Engine Mount Lock Washers

[theway]

My new mounts come with “shake proof” washers. They appear to be what’s called star washers. My question is how do I best utilize them?

Should I put them on the nut side of my old flat washers? Should I only use the new star washers and not use the old flat ones? Or do the star washers go together on one side as the attached illustration shows?

In summary what’s the best way to arrange these washers on new mounts?

Thanks again

[rbk]

Flat washer/star washer/first nut/second nut

[S/V Adeline]

From the picture of the mount, it looks like there will be one nut and nord washer below the engine bracket and one above, in that case you should leave out the flat washer.
With split or star washers, the nut and bracket are both gripped which prevents backing off, the flat washer has no grip and could allow the nut/washer combination to rotate over time.

[a64pilot]

One washer on either side of the engine side of the mount.
“Star” washers grip better, but have less material than a split washer and therefore are more susceptible to corrosion, so treat them with your favorite anti corrosion coating.

[tkeithlu]

Sneaky design in those Nordlock washers; I almost missed the small teeth that make it all work. But note the right hand part of image #1. It appears to be nut-star-engine flang-star-nut. That makes sense. A64pilot is saying that. Another point that makes sense is soft (blue) Locktite or two nuts, one for locking. Whatever will assure you that your engine won't go wandering. The clear part is that in thinking that through, you defeat the purpose of a locking washer of either type if you run it against a flat washer. Grip the parts that can turn.

[Cadence]

I'm just guessing. A lock washer goes under the nut, whether split of star. Split relies on tension star on friction. What is under it is the determining thing.

[a64pilot]

If you look at a split washer you’ll notice the split is at an angle, this forms an edge that digs in, you can often see where it’s dug in on parts when you remove something with a split washer.
The star washer is way more common on aircraft, I assume that is because they are more effective, but they have a whole lot less metal in them, so I’d assume they are more affected by rusting.

For this kind of thing I’m a fan of blue Loctite myself and unless I’m mistaken Loctite will seal a thread and if not prevent corrosion greatly discourage it.
I’d never heard of Nord washers and looked, and I don’t think they are star washers but something different?
https://www.nord-lock.com/nord-lock/products/washers/

Not sure star washer is the real name, but these people and McMaster Carr calls the star washer
https://www.almabolt.com/pages/catalog/washers/star.htm

Then this article says spilt washers don’t work, and it looks to be a convincing argument.
https://engineerdog.com/2015/01/11/1...out-fasteners/

[SaltyMetals]

For the same reason, but in a different application i was supplied with a pair of Nordlock washers to go under the nut for my feathering prop. No other washers at all to be added, just the pair of Nordlock. The boatyard where i changed my prop to the new feathering one with the Nordlock washers had never seen them before and insisted i signed a waiver, accepting responsibility.

Needless to say the rather expensive feathering prop never dropped off!

Conclusion? I would go along with the others who say to eliminate altogether the usual flat washer. All you need is the pair of Nordlock washers.

Andrew
"Genial Bee"