Hi,

I have a 2-1/4 aluminum spinner from MPI(Maxx Product International)
and have a TT Pro 46.
I broke in the TT Pro 46 and notice my spinner's shape changed as described in the picture. (The pic show the side view of spinner).

I think, the assembly of this spinner is no special.
It has prop nut with 2 different ends of thread(one for crankshaft and one for spinner's hex screw), the hex screw that goes to the middle of the spinner.

Is this normal ?? dangerous ?

Thanks.

No, it is not normal. Anything spinning at 12Krpm that is "not normal" is by default "dangerous".

Can you think of anything that would have damaged the spinner like that?

If so, I would replace the spinner, if not, I would replace it with a different make.

gus

I would not consider that normal...

Deformation of a metal spinner is usually a warning to get the thing off the engine before it spreads flying debris over a wide area.

I would contact the dealer you got the spinner from about getting a different spinner. If the dealer is no help... don't blame MPI for the dealer's response... Contact MPI.

I'm talking to MPI and I will just copy/paste the email.

[MPI]
Hi Jake,
No, it is not normal and it is dangerous. The backplate of the spinner should stay flat. According to your picture, it is buckled or pushed in. There are two ways for this to happen. First, the cone is over-tighten which bent the backplate. Second, the back of the propeller interfere with the rim of the backplate. When you tighten the prop, the blade hit the rim first before the hub set on the backplate. As you continue tightening the prop until the hub is set, the prop continue to push the rim and bent the backplate.

No matter what type of spinner you use, the prop should be in contact of the spinner at the hub only. the blade should be clear from the backplate and the cone. If the bent is slight and within the elastic limit of the material, it will bounce back one the the pressures is released. If the bent is beyond the yielding stress, the damage is permanent. You will need a new backplate. If you are not sure about the condition, it is safe just replace it.
Regards,
Jarvis Yeh
Maxx Products

[Jake]
Hi Jarvis,
Thanks for the reply.
You mentioned 2 possible cases how this happened.
The first case is not quite probable because I didn't tighten the screw that much
and watched carefully as I tighten it.

The second case,... I used Master Airscrew 11x6 and I'm not sure what "hub" you're talking about. Could u please specifiy ?
Thanks.
Jake.

The spinner should have had two "cut outs" in it that are meant for the prop blades to pass through. Sometimes the cut outs need to be enlarged to fit the prop, because they are not large enough and the spinner sits on the prop blades.

The spinner should NOT touch the blades of the prop.
Dennis-

I have been flying with a dented spinner for 2 years. I had to balance the spinner to make sure that it was not out of balance but it does have a slight dent. Seems to work fine at 7200rpm.

Even after much investigation, I still have no idea why the spinner deformed.
The prop was NOT touching the cone NOR the backplate.
I didn't overtighten the screw to bend the backplate.
Worse thing is that MPI stoped responding to my emails. []