Hirobofly
Heliman
Location: Horten, Norway
| Hi there.
For what it is worth...
I think the NTN-bearings will corrode/rust as fast as any other bearings if not treated correctly.
The key-word for corrosion in bearings is TEMPERATURE.
If you run your engines too rich, making them not reach proper operating temp, the bearings will only last perhaps a gallon or two.
Running high-nitro content fuel will make it possible to run too rich and still have power. The engine will not reach correct temp, and the burn will generate acid gases that corrodes the bearing (and crank, conrod-bushing, etc). I have had this happening after 3 tanks of fuel in a R90 with an OS90 C-spec.
The larger the engine, the "easier" it is to run the engine too cold.
Smaller engines like the OS50, is more difficult to run too cold, but possible with high nitro-content.
Also the additives in the fuel to prevent rust after it has been run will not function correctly if the engine did not have normal operating temp when stopped.
So, too lean engine will kill it. Too rich, and you'll kill the bearings.
Off course there are other factors as well, as storing the heli in humid conditions, flying in the rain, etc could also generate rust in the bearings. Also there are fuels with not so good oils, and this can also cause problems.
But, in general when someone struggle with rust/bad bearings with the same fuel/flying-conditions as other that don't have problems, the cause is too rich mixture/ too cold engine.
 RJ |
more power under load
