Going to the elastomeric bearings was the biggest mistake Rotorway could have made. They had some problems with the bearing block design prior to the elastomeric. They used a flat thrust bearing that because of the design of the bearing block, the centrifical forces would pull the grease away from the bearing and sling it down the length of your main rotors.
About mid 80's, most of the european designs were going to the elastomeric bearings. But these were mostly the three and four bladed helicopters. Rotorway thought it would be a good marketing plan to change their design to follow suit. When they did that, they could truthfully say that they are the only american made helicopter that uses elastomeric bearings.
The issue with these bearings is first the cost. Currently, when you can get them, they cost $1500.00 a set. The second problem with these bearings is that time and temprature will deteriate the bearing. So basically, you can purchase a set of bearings from Rotorway and they might not be any good. You will only know when you install them and see how your rotor system behaves.
There was nothing wrong with their original design, besides the bearing block that housed them. If they would have simply reversed the end design, centrifical force would have kept the grease in the bearing and they would not have been running on dry bearings after a couple of minutes flying. Oh, and by the way, their tail rotor bearings are designed the same way. You have to drill a hole in the end of your tail rotor blades to let the grease have somewhere to go rather than building up and changing your static balance.
I am currently redesigning the bearing blocks to go back to a $25.00 thrust bearing, but reversing it so the forces keep the grease in the bearing for my Exec. I have a brand new set of elastomeric bearings, that are still in the plastic wrap from the factory, that has never been installed, and they are no good. Just because they sat on a shelf, in the heat for too long.
Now in my mind, if I pay $1500 for a set of bearings, even if it takes me 20 years to get around to mounting them, they should be just as good as when I first purchased them.
Rick