Today's Message Index:
----------------------
1. 05:00 AM - Re: VA-144 Nose Gear Bushing (Gary)
2. 06:45 AM - Re: VA-144 Nose Gear Bushing (Chris)
3. 07:57 AM - Re: SB Nose Wheel Report (David Leikam)
4. 08:04 AM - Re: VA-144 Nose Gear Bushing (Sean Stephens)
5. 08:52 AM - Re: SB Nose Wheel Report (dmaib@me.com)
6. 02:01 PM - Re: Re: SB Nose Wheel Report (speckter@comcast.net)
7. 03:01 PM - Re: SB Nose Wheel Report (Bob Turner)
8. 04:14 PM - Re: Re: SB Nose Wheel Report (Gary)
9. 04:59 PM - Re: Re: SB Nose Wheel Report (Phillip Perry)
Message 1
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| Subject: | Re: VA-144 Nose Gear Bushing |
That was Robin Marks. But I don't remember more about it.
Gary SPECKETER
> On Sep 19, 2014, at 7:38 PM, Sean Stephens <sean@stephensville.com> wrote:
>
>
> I had the nose lifted off the ground to start the recent service bulletin (no
cracks) and noticed another issue.
>
> One of my VA-144 bushings, which is used where the nose gear leg attaches to
the engine mount (plans page 46-5) has a lot of play in it. I can grab the nose
gear leg and make it rock left to right and hear the play in the bushing in
the engine mount. Only ~60 hours on the plane, so I'm sure it has been that
way since the beginning, but just noticed it now.
>
> I recall someone else mentioning that issue and having a fix for it, but I can't
locate the conversation in the search. Can't remember if they had a new bushing
made. Anyone recall the person that posted about this a year or two ago?
>
> Thanks,
>
> -Sean #40303
>
>
>
>
Message 2
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| Subject: | VA-144 Nose Gear Bushing |
I had this problem last inspection. I only had about 70 hours too. I am not
sure if they actually wore or not, they may have gone in tight only because
of paint and then with paint wearing the problem shows up. I think the
engine mount holes are too big from the start though. Anyway, the fix was
the below parts from Van's. They have these oversized bushings ready, but
not really listed online. Once I got these parts I borrowed some pin gauges
from the machine shop to check my engine mount boss diameters precisely. I
picked the gauge that fit in the boss with the best feel not too tight, but
no play. Then I had the machine shop machine the oversized bushings outside
diameter to that pin gauge size (+/-.002). It is nice and smooth action now
with no wobble. The bolts were fine as were the bolt holes in the bushings,
all the play was between the bushing and engine mount boss.
I have not done bulletin yet.
Good Luck
Chris Lucas
N919AR
-----Original Message-----
From: Sterling Langrell [mailto:sterling@vansaircraft.com]
Sent: Tuesday, January 28, 2014 11:06 AM
Subject: Re: RV-10 Nose gear leg?
We do have an oversized bushing available but it will require you modify it
to fit your mount.
In most cases the problem has been between the bushing and the engine mount
and not the bolt and the bushing. You will want to address this and
eliminate the movement.
Sterling
BUSH-ST 313X780X1.563
R0 VA-144 OVSZ
OVERSIZED BUSHING
-----Original Message-----
From: owner-rv10-list-server@matronics.com
[mailto:owner-rv10-list-server@matronics.com] On Behalf Of Sean Stephens
Sent: Friday, September 19, 2014 7:39 PM
Subject: RV10-List: VA-144 Nose Gear Bushing
I had the nose lifted off the ground to start the recent service bulletin
(no cracks) and noticed another issue.
One of my VA-144 bushings, which is used where the nose gear leg attaches to
the engine mount (plans page 46-5) has a lot of play in it.
I can grab the nose gear leg and make it rock left to right and hear the
play in the bushing in the engine mount. Only ~60 hours on the plane, so
I'm sure it has been that way since the beginning, but just noticed it now.
I recall someone else mentioning that issue and having a fix for it, but I
can't locate the conversation in the search. Can't remember if they had a
new bushing made. Anyone recall the person that posted about this a year or
two ago?
Thanks,
-Sean #40303
Message 3
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| Subject: | Re: SB Nose Wheel Report |
I have about 300 hours and found no cracks while completing the SB. #40496, first
flight in March 2011, only landed on grass twice so far.
However, after reading Garys post regarding the hammering affect of the cap on
the top of the plate has anyone considered replacing the spacer washer with a
soft washer to cushion the hammering?
Dave Leikam
On Sep 19, 2014, at 12:41 PM, Bill Watson <Mauledriver@nc.rr.com> wrote:
>
> Yes it is quite true, disassembly is required. The SB correctly requires disassembly
to determine whether there is cracking.
