Grey sludge
I asked about this in class when we were going through something dealing with the lead contamination of oil. It only applies if the front cap has been removed from a hollow crankshaft and and the rear plug is inplace for constant speed prop operation. When I went to the blended airfoil propeller from Hartzell to replace the nonblended ailfoil propeller to gain the 3 kts of speed Van reported in RVator several years ago, I saw this gray sludge in the open end of the crank shaft that had the consistency of pudding. I did this for racing advantage and so did an RV-8 competitor Alan Carroll. In commication with Alan it came out that he saw the same thing. Fast forward a couple of years and I am in this class and we are talking about this grey sludge in the oil from the lead in the 100LL fuel. I had to ask about what I had seen in the crankshaft when I removed the propeller because I wanted to know about its effect on performance, SPEED. The instructor said it would have no effect on speed but it will affect the responsivness of the propeller to movements of the propeller control - it will slow down the pitch change but not limit the the pitch change travel. He said over time the lead will harden from this pastey state to more crusty form (I have only seen the thick pudding mass myself) and every 500 hours you should clean this out to restore the "like new" operation that you expect from a constant speed prop.
I completed the race in Cleveland, TX yesterday and I am currently in London, KY for a RON on the way back to Williamsport, PA to reassemble the class engine my lab partner and I disassembled Friday.
Bob Axsom
Last edited by Bob Axsom : 10-14-2012 at 09:13 PM.
Reason: London, Kentucky not Texas
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