installed a completely new nose leg ( from China ) on my Chang
. I have been having issues with nose wheel shimmy and figured changing the entire leg / shimmy damper might solve the problem. Tyre is new ( didn’t help original shimmy ) bearings appear to be ok - no slack etc. all greased up etc but when taxi testing it seemed to pull to the right .
Adjustment of the shimmy damper to pull it left seemed to help but I can’t find any sort of centring cam adjustment etc for tracking ?
Is there any ?

The issue is that on a hi speed taxi when lifting the nose then putting it down again after rejecting the takeoff at around 60>knots , it shudders ( shimmy?) quite badly - as if it’s still offset slightly , maybe almost skipping ? Any gurus out there able to enlighten me ? Matt Combat Flights Melbourne +61420347885 mwuillemin(at)mac.com


Read this topic online here:

http://forums.matronics.com/viewtopic.php?p=489048#489048



- The Matronics Yak-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Yak-List
Back to top
View user's profile Send private message
pennington.construction.i
Guest





PostPosted: Thu May 02, 2019 4:56 am    Post subject: Nose leg - NANCHANG - Shimmy issue Reply with quote

Also jack up the front of the plane so the tire is off of the ground. Use
a tow bar and rotate the nose gear left and right not to exceed 50 deg in
either direction.

You can disconnect the shimmy damper and rotate the nose gear to see if the
centering cam is operating properly.

Look for smooth travel back to center. With the damper. Much quicker with
no damper.

The travel should be the same in either direction.
Mark
N621CJ

On Thu, May 2, 2019 at 8:51 AM dabear(at)damned.org <dabear(at)damned.org> wrote:

[quote]

Check both tire pressure and strut pressure. If either are at max,
reduce a little.

Bear

On 5/2/2019 2:25 AM, woodja51 wrote:
>
>
> Hi all ... have just installed a completely new nose leg ( from China )
on my Chang
> . I have been having issues with nose wheel shimmy and figured changing
the entire leg / shimmy damper might solve the problem. Tyre is new (
didn’t help original shimmy ) bearings appear to be ok - no slack etc.
all greased up etc but when taxi testing it seemed to pull to the right


- The Matronics Yak-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Yak-List
Back to top
dsavarese0812(at)bellsout
Guest





PostPosted: Thu May 02, 2019 7:21 am    Post subject: Nose leg - NANCHANG - Shimmy issue Reply with quote

Have you balanced the front wheel assembly off the airplane?
Have you checked the main gear strut pressures and tire pressures to make certain they are the same on both left and right sides?
Don't discount the possibility of the main gear contributing to the tracking problem. For example, if the airplane is tracking to the right, the left main may be toed in and the right main may be towed out.
Dennis


On Thursday, May 2, 2019, 8:47:57 AM EDT, dabear(at)damned.org <dabear(at)damned.org> wrote:




--> Yak-List message posted by: "dabear(at)damned.org (dabear(at)damned.org)" <dabear(at)damned.org (dabear(at)damned.org)>

Check both tire pressure and strut pressure. If either are at max,

reduce a little.

Bear

On 5/2/2019 2:25 AM, woodja51 wrote:

Quote:
--> Yak-List message posted by: "woodja51" <mwuillemin(at)mac.com (mwuillemin(at)mac.com)>

Quote:


Quote:
Hi all ... have just installed a completely new nose leg ( from China ) on my Chang

Quote:
. I have been having issues with nose wheel shimmy and figured changing the entire leg / shimmy damper might solve the problem. Tyre is new ( didn’t help original shimmy ) bearings appear to be ok - no slack etc. all greased up etc but when taxi testing it seemed to pull to the right .

Quote:
Adjustment of the shimmy damper to pull it left seemed to help but I can’t find any sort of centring cam adjustment etc for tracking ?

Quote:
Is there any ?

