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Inverted Systems

rv8or

Well Known Member
This is a fairly old report that I came across today and it rang home with me.

I have had to rebuild my RV 3 engine due to corrosion issues in the crankshaft.
The engine is a O-235-F2B of 125 hp with an inverted system.
The first maintenance task a week after purchase was to pull the engine to repair a crack in the engine mount. It was quite a surprise when I undid the down pipe from the Tee piece of the inverted system to find it was full of water. After the engine mount repair I undid this hose at every 25 hour oil change and it was usually fairly full of water. At the next annual I pulled the crankshaft plug and found the crankshaft was beyond repair.
My opinion and only my opinion is that the metal Tee piece is acting like a condenser and dropping water down the inverted pick up hose.

My type of flying is only occasionally sportsman aeros usually +ve G. If the aircraft had been flown in hard aero's then this would not be so much of a problem.
For my flying I removed the inverted system to stop moisture build up.

So my advice is if you have a inverted system remove the drain pipe at every oil change to remove the water.

https://www.aibn.no/Luftfart/Rappor...rt-Attachments.Native-InnerFile-File&attach=1

Rob
RV3 G-BVDC
L4 Cub Share
RV8 in very very slow build
 
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