What are These?


Gyro Rehab Candidate
Those are the washer that go under your teeter bols on the right and left side of the aluminum hub blocks on your head.


Junior Member
My thick teter washers are just flat. They don't have the machined relief and I am not familiar with when or why Dennis did that. I don't see new washers in the mast support upgrade? Were these a change at the time Bravo went to market? What was the benefit or purpose of the relief?


Senior Member
Looking at the picture it is interesting that the bolt head is in the relief cut area.

Possibly to allow a shorter bolt?


Junior Member

Thanks guys. I see those were a production change when Bravo came out. It's the only "new thang" that's not included on my helicopter.
Why did Dennis feel like this was needed as a change?
* Maybe so the same bolt could engage a few more internal threads of the spuds

When the Bravo hit the market, Dennis believed the frame cracks were because owners flew them in an un-balanced condition and he had not
came out with the Mast Support kit yet. Most Bravo changes centered around trying to fix that. From memory, Bravos included:
* Cast aluminum pitch arms,
* Thicker tubing on some frame tubes
* A dynamically balanced centrifugal clutch
* Strut-Saver insert tubes to strengthen the landing gear legs
* Different preload in the blade cones
* New Track and Balance Charts
* Better Spherical Teter Bearings and these recessed washers
* Different MRGB Pinion Bearing arrangement (Two dual row angular contact instead of 3 or 4 single row)
* ??

I still don't see why these recessed washers could have helped with any of the problems.
Last edited:


Junior Member
Dennis Fetters just answered my question on why these two revised washers were introduced.

His explanation was that the cast pitch arms were bulkier than the stamped steel ones and there was a chance, that if the
cast arms were used, and if a large head-shift was needed to balance the rotor, the cast arms may have an interference
and scrub the bolt head. By allowing the bolt head to go 1/8" deeper into the washer counter-bore, interference with the
cast pitch arms is avoided, even if head-shift amount is large.