Posted for "Bill Wade"
<super_chipmunk@roadrunner.com>:
I agree. I’m using Carbinges on my IV-P MG doors and I thought they had too
much play. I
think the stock pins are suitable when you’re attaching cowlings
or other curved surfaces but I wanted a tighter fit for use as a hinge,
especially if they’d be used for trim tabs.
I found a source for precision ground VAR stainless
http://www.smallparts.com/stainless-precision-ground-straightened-vacuum-arc/dp/B003R50276/ref=sr_1_1?sr=1-1&qid=1322133332&filterBy.material_browse=16414
. I tried a range of diameters and found 0.083 was a good fit. –Bill Wade
From: Chris Zavatson
Sent: Wednesday, November
23, 2011 10:05 PM
To: lml@lancaironline.net
Subject: [Norton AntiSpam][LML] Re: Legacy vibrations resolved
The
elevator trim tab is perhaps the most neglected control surface that can
really ruin your day. The goal for us should be to remove all
play from the
trim tab system. There are many ADs and service bulletins written against
certified planes specifying the acceptable
limits. We don't have the luxury
of such a guidance and thus only find the limits through experiences conveyed
by others that have
stumbled across the edge. Unfortunately the inherent play
in Carbinge is similar to that of stock MS hinge material and will not
improve
the situation described in Steve's post.
I think Randy's post is also referring to the spherical bearings used in the
tail of the 320/360 MkII and the Legacy in addition to the trim tab hinge
(Randy, correct me if I am wrong). The spherical bearing
can be upgraded to
some made to tighter tolerances and with better alloys.
Chris
Zavatson
N91CZ
360std
www.N91CZ.net
From: John Barrett <jbarrett@carbinge.com>
To:
lml@lancaironline.net
Sent: Tuesday, November 22, 2011 4:53 AM
Subject: [LML] Re: Legacy vibrations
resolved
CARBINGE
FWIW it’s worth a lot.
www.carbinge.com
From:
Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of randy
snarr
Sent: Monday, November 21, 2011 5:29 AM
To:
lml@lancaironline.net
Subject: [LML] Re: Legacy vibrations resolved
Steve,
As a side note, I had a legacy driver
stop by my hangar a few years ago. When
he shut down, there was a definite metal on metal rattle in the tail as the
blades came to a stop. I
started inspecting the back of his plane before he
got out. He had the same play in the hinges. Especially the outer hinge pilot
side.
With the airplane idling, the hinges rattled pretty bad but with the engine
running you could not hear it but it was defintely
there at shut down. The
tell tale gray trails were there as well.
FWIW..
Randy.
"Flight by machines
heavier than air is unpractical and insignificant, if not
utterly impossible"
-Simon Newcomb, 1902
From: Steve Colwell
<mcmess1919@yahoo.com>
To: lml@lancaironline.net
Sent: Sunday, November 20, 2011 7:48 AM
Subject: [LML] Legacy
vibrations resolved
Our Legacy has had a pitch vibration in the stick that comes and goes. It
seems to be related to about 50%
fuel load or less and reduced but stable
power. The plane has about 275 hours and this has been going on since the
first 40
hours. When it is vibrating in level flight (approximately 2 cycles
per second and the stick is visibly moving in a pronounced shake)
it will
continue to vibrate when pitched up at about 1.5 G. After the pitch up, when
pitched down to less than 1 G, the vibration
will quit. After working thru
many of the same contact points firewall forward and the gear doors Paul
Miller had, I still had the
vibration. All the while, I'm thinking, this is a
great way to initiate flutter. I might add, I very carefully rebalanced the
control surfaces after painting.
I mentioned the problem to Chris Zavatson at the Lancair Breakfast Fly-In at
Willows,
CA.. Chris asked if I had checked the control and trim hinges for
play. That was easy, I check them every
pre-flight. Only not the way Chris
checks them. He pushes and pulls looking at the hinge. See video
http://www.n91cz.com/HingePlay/hinges.htm
I replaced the Pitch Trim Hinge Pin with Stainless Steel (3/32” - .09375)
welding wire. Now, no play can be seen in the push pull test. We have put
20+ hours on with the new SS hinge pin and no
more stick shake. I included
Paul’s post of problem areas (see below) since I had some of them
too.
Steve Colwell Legacy RG 310 hours
Sent: Monday, April 12, 2010 6:47
AM
To: lml@lancaironline.net
Subject: [LML] Legacy vibrations resolved
I had written about vibrations in the 300
hour Legacy engine
compartment. Many wrote about their fixes. I am happy to report that
the following
worked for me:
1) Changed engine isolators last year (no difference)
2) enlarged cutout on nose gear door
stiffener. After repeatedly seeing new
witness marks I did a retraction test and saw the interference is much larger
than I
expected. I trimmed another 1/8 inch from the cutout. This cutout
prevents interference from the bolt attaching the linkage
to the nose gear on
both sides. The co-pilot side needed a larger cutout. White primer was used
to show the marks after
each flight. I think this was transmitting a lot of
cowl vibration.
3) I sprayed white primer on the areas contacting the
baffling. I
found three hard hit areas and this is using the factory white powder coated
baffling. Two areas at
the front of the #5 cylinder needed bending away from
the cowl. Another area just above the oil cooler on the top side of the cowl
was hitting. The #5 EGT probe was hitting.
The #5 forward rocker cover was hitting on the bottom and was peened
about a
1/4 to match the form of the cowl. I removed the rocker cover to check for
clearance with the rocker arm.
4)
Baffling repairs were made to areas that were not tight against the
cowl. This significantly reduced the CHTs. I used
the cooling and
drag reduction data on lml from owners to help make small but helpful changes
in the baffling.
5) The prop
governor cable was a hard hit on the metal baffling and was
trimmed.
6) The nose gear doors had a slight overlap which was trimmed so
they close
tight with no gaps.
7) Both main gear inner and outer doors were adjusted to be flush and tight
when
retracted. This took a significant amount of time involving small hinge
adjustments and testing of each individual attachment link on
the outer doors
to get the right length before attaching both links for the final test. I say
this because the two links are
slightly different in length and geometry. I
found one was a little longer than required and actually twisted the door
slightly
open when both links were attached. This was not evident until I
retracted the gear using only single links.
8) the large
circular baffle behind the prop is cracked in two places and
remains that way until a fix can be made. This appears to be from a tight
fit
and needs to be measured for a new smaller piece. This is a large crack that
could easily be flopping around in flight and
somehow interfering with the
cooling process.
9) removed the quick drain for oil and replaced with the factory
plug.
I have lots of clearance and may put the quick drain back in.
The net result is now I have a smooth
engine compartment. My symptoms
included a difficult propeller balancing as we could never exactly home in on
a
solution. The vibration was small at 2700 rpm and takeoff but increased
significantly with rpm reduction. I attribute that
to the higher torque
twisting the engine closer to the left side of the baffling. The vibration
was evident in the cockpit, cowling
and when looking at the wings. The next
project will be to replace the silicone baffle with new material and replace
the circular
baffle plate behind the prop and replace the left side metal
baffle to better fit the cowl line near the #5 cylinder. Many thanks to
all
the suggestions that made this easier to do.
Paul Miller
N357V Legacy
RG
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