Further to John Lawton - Jun 2008

Naturally the overcentre adjustment is critical, and knowledgeable
people have commented on the safety and simplicity design on the u/c.
The best design in the world will not work if out of tolerance.

==========================================

Date:         Thu, 19 Jun 2008 21:27:21 +1000
Reply-To:     "Ximango Owners Group (XOG)" <XIMANGO@HOME.EASE.LSOFT.COM>
Sender:       "Ximango Owners Group (XOG)" <XIMANGO@HOME.EASE.LSOFT.COM>
From:         Sandra <shemango@BIGPOND.COM>
Subject:      Further to John Lawton...
In-Reply-To:  <E4219C5C-89BB-4693-820E-78EA1025CC76@schimmel.com>
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Hello Xoggers,

Two important questions:

To quote John Lawton's excellent email:

... (it) uses a simple bolt and a plain locking nut, it is possible
through 
use  and/or vibration that this locking bolt/nut  arrangement could
loosen up, 
throw off the adjustment and lead to a gear  collapse.

*******
Vibration + time can do some interesting things.
Importantly, is this possible with a *** NEW*** unadjusted nyloc nut???

Naturally the overcentre adjustment is critical, and knowledgeable
people have commented on the safety and simplicity design on the u/c.
The best design in the world will not work if out of tolerance.

We need to get Aeromot to pull their finger out and confirm the
overcentre measure/tolerance ASAP. (Sorry Aeromot for being so frank;
your wonderful a/c has tolerated me for hundreds of landings!!!).
PLEEEEEEESE KIND~AEROMOT READERS, RESPOND.

As in all aspects of life,
There but for the Grace of God, go I....


Sandra Shemango.
200-064
VH-ZBN


-----Original Message-----
From: Ximango Owners Group (XOG) [mailto:XIMANGO@HOME.EASE.LSOFT.COM] On
Behalf Of Bruce SCHIMMEL
Sent: Wednesday, 18 June 2008 10:06 PM
To: XIMANGO@HOME.EASE.LSOFT.COM
Subject: Re: gear collapse, over center gap


John,

Thank you so much for that really clear explanation. The proper 
adjustment to the bolt on the gear-locking arm -- that diagonal, two-
piece flat steel -- would seem to be critical.

I understand that if you hold a ruler across it, you get an "over 
center" measurement of 5/16".

I'll measure my "gap" soon, and let everyone know soon. I'll be 
interested to hear about others.

Does Aeromot or XimangoUSA specify an optimal gap?

Related to this gap would be the angle that the wheels tilt inward. 
They look like this: o\  /o .

I just wonder if that angle is also important?

yrs, B



On Jun 18, 2008, at 7:40 AM, John Lawton wrote:

In a message dated 6/18/2008 4:33:12 AM Eastern Daylight Time,
faselh@EMAIL.ARIZONA.EDU writes:

Without
failure of a specific part, the gear cannot collapse if the  gear is 
assembled
correctly.

Greetings all,

Good point, Hermann.

After spending many hours fiddling with the alignment of my gear  
doors, and
quite likely well over 100 gear cycles during that process, the  
landing gear
on the Ximango appears quite robust when compared to other  aircraft 
we've
serviced. In fact, compared to other aircraft we've serviced, the  
Ximango
appears to be very robustly built on all levels.

There is adjustment on the "over center" locking arm mechanism at the 
gear
leg that locks the gear down. I am referencing the diagonal, two 
piece  arm
that is flat steel which goes from the retract yoke to the gear leg  
itself.

  Is it possible that the gear collapses experienced thus far were  
caused by
improperly adjusted locking mechanisms? If you remove the center  
console,
you'll see that there is also another locking mechanism inside on 
the  gear
retract handle, although I believe it is secondary to the locking 
arm  at the gear
leg. Absent something in the retract assembly completely failing, I  
don't see
how the gear could collapse unless it isn't adjusted properly.

Is there an Aeromot Service Bulletin that covers proper adjustment 
of  the
landing gear? Since the adjustment in the locking mechanism at the 
gear leg
uses a simple bolt and a plain locking nut, it is possible through 
use  and/or
vibration that this locking bolt/nut  arrangement could loosen up, 
throw off the
adjustment and lead to a gear  collapse. It is also possible that 
normal wear
on the bolt head of this  adjustment point could throw off the locking
mechanism and lead to a gear  collapse.  The alignment of this 
locking mechanism is
something  that should probably be checked at least at every annual 
condition
inspection,  if not periodically during normal preflight inspection. 
I doubt
the average  A&P would bother checking this unless there are specific 
factory
instructions to do so because the A&P wouldn't know what was right 
and  what
was wrong.