>
> Upon closer inspection I can see a number of hairline cracks radiating out from
the hole. There are 3 main cracks at 90 degrees from each other and a number
of smaller hairline cracks. There is significant deformation of the plate itself.
I have a strong sense that the deformation causes expansion and therefore
tension around the circumference of the hole which leads to the cracking.
As I've said previously, I base out of a relatively rough field that contributed
to a cracked front wheel found during last year's condition inspection.
>
> There is no doubt that the 'crack fix' is much more substantial than the 'doubler-only
fix'. Is it worth the extra cost and effort if not cracks are found?
I doubt it because while the cracks are inevitable if the plate is deformed,
they will not occur at all if the plate remains relatively 'un-deformed' and
flat. Adding the doubler should insure that the plates do not deform and therefore
should not crack.
>
> So my thinking is:
>
> - if I had a flying aircraft with no cracks, adding the doubler will adequately
ensure no deformation in the future. After all, there are many '10s flying
many more hours than mine without any cracking (and presumably little or no deformation)
using the current design.
>
> - If I had a non-flying plane with the engine installed, I'd add the doubler
and fly.
>
> - If I have a non-flying plane with engine in the box, I'd be hard pressed not
to exchange it for the new design, whatever that is.
>
> ...just my very uninformed and qualitative opinion
>
> Bill "both airport owners are welders so I've taken them thru my SB woes looking
for welding help and NOT to foment guilt" Watson
>
> On 9/18/2014 5:31 PM, Werner Schneider wrote:
>>
>> Thanks Bill,
>>
>> interesting, your crack pattern is totally different to the others, without
disassembling you would not find it!
>>
>> And I wonder, it seems the compression under load did crack inside the dynafocal
ring, so the plate will add some stiffness, but the load transfer to the
ring would only be fully covered by welding another ring inside the dynafocal
cup (like in the crack fix).
>>
>> So for "non cracked" the same repair might be the better approach....
>>
>> Time will tell and this will as well request a total disassembly of the nose
gear strut for inspection every then and now to detect your type of failure...
>>
>> Cheers Werner
>>
>> On 13.09.2014 19:54, Bill Watson wrote:
>>
>>> Nose Wheel Mount Status: Cracked at 3rd Condition Inspection. 4 donuts
>>> installed since first flight. There was play in link assembly when
>>> weight is removed from nosewheel
>>>
>>
>>
>>
>>
>>
>>
>> -----
>> No virus found in this message.
>> Checked by AVG - www.avg.com
>>
>>
>
>
>
>
>
Message 4
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| Subject: | Re: VA-144 Nose Gear Bushing |
Thanks for the info Chris. Will get a couple of these ordered.
-Sean
> Chris <mailto:toaster73@embarqmail.com>
> September 20, 2014 at 8:44 AM
>
> I had this problem last inspection. I only had about 70 hours too. I
> am not
> sure if they actually wore or not, they may have gone in tight only
> because
> of paint and then with paint wearing the problem shows up. I think the
> engine mount holes are too big from the start though. Anyway, the fix was
> the below parts from Van's. They have these oversized bushings ready, but
> not really listed online. Once I got these parts I borrowed some pin
> gauges
> from the machine shop to check my engine mount boss diameters precisely. I
> picked the gauge that fit in the boss with the best feel not too
> tight, but
> no play. Then I had the machine shop machine the oversized bushings
> outside
> diameter to that pin gauge size (+/-.002). It is nice and smooth
> action now
> with no wobble. The bolts were fine as were the bolt holes in the
> bushings,
> all the play was between the bushing and engine mount boss.
> I have not done bulletin yet.
> Good Luck
> Chris Lucas
> N919AR
>
> -----Original Message-----
> From: Sterling Langrell [mailto:sterling@vansaircraft.com]
> Sent: Tuesday, January 28, 2014 11:06 AM
> To: Chris
> Subject: Re: RV-10 Nose gear leg?
>
> We do have an oversized bushing available but it will require you
> modify it
> to fit your mount.
> In most cases the problem has been between the bushing and the engine
> mount
> and not the bolt and the bushing. You will want to address this and
> eliminate the movement.
>
> Sterling
>
> BUSH-ST 313X780X1.563
> R0 VA-144 OVSZ
> OVERSIZED BUSHING
>
>
> -----Original Message-----
> From: owner-rv10-list-server@matronics.com
> [mailto:owner-rv10-list-server@matronics.com] On Behalf Of Sean Stephens
> Sent: Friday, September 19, 2014 7:39 PM
> To: rv10-list@matronics.com
> Subject: RV10-List: VA-144 Nose Gear Bushing
>
>
> I had the nose lifted off the ground to start the recent service bulletin
> (no cracks) and noticed another issue.
>
> One of my VA-144 bushings, which is used where the nose gear leg
> attaches to
> the engine mount (plans page 46-5) has a lot of play in it.
