Well, the airplane RPM range is just around where the lightest bearing=20 loads are found. There was a chart on the other list about that. For the loa= ds=20 you might see, the bearing area is huge. The first bearing failure anyone wo= uld=20 be likely to see is a rotor bearing, and if it still has oil pressure, that=20= just=20 will not happen below 9,000 RPM. (Thus the need to lighten the rotors=20= for=20 long term use above 9,000 RPM.)The rather high weight of the iron rotor is=20 enough to load up the bearing to a point where the film strength of the oil=20= is=20 becoming important. Even then, the wedge oil temp is the culprit. The soft m= etal=20 overlay on the bearing has a very low melting temperature, and starts to mig= rate=20 away from the loaded area when over heated. This makes razor thin flakes alo= ng=20 the bearing edges. The bearing face will be bright and shiny rather than a d= ull=20 flat appearance of a new bearing. So those people who scream the=20 engine all of the time, machine off the overlay and run on the copper. The e= xtra=20 .0015" is just fine for additional oil flow and the copper is a great bearin= g=20 surface. It is however, far less tolerant of dirt bits in the oil.

The bottom line is: You cannot hurt it. Cool the oil, keep the oil pres= sure=20 at 71.5 (stock) pounds or better.

Run an air filter, and it will outlive you. Check for apex seal groove=20 wear at 100 hours, (through the exhaust ports) then after each 100 hour= s.=20 (annual).

Tracy should have a thought on the oil type if anything special is need= ed=20 for gear box support.

The Farm and Fleet store or, Tractor supply used to have Alnico magnets= =20 that they feed to cows to collect scrap metal that cows eat all of the time.= It=20 keeps the scrap in their first stomach where it dissolves. Put in a course=20 screen so the magnet cannot block the flow.

Lynn E. Hanover

In a message dated 3/25/2008 5:32:33 A.M. Eastern Daylight Time,=20 msteitle@gmail.com writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Lynn,=20

Thanks for the great summary on oil. I guess I should have=20 provided a bit more information on my first posting. This is a 3-rot= or=20 with a 2.85:1.0 RD2-C gearbox and an electric c/s prop. Normal engine=20 operating range is between 5200 and 7000 rpm with the vast majority of tim= e=20 spent in the 5000 - 6000 range. I may briefly hit 7200-7300 rpm on=20 takeoff roll, but that's only for a few seconds until the prop bites. = ;=20
Mark S.

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