I would imagine that there is a measurement that could be made to insure
that the locking arm "over centers" the correct amount. Perhaps this 
could  be
accomplished by laying a straight edge over the locking arm and 
measuring the
distance from the straight edge to the center of the locking arm? 
This distance
  on mine appears to be about 5/16". My gear legs also tilt inwards 
slightly.
This  is likely because of the adjustment on the locking mechanism.

I don't think Aeromot is treading any new ground here on this gear 
design.
It appears to operate very similar to other retract mechanisms on other
aircraft I've seen.

Regards,

John  Lawton
Whitwell, TN (TN89)
Ximango #135



**************Gas prices getting you down? Search AOL Autos for
fuel-efficient used cars.      (http://autos.aol.com/used?
ncid=aolaut00050000000007)
=========================================================================
Date:         Thu, 19 Jun 2008 07:47:13 EDT
Reply-To:     "Ximango Owners Group (XOG)" <XIMANGO@HOME.EASE.LSOFT.COM>
Sender:       "Ximango Owners Group (XOG)" <XIMANGO@HOME.EASE.LSOFT.COM>
From:         John Lawton <Thrmlseekr@AOL.COM>
Subject:      Re: Further to John Lawton...
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In a message dated 6/19/2008 7:27:43 AM Eastern Daylight Time, 
shemango@BIGPOND.COM writes:

Naturally the overcentre adjustment is critical, and  knowledgeable
people have commented on the safety and simplicity design on  the u/c.
The best design in the world will not work if out of  tolerance.
 
Hello Sandra,
 
There are some other things that could happen to throw the over center 
adjustment out of kilter, primarily, wear on the bolt head or on the  corresponding
pad that has been riveted to the lower articulated strut where it  meets the
bolt head when the gear is down. I would imagine that the pad that has  been
added to the lower articulated strut is made of a hardened steel, probably 
much harder steel than the strut itself. This was likely done because the 
adjustment bolt is also hardened. If they'd not done this, the mating  portion on
the lower articulated strut would probably wear away quickly, throw  the
adjustment out and lead to a gear collapse. They both probably still wear  with time,
but much more slowly.
 
Bruce, I think measuring the over-center dimension I measured and measuring 
the angle of the gear leg itself essentially do the same thing. It appears to
me  that the adjustment of this bolt on the upper/lower articulated strut 
arrangement determines the angle of the gear leg itself relative to  plumb.
 
Chuck, is it possible to get some clarification from Aeromot regarding the 
proper adjustment and alignment of the upper and lower articulated struts? 
Perhaps Engineer Castilho at Aeromot could help?

Regards,
 
John  Lawton
Whitwell, TN (TN89)
Ximango #135



**************Gas prices getting you down? Search AOL Autos for
fuel-efficient used cars.      (http://autos.aol.com/used?ncid=aolaut00050000000007)
=========================================================================
Date:         Thu, 19 Jun 2008 14:20:02 -0400
Reply-To:     "Ximango Owners Group (XOG)" <XIMANGO@HOME.EASE.LSOFT.COM>
Sender:       "Ximango Owners Group (XOG)" <XIMANGO@HOME.EASE.LSOFT.COM>
From:         Chuck cheeseman <ximangousa@AOL.COM>
Subject:      Re: Further to John Lawton...
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John et al,
I am in Chicago on my pdf, so will be brief till I get back Sunday.  The way=
 we use the MM instructions is to adjist the bolt to align the two gear 'rod=
s' to be at zero degrees to each other,ie parallel.  Then, the bolt is screw=
ed in 2.5 turns, to create the OVER-center geometry lock.  I agree a gap or=20=
an angle would  be a useful  way to check this without needing jacks.  Luiz,=
 is my explanation ok and can you provide a gap or angle that sults from cor=
rect aligment?
Chuck

-----Original Message-----
From: John Lawton <Thrmlseekr@AOL.COM>
Sent: Thursday, June 19, 2008 7:47 AM
To: XIMANGO@HOME.EASE.LSOFT.COM
Subject: Re: Further to John Lawton...

In a message dated 6/19/2008 7:27:43 AM Eastern Daylight Time, =20
shemango@BIGPOND.COM writes:

Naturally the overcentre adjustment is critical, and  knowledgeable
people have commented on the safety and simplicity design on  the u/c.
The best design in the world will not work if out of  tolerance.
=20
Hello Sandra,
=20
There are some other things that could happen to throw the over center =20
adjustment out of kilter, primarily, wear on the bolt head or on the  corres=
ponding=20
pad that has been riveted to the lower articulated strut where it  meets the=
=20
bolt head when the gear is down. I would imagine that the pad that has  been=
=20
added to the lower articulated strut is made of a hardened steel, probably =20
much harder steel than the strut itself. This was likely done because the =20
adjustment bolt is also hardened. If they'd not done this, the mating  porti=
on on=20
the lower articulated strut would probably wear away quickly, throw  the=20
adjustment out and lead to a gear collapse. They both probably still wear  w=
ith time,=20
but much more slowly.
=20
Bruce, I think measuring the over-center dimension I measured and measuring=20=
=20
the angle of the gear leg itself essentially do the same thing. It appears t=
o=20
me  that the adjustment of this bolt on the upper/lower articulated strut =20
arrangement determines the angle of the gear leg itself relative to  plumb.
=20
Chuck, is it possible to get some clarification from Aeromot regarding the =20
proper adjustment and alignment of the upper and lower articulated struts? =20
Perhaps Engineer Castilho at Aeromot could help?