Quote:


Quote:
The issue is that on a hi speed taxi when lifting the nose then putting it down again after rejecting the takeoff at around 60>knots , it shudders ( shimmy?) quite badly - as if it’s still offset slightly , maybe almost skipping ? Any gurus out there able to enlighten me ? Matt Combat Flights Melbourne +61420347885 mwuillemin(at)mac.com (mwuillemin(at)mac.com)

Quote:


Quote:


Quote:


Quote:


Quote:
Read this topic online here:

Quote:


Quote:
http://forums.matronics.com/viewtopic.php?p=489048#489048

Quote:


Quote:


Quote:


Quote:


Quote:


Quote:


Quote:


Quote:


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

http://forums.matronics.comhttp://wiki.matronics.com

http://ww======


- The Matronics Yak-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Yak-List
Back to top
pennington.construction.i
Guest





PostPosted: Thu May 02, 2019 7:36 am    Post subject: Nose leg - NANCHANG - Shimmy issue Reply with quote

Good point Dennis

My plane was duck walking at low taxi speeds and breaking on turns.

Both struts were below the 700 psi suggested. And they were in even.

Proper pressure solved all of the issues.

Hope this helps.
Mark

On Thu, May 2, 2019 at 11:27 AM A. Dennis Savarese <
dsavarese0812(at)bellsouth.net> wrote:

[quote] Have you balanced the front wheel assembly off the airplane?
Have you checked the main gear strut pressures and tire pressures to make
certain they are the same on both left and right sides?
Don't discount the possibility of the main gear contributing to the
tracking problem. For example, if the airplane is tracking to the right,
the left main may be toed in and the right main may be towed out.
Dennis

On Thursday, May 2, 2019, 8:47:57 AM EDT, dabear(at)damned.org <
dabear(at)damned.org> wrote:


Check both tire pressure and strut pressure. If either are at max,
reduce a little.

Bear

On 5/2/2019 2:25 AM, woodja51 wrote:
>
>
> Hi all ... have just installed a completely new nose leg ( from China )
on my Chang
> . I have been having issues with nose wheel shimmy and figured changing
the entire leg / shimmy damper might solve the problem. Tyre is new (
didn’t help original shimmy ) bearings appear to be ok - no slack etc.
all greased up etc but when taxi testing it seemed to pull to the right


- The Matronics Yak-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Yak-List
Back to top
wlannon(at)shaw.ca
Guest





PostPosted: Thu May 02, 2019 10:17 am    Post subject: Nose leg - NANCHANG - Shimmy issue Reply with quote

To answer your question, yes there is a centering device. It is the
internal centering cam referred to earlier by Mark. It is not adjustable
and I would hesitate in making any adjustment to the shimmy damper that may
transfer the very high centering load without fully assessing the possible
structural effects.

I have found that both the Chinese nose wheel tire and tube are grossly out
of balance. The wheel on the other hand is reasonably balanced and small
enough to be of little concern unless affected by previous balance attempts.
The tire is marked with a reference point which (in Western use) would be
positioned at the tube stem.

Years ago I built a simple balancing stand for this purpose and purchased a
bunch of truck tire balance patches (presume they still exist but don't
know) and balance the combined tire/tube combination on original (or spare)
wheel using the reference mark as above. Correction patch glued into tire
and assembly mounted per above reference. Final result one hell of a lot of
work but NO shimmy.

Perhaps you could find a tire shop able and willing to do the same.

--


- The Matronics Yak-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Yak-List
Back to top
stephen.hayne



Joined: 01 Nov 2013
Posts: 51
Location: United States

PostPosted: Tue May 14, 2019 9:49 am    Post subject: Re: Nose leg - NANCHANG - Shimmy issue Reply with quote

I completely agree with Walt (out of balance tires), and have been pursuing shimmy for over a year. I still get a little "bzzzttt" when touchdown at ~70knots, so I keep the nose off until 60'ish.

I've statically balanced (no joy), dynamically balanced at a motorcycle shop (much better), rebuilt the shimmy dampener complete with dunking under 5606 to remove all bubbles, rebushed torque links, rebushed strut with new seals, checked all pressures on all struts (went to max pressure on main struts to stop duckwalk when carrying, ummm, heavier instructors) and tires, dynamically balanced mains and set toe, new bearings and races. Whew. Everything feels incredibly solid. But...