> I can grab the nose gear leg and make it rock left to right and hear the
> play in the bushing in the engine mount. Only ~60 hours on the plane, so
> I'm sure it has been that way since the beginning, but just noticed it
> now.
>
> I recall someone else mentioning that issue and having a fix for it, but I
> can't locate the conversation in the search. Can't remember if they had a
> new bushing made. Anyone recall the person that posted about this a
> year or
> two ago?
>
> Thanks,
>
> -Sean #40303
>
>
Message 5
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| Subject: | Re: SB Nose Wheel Report |
arplnplt(at)gmail.com wrote:
> I have about 300 hours and found no cracks while completing the SB. #40496,
first flight in March 2011, only landed on grass twice so far.
> However, after reading Garys post regarding the hammering affect of the cap on
the top of the plate has anyone considered replacing the spacer washer with
a soft washer to cushion the hammering?
>
> Dave Leikam
>
>
>
>
Will there be a hammering effect if the preload is maintained on the rubber elastomers
with the use of the U-1002 isolator washers?
--------
David Maib
RV-10 #40559
New Smyrna Beach, FL
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=430828#430828
Message 6
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| Subject: | Re: SB Nose Wheel Report |
A rubber or similar cushion on the top side of the plate under the hat woul
d not help much.=C2- The force of the hat heading downward from the compr
ession of the elastomers=C2-is cancelled out by the remaining compression
on=C2-elastomers.=C2- However what is not cancelled out is the mass of
the gear,wheel, pant etc accelerating downward.=C2- That is what causes
the hat to hammer the top of the plate which flexes slightly downward and t
hen is flexed back upward by the next compression of the elastomers.=C2-
A classic case of metal fatigue. The thicker plate if adhered properly by e
ither welding or rivets will solve that issue.=C2- That is this builders
analysis.
=C2-
Gary=C2- =C2-
----- Original Message -----
From: dmaib@me.com
Sent: Saturday, September 20, 2014 11:51:56 AM
Subject: RV10-List: Re: SB Nose Wheel Report
arplnplt(at)gmail.com wrote:
> I have about 300 hours and found no cracks while completing the SB. =C2
-#40496, first flight in March 2011, only landed on grass twice so far.
> However, after reading Gary=C3=AF=C2=C2=BDs post regarding the hammeri
ng affect of the cap on the top of the plate has anyone considered replacin
g the spacer washer with a soft washer to cushion the hammering?
>
> Dave Leikam
>
>
> =C2-
>
Will there be a hammering effect if the preload is =C2-maintained on the
rubber elastomers with the use of the U-1002 isolator washers?
--------
David Maib
RV-10 #40559
New Smyrna Beach, FL
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=430828#430828
===========
===========
MS -
===========
e -
=C2- =C2- =C2- =C2- =C2--Matt Dralle, List Admin.
===========
Message 7
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| Subject: | Re: SB Nose Wheel Report |
Gary is correct; on the down stroke the impulse load delivered from the top hat/washer
to the plate is due to the momentum of the nose gear assembly, which has
been accelerated downward due to the compressed donuts.
This is an interesting engineering problem which is very complicated. I've just
started to think about it, but my thoughts are as follows. In the real world,
everything bends (a little). If you hit a bump, the tire flexes, the nose gear
flexes, and if the force applied to the donuts exceeds their static loading
(weight on them, plus preload), they compress and the top hat goes up. Now if
the back side of the bump ends abruptly, the donuts and the slightly flexed nose
gear, plus gravity (pretty negligible here) accelerate the tire downwards.
But in the meantime the tire is somewhat unloaded, and expands to a more-round
shape (especially since it's rotating). If the ground is the same height as before
the bump, the tire hits slightly before the hat; the tire compresses and
then the hat hits. So there is some shock absorption. OTOH if the bump is followed
by a "hole", the wheel is driven downward until the top hat hits. All this
depends on the time constants involved (how fast, how wide is the bump, etc.).
With no calculation at all, my gut feeling is that if the hat was hitting hard
enough to damage the plate, we would also be seeing damage to the AN5 bolt that
ties it to the donut shaft. (They both see the same load).
I do not see the value of gluing the new plate to the old plate, as far as the
downward load imposed by the hat is concerned. In all cases that new plate is
being held up against the mount by hundreds, I think, of pounds of force, from
the compressed donuts; more than RTV could ever hold. The glue may be useful
for keeping the plate from creeping against the other parts of the mount over
time. But frankly I don't see that happening, unless you grease both sides of
the new plate.
I need to think about this some more.
--------
Bob Turner
RV-10 QB
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=430838#430838
Message 8
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| Subject: | Re: SB Nose Wheel Report |
This is a great expansion of my thoughts. Thus my recommendation of riveting or
welding the new plate.