Regards,
=20
John  Lawton
Whitwell, TN (TN89)
Ximango #135



**************Gas prices getting you down? Search AOL Autos for=20
fuel-efficient used cars.      (http://autos.aol.com/used?ncid=3Daolaut00050=
000000007)
=========================================================================
Date:         Fri, 20 Jun 2008 06:13:23 +1000
Reply-To:     "Ximango Owners Group (XOG)" <XIMANGO@HOME.EASE.LSOFT.COM>
Sender:       "Ximango Owners Group (XOG)" <XIMANGO@HOME.EASE.LSOFT.COM>
From:         Sandra <shemango@BIGPOND.COM>
Subject:      Re: Further to John Lawton...
In-Reply-To:  <cc9.30ca0e6a.358ba141@aol.com>
MIME-Version: 1.0
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Thankyou John, for your interesting thoughts.

Re wear on the hardened pad, mine has done a lot of landings and doesn't
seem to have worn, nor any unwanted movement from the wear noticeable
whilst up on jacks. At the next opportunity, I'll put it up on jacks &
specifically check all this.

Regards,
Sandra

-----Original Message-----
From: Ximango Owners Group (XOG) [mailto:XIMANGO@HOME.EASE.LSOFT.COM] On
Behalf Of John Lawton
Sent: Thursday, 19 June 2008 9:47 PM
To: XIMANGO@HOME.EASE.LSOFT.COM
Subject: Re: Further to John Lawton...


In a message dated 6/19/2008 7:27:43 AM Eastern Daylight Time, 
shemango@BIGPOND.COM writes:

Naturally the overcentre adjustment is critical, and  knowledgeable
people have commented on the safety and simplicity design on  the u/c.
The best design in the world will not work if out of  tolerance.
 
Hello Sandra,
 
There are some other things that could happen to throw the over center 
adjustment out of kilter, primarily, wear on the bolt head or on the
corresponding
pad that has been riveted to the lower articulated strut where it  meets
the
bolt head when the gear is down. I would imagine that the pad that has
been
added to the lower articulated strut is made of a hardened steel,
probably 
much harder steel than the strut itself. This was likely done because
the 
adjustment bolt is also hardened. If they'd not done this, the mating
portion on
the lower articulated strut would probably wear away quickly, throw  the

adjustment out and lead to a gear collapse. They both probably still
wear  with time,
but much more slowly.
 
Bruce, I think measuring the over-center dimension I measured and
measuring 
the angle of the gear leg itself essentially do the same thing. It
appears to
me  that the adjustment of this bolt on the upper/lower articulated
strut 
arrangement determines the angle of the gear leg itself relative to
plumb.
 
Chuck, is it possible to get some clarification from Aeromot regarding
the 
proper adjustment and alignment of the upper and lower articulated
struts? 
Perhaps Engineer Castilho at Aeromot could help?

Regards,
 
John  Lawton
Whitwell, TN (TN89)
Ximango #135



**************Gas prices getting you down? Search AOL Autos for
fuel-efficient used cars.
(http://autos.aol.com/used?ncid=aolaut00050000000007)
=========================================================================
Date:         Thu, 19 Jun 2008 18:35:49 EDT
Reply-To:     "Ximango Owners Group (XOG)" <XIMANGO@HOME.EASE.LSOFT.COM>
Sender:       "Ximango Owners Group (XOG)" <XIMANGO@HOME.EASE.LSOFT.COM>
From:         John Lawton <Thrmlseekr@AOL.COM>
Subject:      Re: Further to John Lawton...
MIME-Version: 1.0
Content-Type: text/plain; charset="US-ASCII"
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In a message dated 6/19/2008 2:20:33 PM Eastern Daylight Time, 
ximangousa@AOL.COM writes:

The way  we use the MM instructions is to adjist the bolt to align the two
gear 'rods'  to be at zero degrees to each other,ie parallel.  Then, the bolt is
 screwed in 2.5 turns, to create the OVER-center geometry  lock.


 
 
Hi Chuck,
 
Okay, that makes perfect sense now. I thought that over centering the  upper
and lower articulated struts was how the gear locked down. Probably  something
everyone should check.
 
Thanks!
 
Regards,
 
 
John  Lawton
Whitwell, TN (TN89)
Ximango #135