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Airpath compass mount


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We just got a new compass mount (plastic piece inside which the compass mounts) for our airpath compass mounted to the vertical beam in the middle of the windshield. This plastic piece seems to do its job well enough, but there is a thin sheet metal u-shaped piece that attaches the plastic mount to the metal tube/strut, and this metal piece causes the plastic mount and compass assembly to vibrate quite badly. Is this metal attachment original? Are there other part options? If this is common are there folks that have had luck with modifying or damping the mount attachment to reduce compass vibration?64af8498cded276fbf7ffc6540ece4a9.jpg

 

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That piece of metal is not original.

And...

It probably isn’t the source of vibration either...

When I had bubbles forming in my new vibrating compass...

I added some soft rubber to separate the compass from the plane...

The tighter the screws, the more the vibration...

Loosening the screws kept the signs of something bad from not being extra visual...

My O360 had broke its engine mount...

180hp pulling 2k LBs of plane around the sky, using only three bolts instead of four...

What I’m saying... check what may be generating a higher level of vibration than usual...  your compass might actually be trying to tell you something? The engine is bolted to the airframe about a few feet from the compass... could be a rubber engine mount has been crushed or broken or something hard is bumping against something moving... or the prop may be out of balance for some reason like missing a spinner part(?)  all just speculation...

PP thoughts only, not a mechanic...

Best regards,

-a-

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Normally the compass is mounted directly to the tube with long brass screws and nuts which pass through the tube.  Once mounted correctly, see how the vibration is.

 Anthony raises a valid concern, engine mounts do break, old mounts sag allowing the exhaust system to contact the cowl transmitting vibration to the airframe.

Clarence

 

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Okay getting the picture that our compass mount isn't original or proper. Does someone have a pic of this style of compass mount properly done? Was the airpath compass original equipment for the 68 M20F? If so, per Clarence's description, shouldn't there be two front-to-back through holes in the windshield tube/strut to accommodate the mount screws?

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36 minutes ago, moontownMooney said:

Okay getting the picture that our compass mount isn't original or proper. Does someone have a pic of this style of compass mount properly done? Was the airpath compass original equipment for the 68 M20F? If so, per Clarence's description, shouldn't there be two front-to-back through holes in the windshield tube/strut to accommodate the mount screws?

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https://www.texasairsalvage.com/main_view.php?editid1=203663

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The 65C has the two holes... set front to back in line with the standard airpath compass...

Mounting a flat surface on a round surface leaves a lot of flexibility for shaking left to right...

See if airpath has some options for mounts...

https://www.airpathcompass.com/J30/index.php/catalog/commercial/c-2200/c-2200-l4-1-detail

Unfortunately I had difficulty navigating the site via phone...

they have a few options for cases, voltage and other things... and maintenance items... ASpruce May have better details...

Bryan’s pic, and Marauder’s link show what appears to be a skirt that makes the mount look nicer at the tube/flat surface interface...

The OP has an interesting situation of sideways screw holes...

other things... brass screws and brass acorn nuts painted black make things a little more functional and complete...

Best regards,

-a-

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