plastic crush washers on spinner?

[eman1200]

been flying a '75 F for 8 years now with no washers of any kind on the spinner screws, using several different mechanics.  new mechanic just put plastic crush washers on them.  that seems......odd to me.  what say you all?  tcds doesn't say anything specific about it.  checking parts manual as we speak.....

[Hank]

I use Teflon washers under screws that go against paint, but it's difficult keeping them on the spinner--whenever I remove a screw, the washer seems to drop to the floor and roll away. And with a 3-blade prop, there's a LOT of screws on the spinner!

[KSMooniac]

It is good practice... protects the spinner finish from the frequent R&R of the screws, and I think helps absorb some of the vibration and reduce the chances of cracking.

[N201MKTurbo]

Because we have always done it.

Nylon is preferred over teflon. It is much tougher and doesn't cold flow as much.

[N201MKTurbo]

 

 

[Hank]

8 minutes ago, N201MKTurbo said:

Because we have always done it.

Nylon is preferred over teflon. It is much tougher and doesn't cold flow as much.

I used Teflon because they're cheaper, and because there's less friction than taking them out. Primarily to protect the paint . . .

[N201MKTurbo]

https://www.digikey.com/en/products/detail/keystone-electronics/3129/315866

[eman1200]

5 minutes ago, N201MKTurbo said:

 

 

 

TYVM.  I guess I'm just surprised 2 mooney service centers didn't feel the need to add them and I also wouldn't have thought you could tighten them up sufficiently with the washers.  I'll be less nervous now, thank you.

 

[47U]

8 minutes ago, eman1200 said:

I also wouldn't have thought you could tighten them up sufficiently with the washers.

Do not over-torque spinner screws.  Hand-snug, that’s it.

[Greg Ellis]

My C model has never had them in the 20 years I have owned it.  I looked in the maintenance manual and parts manual and cannot find anything that references the need for washers.  The image that @N201MKTurbo posted, what model Mooney is that for?  I found references to the spinner in the parts catalog for my airplane but no reference to the use of washers under the spinner screws.   

[philiplane]

cracking and corrosion are big problems with spinners. That's why fiber or nylon washers are used. To allow some relative movement and relieve stress. And to insulate the aluminum from the stainless steel, to prevent corrosion. While stainless itself doesn't corrode, it is always electrically active. When placed against bare aluminum, and exposed to water, it will form a corrosion cell. Nylon washers should be used under all stainless fasteners, or the screws should be installed using wet paint or primer. 

The same goes for carbon fiber spinners. They have to be isolated from bare aluminum and stainless steel.

Edited Wednesday at 02:39 PM by philiplane

[eman1200]

12 minutes ago, philiplane said:

cracking and corrosion are big problems with spinners. That's why fiber or nylon washers are used. To allow some relative movement and relieve stress. And to insulate the aluminum from the stainless steel, to prevent corrosion. While stainless itself doesn't corrode, it is always electrically active. When placed against bare aluminum, and exposed to water, it will form a corrosion cell. Nylon washers should be used under all stainless fasteners, or the screws should be installed using wet paint or primer. 

The same goes for carbon fiber spinners. They have to be isolated from bare aluminum and stainless steel.

I would have thought the need for a snug fit would be more important for balance reasons.

[Aerodon]

Macfarlane supplies the at about $5 each:

 

https://www.mcfarlaneaviation.com/products/M1020-10/?q=spinner washers&search_type=product&index=6&page=1

[N201MKTurbo]

56 minutes ago, Aerodon said:

Macfarlane supplies the at about $5 each:

 

https://www.mcfarlaneaviation.com/products/M1020-10/?q=spinner washers&search_type=product&index=6&page=1

I think those are a gimmick, just use the nylon washers for Pennies each.

[N201MKTurbo]

1 hour ago, Greg Ellis said:

My C model has never had them in the 20 years I have owned it.  I looked in the maintenance manual and parts manual and cannot find anything that references the need for washers.  The image that @N201MKTurbo posted, what model Mooney is that for?  I found references to the spinner in the parts catalog for my airplane but no reference to the use of washers under the spinner screws.   

That was from the J manual.

[PT20J]

1 hour ago, 47U said:

Do not over-torque spinner screws.  Hand-snug, that’s it.

THIS^^^. Most people over tighten screws. The nutplates have an interference fit that retains the screws. Phillips screws cam out if over tightened..

[larryb]

They can also loosen up. Every couple of months I like to take a screw driver to them and make sure all are snug. On my previous Mooney I had a loose screw cause a lot of wear ruining the spinner. And the tightening order matters too.

[PT20J]

Nutplates wear out. If the screws lose torque, I might consider replacing the nutplates.