The bolt on the hat is in shear and thus not susceptible to the flexion that affects
the plate. It is the flexion that causes the thin plate to flex and thus
to fail.
Gary
> On Sep 20, 2014, at 6:00 PM, "Bob Turner" <bobturner@alum.rpi.edu> wrote:
>
>
> Gary is correct; on the down stroke the impulse load delivered from the top hat/washer
to the plate is due to the momentum of the nose gear assembly, which
has been accelerated downward due to the compressed donuts.
>
> This is an interesting engineering problem which is very complicated. I've just
started to think about it, but my thoughts are as follows. In the real world,
everything bends (a little). If you hit a bump, the tire flexes, the nose gear
flexes, and if the force applied to the donuts exceeds their static loading
(weight on them, plus preload), they compress and the top hat goes up. Now if
the back side of the bump ends abruptly, the donuts and the slightly flexed
nose gear, plus gravity (pretty negligible here) accelerate the tire downwards.
But in the meantime the tire is somewhat unloaded, and expands to a more-round
shape (especially since it's rotating). If the ground is the same height as
before the bump, the tire hits slightly before the hat; the tire compresses and
then the hat hits. So there is some shock absorption. OTOH if the bump is followed
by a "hole", the wheel is driven downward until the top hat hits. All
this depends on the time constants involved (how fast,!
> how wide is the bump, etc.).
> With no calculation at all, my gut feeling is that if the hat was hitting hard
enough to damage the plate, we would also be seeing damage to the AN5 bolt that
ties it to the donut shaft. (They both see the same load).
>
> I do not see the value of gluing the new plate to the old plate, as far as the
downward load imposed by the hat is concerned. In all cases that new plate is
being held up against the mount by hundreds, I think, of pounds of force, from
the compressed donuts; more than RTV could ever hold. The glue may be useful
for keeping the plate from creeping against the other parts of the mount over
time. But frankly I don't see that happening, unless you grease both sides of
the new plate.
>
> I need to think about this some more.
>
> --------
> Bob Turner
> RV-10 QB
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=430838#430838
>
>
>
>
>
>
>
>
>
>
Message 9
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| Subject: | Re: SB Nose Wheel Report |
Could it be fastened with screws and made more resilient than rivets?
Haven't done the modification yet and I don't have the parts in my hand to know
if it's possible....
Sent from my iPhone
> On Sep 20, 2014, at 6:13 PM, Gary <speckter@comcast.net> wrote:
>
>
> This is a great expansion of my thoughts. Thus my recommendation of riveting
or welding the new plate.
> The bolt on the hat is in shear and thus not susceptible to the flexion that
affects the plate. It is the flexion that causes the thin plate to flex and thus
to fail.
>
> Gary
>
>> On Sep 20, 2014, at 6:00 PM, "Bob Turner" <bobturner@alum.rpi.edu> wrote:
>>
>>
>> Gary is correct; on the down stroke the impulse load delivered from the top
hat/washer to the plate is due to the momentum of the nose gear assembly, which
has been accelerated downward due to the compressed donuts.
>>
>> This is an interesting engineering problem which is very complicated. I've just
started to think about it, but my thoughts are as follows. In the real world,
everything bends (a little). If you hit a bump, the tire flexes, the nose
gear flexes, and if the force applied to the donuts exceeds their static loading
(weight on them, plus preload), they compress and the top hat goes up. Now
if the back side of the bump ends abruptly, the donuts and the slightly flexed
nose gear, plus gravity (pretty negligible here) accelerate the tire downwards.
But in the meantime the tire is somewhat unloaded, and expands to a more-round
shape (especially since it's rotating). If the ground is the same height as
before the bump, the tire hits slightly before the hat; the tire compresses
and then the hat hits. So there is some shock absorption. OTOH if the bump is
followed by a "hole", the wheel is driven downward until the top hat hits. All
this depends on the time constants involved (how fas!
> t,!
>> how wide is the bump, etc.).
>> With no calculation at all, my gut feeling is that if the hat was hitting hard
enough to damage the plate, we would also be seeing damage to the AN5 bolt
that ties it to the donut shaft. (They both see the same load).
>>
>> I do not see the value of gluing the new plate to the old plate, as far as the
downward load imposed by the hat is concerned. In all cases that new plate
is being held up against the mount by hundreds, I think, of pounds of force, from
the compressed donuts; more than RTV could ever hold. The glue may be useful
for keeping the plate from creeping against the other parts of the mount over
time. But frankly I don't see that happening, unless you grease both sides
of the new plate.
>>
>> I need to think about this some more.
>>
>> --------
>> Bob Turner
>> RV-10 QB
>>
>>
>>
>>
>> Read this topic online here:
>>
>> http://forums.matronics.com/viewtopic.php?p=430838#430838
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>
>
>
>
>
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