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Smoking Spinner

N941WR

Legacy Member
I didn?t have this issue with the small engine (O-290) but with the new engine (O-360) and prop I would find aluminum dust on the prop and trailing behind the screws on the forward spinner bulkhead after each flight. (It shows up as smokey colored dust.)

It was bad enough that you could see the weave of the fiberglass in the aluminum bulkhead.

A friend suggested I put a light coating of silicone on the spinner where the bulkhead touches the spinner. I guess you could do the same with fiberglass but I was worried I would never get the spinner off again if I used epoxy.

100 hours later and no more smoking spinner and yes, I can get the spinner off.
 
When I first got my -6, it had a bit of looseness/gap in the front bulkhead to spinner too. I used some Permatex "Ultra Gray" silicone RTV and ran a bead all the way around the front bulkhead, then put a strip of Saran Wrap plastic around the bulkhead so the silicone would not glue the spinner on, then put the spinner on with a few of the back screws only, so that the gap between the bulkhead edge and the spinner would be filled perfectly.

After the RTV cured, I removed the spinner and used a single edge razor blade to trim the excess silicone away from the bulkhead, then to make sure there would be a tight, rubber-cushioned fit when finally assembled, I used my finger to rub a paper-thin layer of fresh RTV over the already cured RTV to build it up a tiny bit taller, and let that cure for a day or two.

Now the front bulkhead fit is nice and tight, with a RTV-cushioned fit where I have to push a slight pressure on the spinner cone to get the screw holes to line up.

BTW, I used the Permatex "Ultra Gray" gasket maker RTV silicone because it dries a little firmer than other silicone RTV compounds, in fact it's about as hard as Pro-Seal when it finally cures, and not "squishy" like ordinary silicone RTVs.
 
proper instalation of the spinner

should require lots of force on the nose of the spinner to get the screws to line up with the holes. If your setup doesnt require this consider adding a shim or washers between the fwd bulkhead and the prop. Idea is to move it forward just a little.
 
I simply use a few layers of duct tape around the edges the front plate.
This gives a "cushioned" pre-load on the spinner shell.
 
should require lots of force on the nose of the spinner to get the screws to line up with the holes. If your setup doesnt require this consider adding a shim or washers between the fwd bulkhead and the prop. Idea is to move it forward just a little.

Then the holes will not line up.
 
I tried Gorilla tape on mine before the RTV treatment, but in the hot Texas summer heat, the adhesive on the tape oozed too much and the tape kept creeping out from the gap and working its way backwards. I was also concerned about the weight of tape getting off-balance when it worked loose.

The RTV layer with just enough thickness to make it snug and need a mild push on the spinner cone to get the screw holes lined up seems to be working perfectly for me. Last oil change I took the spinner off to re-torque the prop bolts for winter weather temperature change and the RTV-to-spinner interface still looked and felt perfect after 50 hours of flying.
 
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