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Smith/Turbine Cub Wing Attach Fitting Alert!

Steve Pierce

BENEFACTOR
Graham, TX
I have not talked to Turbine Cubs as of yet but I recently removed wings on an early Smith Cub and found no bushings in the spars for the front wing attach bolts. The bushing is 3/8" O.D. and 5/16" I.D. There was some serious egging of the hole due to the 5/16" bolt moving around in a 3/8" hole. I just recieved a phone call from a friend building a recently purchased TCOW Cub and he had the same problem. Luckily he caught it in the pre-assembly stage. I would recommend everyone with a Smith/TCOW Cub kit check these front wing attach bolts for bushings in the spar as a failure would be catastrophic.
 
Thank You Steve! Good info to get out. Mine needs the bushings and will be ordering.
 
Hi Steve,
The D&E wing does not call for these bushings either, however their wing attach is a little different in that it has 4130 plates sandwiching aluminum castings and the spar itself. Is the Smith Cub different? Do you recommend bushings regardless? Thanks for the alert.
 
Steve,

Thanks for the heads up. We put them in when covering/assembling the wings. I can't imagine not putting these in as the aluminum would not last too long without them. However, to my knowledge there were no instructions to install them in the Smith "manual" at that time. Maybe they were shown in a drawing, but I don't remember that.
 
All the Piper wings and the Smith wings have aluminum doublers and I would install the steel bushings. With steel fittings I don't see any reason to.
 
ITSGBK,

I received a manual of sorts when I bought the Smith Cub from Canada.
It only consisted of a marked up L-21 WWII erection manual.

It was all I got with the plane. I depended on many resources to construct my plane. Much of it came from the great people at Legend aircraft.
 
Hi Gene
Thanks for the info. I also have the same manual.

if you don't mind Gene pm me at kbay@xyz.net. I like to talk to about your plane.

itsgpk
 
It has come to our attention that some early wings (Before Turbine Cubs of Wyoming, LLC purchased Smith Aviation) have been installed onto the airframe without the front spar bushing installed. There needs to be a 3/8” OD x 5/16” ID x 0.955” long steel (4130) bushing press fit into the hole located at the front spar attachment point to the airframe. Smith Aviation sent those bushings with the kit but did not want the wing manufacturer to install them. That was to be part of the builders 51%. It is very important that this bushing is installed on your wing! Once the wings are attached to the airframe you are not able to see if the bushing is present. This would not be caught by an inspector because he/she could not see into that location.
We are recommending that every Smith Aviation kit owner removes the front spar attachment bolt and checks inside the airframe attachment hole. If the bushing is present there will be a constant hole diameter all the way through the fitting. If the bushing is missing, there will be a definite enlargement in the hole through the wing spar portion. If you determine that the bushing is missing it is critical that you remove the wings and install the correct bushing. Turbine Cubs will gladly send you the bushings. All wings manufactured after the sale of the company to Turbine Cubs of Wyoming, LLC have had the bushings installed at the wing manufacturing facility.
 
Smith Cub Front Spar Bushing

I picked up my Smith Cub kit in October 2005. Nick provided the bushings for the front spar attach brackets and advised me to not forget them. I believe the bushings were itemized on his inventory list at that time. I installed them in the front spars on the wings.

Smith did not provide steel bushings for the rear spars. My interpretation of the Piper drawings and parts manual is that steel bushings were installed here as well. Has anyone noticed wear on the rear spar attach brackets? (Steve??)
 
I feel compelled to add that I had the pleasure to speak with the folks that own TCOW at SNF. They are a class act and dedicated to providing a top notch product and supporting same after the sale. The fact that they are being proactive on this issue says it all. They're putting heart and soul into making their company a success and certainly deserve our support.
 
Turbine Cubs said:
It has come to our attention that some early wings (Before Turbine Cubs of Wyoming, LLC purchased Smith Aviation) have been installed onto the airframe without the front spar bushing installed. There needs to be a 3/8” OD x 5/16” ID x 0.955” long steel (4130) bushing press fit into the hole located at the front spar attachment point to the airframe. Smith Aviation sent those bushings with the kit but did not want the wing manufacturer to install them. That was to be part of the builders 51%. It is very important that this bushing is installed on your wing! Once the wings are attached to the airframe you are not able to see if the bushing is present. This would not be caught by an inspector because he/she could not see into that location.
We are recommending that every Smith Aviation kit owner removes the front spar attachment bolt and checks inside the airframe attachment hole. If the bushing is present there will be a constant hole diameter all the way through the fitting. If the bushing is missing, there will be a definite enlargement in the hole through the wing spar portion. If you determine that the bushing is missing it is critical that you remove the wings and install the correct bushing. Turbine Cubs will gladly send you the bushings. All wings manufactured after the sale of the company to Turbine Cubs of Wyoming, LLC have had the bushings installed at the wing manufacturing facility.

You might want to check with Fisher in MO because his was purchased recently from you and the bushings were not installed.
 
Took one of my 2003 kit vintage, bolts out and I have bushings in mine. I seem to recall having them in a bag stuck to the wall for some time during construction. I do believe they were shipped in the same bag as the wheel spacer/bushings. I still appreciate the heads up on items like this. One never knows when he has missed something.
Thanks Ron
 
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