So, still hunting. Here's a few pics - the one with the cordless drill is a joke pic! Used a Bridgeport knee mill and CNC lathe for all work.

https://drive.google.com/drive/folders/1XZZezfVFTB5tDHF4xm8E7kHwu-jMVE5e?usp=sharing

Stephen


- The Matronics Yak-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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

_________________
-
Stephen Hayne, Professor, CIS, Colorado State University
666CJA
http://selfsynchronize.com/hayne/plane/cj6.asp
Back to top
View user's profile Send private message Visit poster's website AIM Address
Dawg



Joined: 19 May 2013
Posts: 353

PostPosted: Fri May 17, 2019 12:01 am    Post subject: Nose leg - NANCHANG - Shimmy issue Reply with quote

Preload the bearings a little bit…..
Quote:
On May 15, 2019, at 02:49, stephen.hayne <stephen.hayne(at)gmail.com> wrote:



I completely agree with Walt (out of balance tires), and have been pursuing shimmy for over a year. I still get a little "bzzzttt" when touchdown at ~70knots, so I keep the nose off until 60'ish.

I've statically balanced (no joy), dynamically balanced at a motorcycle shop (much better), rebuilt the shimmy dampener complete with dunking under 5606 to remove all bubbles, rebushed torque links, rebushed strut with new seals, checked all pressures on all struts (went to max pressure on main struts to stop duckwalk when carrying, ummm, heavier instructors) and tires, dynamically balanced mains and set toe, new bearings and races. Whew. Everything feels incredibly solid. But...

So, still hunting. Here's a few pics - the one with the cordless drill is a joke pic! Used a Bridgeport knee mill and CNC lathe for all work.

https://drive.google.com/drive/folders/1XZZezfVFTB5tDHF4xm8E7kHwu-jMVE5e?usp=sharing

Stephen

--------
-
Dr. Stephen C. Hayne, Professor, CIS, Colorado State University
666CJA
http://selfsynchronize.com/hayne/plane/cj6.asp




Read this topic online here:

http://forums.matronics.com/viewtopic.php?p=489224#489224











- The Matronics Yak-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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

_________________
Dawg
Back to top
View user's profile Send private message
Clouddog



Joined: 02 Jun 2016
Posts: 80
Location: Lebanon, TN

PostPosted: Fri May 17, 2019 2:22 pm    Post subject: Nose leg - NANCHANG - Shimmy issue Reply with quote

I had issues of my aircraft pulling to right during taxi for 5 years. Changled tires, pressures etc. Never could get it right. Changed complete nose leg and my issues disappeared. With that said,  I  had also replaced the upper brass bushings that are in the frame of the aircraft where the upper fork of the gear attach prior to installing the new gear and even then, it still pulled to right. My new gear fixed the right pull.

On Thu, May 2, 2019, 01:39 woodja51 <mwuillemin(at)mac.com (mwuillemin(at)mac.com)> wrote:

Quote:
--> Yak-List message posted by: "woodja51" <mwuillemin(at)mac.com>

Hi all ... have just installed a completely new nose leg ( from China ) on my Chang
. I have been having issues with nose wheel shimmy and figured changing the entire leg / shimmy damper might solve the problem. Tyre is new ( didn’t help original shimmy ) bearings appear to be ok - no slack etc. all greased up etc  but when taxi testing it seemed to pull to the right .
Adjustment of the shimmy damper  to pull it left seemed to help but I can’t find any sort of centring cam adjustment etc for tracking ?
 Is there any ?

The issue is that on a hi speed taxi when lifting the nose then putting it down again after rejecting the takeoff at around 60>knots , it shudders ( shimmy?) quite badly - as if it’s still offset slightly , maybe almost skipping ?  Any gurus out there able to enlighten me ? Matt Combat Flights Melbourne +61420347885 mwuillemin(at)mac.com




Read this topic online here:

http://forums.matronics.com/viewtopic.php?p=489048#489048






===========
ics.com/Navigator?Yak-List
===========
FORUMS -
ronics.com
===========
WIKI -
nics.com
===========
b Site -
          -Matt Dralle, List Admin.
ics.com/contribution
===========





- The Matronics Yak-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Yak-List
Back to top
View user's profile Send private message Send e-mail
Display posts from previous:   
Post new topic   Reply to topic    Matronics Email Lists Forum Index -> Yak-List All times are GMT - 8 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


Powered by phpBB © 2001, 2005 phpBB Group