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JHOSLER(at)epri.com
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 Posted: Sun Jan 29, 2012 1:32 pm Post subject: Ground straps AA-5A |
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I have been having significant static on the radio when flying in rain. I suspect static charge build up on rudder (I can hear the rudder strobe in the static).
I cannot find a ground strap connecting the rudder to the vertical stab or fuselage.
A ground strap is mentioned in the maintenance manual (part of rudder removal procedure).
Can someone tell me where this ground strap is supposed to be located??
Thanks!
John
704-252-0780
From: owner-teamgrumman-list-server(at)matronics.com [mailto:owner-teamgrumman-list-server(at)matronics.com] On Behalf Of Gary Vogt
Sent: Sunday, January 29, 2012 2:02 PM
To: teamgrumman-list(at)matronics.com
Subject: Ground straps AA-5A
to be honest, I don't recall. All I know is that when I looked at the plane, the damage was like the NTSB says with the exception of the entire end of the torque tube gone. I was only there for about 20 minutes before there were FAA and NTSB people all over. No cell phone cameras then.
From: FLYaDIVE <flyadive(at)gmail.com>
To: teamgrumman-list(at)matronics.com
Sent: Sunday, January 29, 2012 8:43 AM
Subject: Re: Aileron mass balance
Gary:
Pictures would have added a lot to the FMA.
You mentioned that the torque tube was sheared? Not crushed or deformed.
Two thoughts come to mind:
1 - Where was the shear, was it inline with the torque tube bracket? As if the bushing was cut through by friction and the friction was all around the torque tube diameter?
2 - Was the bushing still there and if so, in what condition?
It is extremely difficult to shear a tubular object. I have never seen it done without deforming the tube shape. It would be very easy to consider the tube being worn through and the bushing missing. You can shear an 'I' beam but not a tube.
My money would be on a highly worn or missing bushing. And then the question becomes: Wasn't this ever checked during Annual?
Barry
On Sun, Jan 29, 2012 at 1:53 AM, Gary L Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:
I appreciate the lessons in strength of materials and statics, but it's more than just a missing counterweight. I wish I'd taken pics. The end of the torque tube was sheared at the aileron bearing bracket. That degree of force has to be transferred to the aileron stop, if and only if, the bolt that does the stopping is still there.
Gary
Sent from my iPad
On Jan 28, 2012, at 7:08 PM, Gary Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:
| Quote: |
OK, but, to get the weight into the slipstream far enough to get dragged on, it has to move past the stop. Otherwise, there would be a lot of torn off weights.
From: James Grieco <jamesgrieco(at)yahoo.com (jamesgrieco(at)yahoo.com)>
To: TeamGrumman <teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com)>
Sent: Saturday, January 28, 2012 5:50 AM
Subject: Aileron mass balance
--> TeamGrumman-List message posted by: James Grieco <jamesgrieco(at)yahoo.com (jamesgrieco(at)yahoo.com)>
I think there is a misconception about the weight. Its specific job is as a mass balance about the hinge line. If you draw a free body diagram of the aileron with the weight and a chord wise cut of the aileron, the two masses balance around the hinge bracket. When you apply a vertical gust, the inertia load on both sides of the hinge is the same, and in the same direction, so the hinge bracket gets wacked with combined load of the aileron mass + the counter weight mass X the vertical gust factor. This means the aileron wouldn't rotate, but there would be a large bending moment at the junction of the weight to tube welded joint. With rust and continuous fatigue loading it could break. Since no aileron rotation occurs, the rod would not hit the stop.
An estimate of the Max load and rod stress seen can be found by determining the ultimate capability of the hinge bracket. Since I gather it did not fail, the bending moment applied to the rod would be 1/2 the bracket ultimate load capability X the length of the rod to the CG of the mass. The gust factor would be 1/2 the bracket ultimate load divided by the weight of the counter weight upamGrumman-List" target="_blank">http://www.matronics.com/Navigator?TeamGrumman-List<========================
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flyv35b(at)minetfiber.com
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| Posted: Sun Jan 29, 2012 1:42 pm Post subject: Ground straps AA-5A |
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On 1/29/2012 1:29 PM, Hosler, John wrote:
| Quote: | I have been having significant static on the radio when flying in rain.
I suspect static charge build up on rudder (I can hear the rudder strobe
in the static).
I cannot find a ground strap connecting the rudder to the vertical stab
or fuselage.
A ground strap is mentioned in the maintenance manual (part of rudder
removal procedure).
Can someone tell me where this ground strap is supposed to be located??
Thanks!
John
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It's about 10in. or so above the bottom rudder bearing, on the very
front of the rudder. Turn the rudder to the stop using TWO hands and
you might see it.
Cliff
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JHOSLER(at)epri.com
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| Posted: Sun Jan 29, 2012 1:52 pm Post subject: Ground straps AA-5A |
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Great thanks!
Sounds like replacement will require removal of the rudder.
John
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flyv35b(at)minetfiber.com
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| Posted: Sun Jan 29, 2012 3:19 pm Post subject: Ground straps AA-5A |
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On 1/29/2012 1:49 PM, Hosler, John wrote:
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Great thanks!
Sounds like replacement will require removal of the rudder.
John
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Not totally. The beacon wire will prevent you from totally removing it
and you don't want to fish that out and back in. Remove the rudder
cables by first cutting 3/4" thick blocks of wood and wedging behind the
copilot pedals to bring them aft until there is slack in the cables.
The you can remove the two flat head screws that hold the top bearing
mounting plate and then raise the rudder up out of the bottom bearing so
you can rotate it and get at the rivet and ground strap. It can hang on
the top plate and wire it to the vertical fin if you are careful. Might
as well go ahead and replace the lower rudder bearing while you have it off.
Cliff
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