Request to Aeromot: Landing Gear Adjustment Specifications - 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 07:52:31 -0400
Reply-To:     "Ximango Owners Group (XOG)" <XIMANGO@HOME.EASE.LSOFT.COM>
Sender:       "Ximango Owners Group (XOG)" <XIMANGO@HOME.EASE.LSOFT.COM>
From:         Bruce SCHIMMEL <bruce@SCHIMMEL.COM>
Subject:      request to aeromot: landing gear adjustment specifications
Comments: cc: lcastilho@aeromot.com.br, Karoline
          <karoline.pacheco@aeromot.com.br>
In-Reply-To:  <000001c8d1ff$70e28c20$0100000a@toshibauser>
Mime-Version: 1.0 (Apple Message framework v753.1)
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Content-Transfer-Encoding: 7bit

Sandra,

It's great to hear from you again.

There seems to be a consensus that owners are in need of more 
specific guidance on the correct adjustment of the Ximango's landing 
gear.

I believe that  Luiz Castilho and Karoline Pachero are our points of 
contact, and I've cc'd them a copy of this post.

Bruce



On Jun 19, 2008, at 7:27 AM, Sandra wrote:

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



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=========================================================================
Date:         Fri, 20 Jun 2008 06:03:44 +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: request to aeromot: landing gear adjustment specifications
In-Reply-To:  <33239EB4-11DB-4686-927A-A2D027189926@schimmel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit

Hi Bruce,

Good to hear from you, and thankyou for your trouble in passing on my
Aeromot request- I actually have never contacted Aeromot myself but I
know they read our XOGgings. I'm sure between my request and your email
we will receive a response.

AS John Lawton suggested, I hope that something like a SB is released-
perhaps not all owners are on the XOG.

Cheerio,
Sandra.

-----Original Message-----
From: Ximango Owners Group (XOG) [mailto:XIMANGO@HOME.EASE.LSOFT.COM] On
Behalf Of Bruce SCHIMMEL
Sent: Thursday, 19 June 2008 9:53 PM
To: XIMANGO@HOME.EASE.LSOFT.COM
Subject: request to aeromot: landing gear adjustment specifications


Sandra,

It's great to hear from you again.

There seems to be a consensus that owners are in need of more 
specific guidance on the correct adjustment of the Ximango's landing 
gear.

I believe that  Luiz Castilho and Karoline Pachero are our points of 
contact, and I've cc'd them a copy of this post.

Bruce



On Jun 19, 2008, at 7:27 AM, Sandra wrote:

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