Spinner screws break!!

pierre smith · #1 12-21-2006, 06:19 AM

Mornin' all.
I installed three nutplates in the forward spinner plate (after a year without any), between prop blades and used # 8 screws with countersunk Tinnerman washers. After about four or five hours of flying, two of the screws broke off in the holes and damaged the leading edge of the prop.

I didn't overtighten them either so I installed new screws and on the way back from Florida a few days ago, two had broken off in the holes again........sheesh!

What have you guys done? More screws? Bigger ones? What gives anyway?

I have been advised to paint a thick mix of resin and mill fiber on the inside of the spinner where it contacts the front plate and re-install it so it'll make a "bed" stopping any loose motion. Whaddya think?

Miffed,

roadrunner20 · #2 12-21-2006, 06:59 AM

Hi Pierre,
I have the same setup with the 3B Catto.
I believe I'm using #6 ctrsink with the tinnerman washers on both spinner plates and have had no problems after 33 hours. I've been keeping a close observation that they are snug but that is all. I've only had a few that have become loose enough for me to re-snug up. I believe I have 2 screws between each blade space. I'll check when I get to the hangar later this evening.

Kahuna · #3 12-21-2006, 07:02 AM

Pierre,
I advise scuffing the plate, grease the spinner in the area, and apply a bead of proseal to the plate and install. You dont need any screws there as you already know. If you put some back, this should elievate the problem.

I have no screws showing on my vans spinner. Only screws through the backplate into the spinner to a flange I fiberglassed in that no one can see.

I can attest that on my installation, no screws necessary on the fwd bulkhead. But I would put the bead in there regardless now that you know there is some play. I recommend this be done regardless of whether any screws are used or not. I have seen this issue before that you are experiencing now.

Best,

Ironflight · #4 12-21-2006, 07:09 AM

Quote:

Originally Posted by Kahuna

I have no screws showing on my vans spinner. Only screws through the backplate into the spinner to a flange I fiberglassed in that no one can see.

Dang - that sounds neat Kahuna! I had never thought about doing a spinner with no screws visible, but just reading your sentence made it clear exactly how you did it - almost makes me want to order a new spinner just to have a project! Very cool idea...

Paul

pierre smith · #5 12-21-2006, 07:50 AM

Thanks Kahuna...sounds like a neat fix and I'll eliminate the forward screws.

Paul, you sound as though you're suffering from builder's withdrawal as I am. I really miss not having anything to build now that I'm flying...

Regards,

Kahuna · #6 12-21-2006, 07:50 AM

Hey I wish it were my idea.

The "screwless spinner" idea came from Rick Gray who stole it from someone.... dont know who, maybe on the RV-List. You would not believe how many builders walk up to my plane and see that spinner and say "Where the $#@! are the dang screws. It looks cool, always gets a raised eyebrow from builders(my favorite part), and makes bug cleaning and waving easier.

Easiest to do while your mounting for the first time, but can do anytime. Ill tell you what, give me a half hour or so and Ill post pics and a web page.

Best,

Kahuna · #7 12-21-2006, 08:20 AM

OK Here you go. Pics and a webpage. Enjoy,
Kahuna's Screwless Spinner

Bob Axsom · #8 12-21-2006, 08:36 AM

Pierre, on the forward mounting holes, what is their configuration? Are they drilled for the screws and countersunk or are they 3/8" diameter to allow the dimple of the washers to go into the hole and secure the spinner by clamping action only?

Bob Axsom

pierre smith · #9 12-21-2006, 09:33 AM

Hi Bob,
I used a countersink on the spinner so that the Tinnerman washers lay flush against the spinner. The proseal is drying as we speak

No more forward screws either.

Regards,

Bob Axsom · #10 12-21-2006, 09:58 AM

Just to clarify your former installation, the hole was actually drilled for the screw and countersunk to accommodate the dimpled washer so any latteral force could still be absorbed directly by the screw. This is still a hard mount with no shock absorbing features provided by the dimpled washer. This is perhaps important for others in the field with similar installations and current builders to know.

Bob Axsom