WTB: LWA9 bushings

[Robert M]

Hello,

Does anyone have extra LWA9 wing attach bushings they could sell? Need 9 pcs. I emailed Cozy Girrrls and am not receiving a response.

During the most recent inspection found a few of them worn out of tolerance and looking to get back flying. I will share updates on the repair process with the community.

Thanks!

Rob

Long EZ 329W

Edited May 19 by Robert M

[Marc Zeitlin]

1 hour ago, Robert M said:

During the most recent inspection found a few of them worn out of tolerance...

What was the tolerance that you found them worn out of, and where did you find that specification?

[Robert M]

0.015" bolt-to-bushing clearance

Plans pg 19-18

Know a source for any LWA9s? :)

[Kent Ashton]

5 hours ago, Robert M said:

Know a source for any LWA9s?

Seems to be a common complaint that CozyGirrls don't answer their mail.  I see two email addresses on their website   http://www.cozygirrrl.com/aircraftparts.htm  i.e, CGParts@aol.com, cozygirrl@aol.com   There is also a phone number and address on the bottom of their "Release" page too.

I am wondering if bronze bushings would do.  Those are available in lots of sizes.

[Robert M]

Although galvanic corrosion generally supports use of bronze, I'm reluctant to use a different material than stated in the plans.

Thanks to Kent's reply, I was able to reach CG by phone, and they do not have LWA9s in stock. Funny enough they suggested asking Marc. I'll go to the local machine shop and online CNC stores and get a quote to have a batch made. Anyone else need some? I can add some to the batch.

Cheers

[Marc Zeitlin]

3 hours ago, Robert M said:

...Funny enough they suggested asking Marc...

That is slightly funny.

So the specification for the ID of the LWA9 bushings is 0.500" +/- 0.001". I have no idea why that tight a tolerance was chosen. You stated that the tolerance was 0.015", which it is not.

Now, the issue here is that AN-8 bolts have a maximum shank diameter of 0.499". The minimum ID of the bushing is stated to be 0.499". Anyone see a problem here?

As a mechanical design engineer, knowing the design of the wing attach fittings and the way that the loads are transferred, as well as the tolerancing of the AN-8 bolts, I'd modify the design of the LWA9's to have an ID of 0.500 +0.003" / - 0.000". This way, ANY AN-8 bolt will fit, rather than just most of them.

With respect to machine shops, I've had excellent service from online shops Xometry.com and Hubs.com. Easy online quoting, ordering and delivery - submit a 3D and 2D file and you're off and runnning.

While I have designed and am selling (for a while anyway) electric nose gear components and other nose gear components that work with 3:23 Composites' nose gear forks, I do not have any/all Long-EZ COZY parts designed and in stock. Maybe eventually...

[Robert M]

Good thoughts, thanks for sharing. I'll update the geometries that I send for quote.

As a fellow engineer, I am compelled to reply to your assertion that the tolerance is not .015". See the Note at the bottom of pg 19-18 "..the tolerance on fit of bushing-to-bolt is not real [sic] critical...Even a .015" clearance ("slop") is acceptable and safe." Speaking to bushing-to-bolt tolerance, as opposed to part mfr tolerance.

Cheers

[Marc Zeitlin]

2 hours ago, Robert M said:

... See the Note at the bottom of pg 19-18 "..the tolerance on fit of bushing-to-bolt is not real [sic] critical...Even a .015" clearance ("slop") is acceptable and safe." Speaking to bushing-to-bolt tolerance, as opposed to part mfr tolerance.

Interesting - you're right, in both the LE and COZY plans. So both Nat and Burt (both engineers) draw a part with a +/- 0.001" tolerance, and then say "nevermind - we don't actually give a crap what the fit is". Which is definitely the case - a sloppy fit is NOT a problem. But why have 0.001" tolerance on the part drawing. That's just bad engineering, and makes the part cost more than it needs to.

All I was looking at was the drawing. Thanks for the pointer.