flyrotary@lancaironline.net Mailing List Archive

Mike,

Little black flakes sounds like it could possibly be small pieces of the fuel lines flaking off. I assume your fuel system returns unused fuel back to the tanks. You may want to set up a bench test to see if this is what's going on.

BTW, I believe that I was the one that stated that I have yet to find ethanol in any fuel samples. I stand by that statement as I routinely test each batch. And I haven't seen any warning labels on the pumps in my area, not that that means anything. Then again, who knows what changes may become
'mandatory" in the next four years in the name of saving planet earth. For now, I'll keep testing each batch.

Mark S.

P.S. Stay tuned for a DNA muffler update coming soon.

On Thu, Feb 26, 2009 at 9:59 PM, Mike Wills <rv-4mike@cox.net> wrote:

Well things seem a little slow today so how about re-opening a can of worms? We had a brief discussion a while back regarding ethanol in fuel. Frankly at the time I didnt know much about the subject but have been reading a little since I'm burning auto fuel.

At the time I think it was Al G. who said so far he hasnt found any auto fuel with ethanol in it. If I got that wrong I apologize. So far I havent found any auto fuel that DOESNT. As far as I can tell from my reading ALL auto fuel in CA has at least 6% and most is at 10% now.

Looks like the concerns are:

1) Vapor lock

2) Potential corrosion of aluminum components in the fuel system.

3) Deterioration of rubber (and other?) components in the fuel system.

4) Water.

5) Dislodging contaminants from previously used fuels.

I believe (hope?) the vapor lock issues to be a non-problem with our EFI systems. The potential corrosion issues seem to be overstated for ethanol, clearly a problem with methanol. All the hose in my airplane is Earls Perform-O-Flex which according to their website is "synthetic rubber". I assume they mean neoprene which I gather is ethanol safe. I assume the injectors themselves are safe? I thought Pro-Seal is also supposed to be ethanol safe. My airplane is new so there should be no issue with dislodged contaminants.

This leaves the issue of ethanol's affinity for water. Other than always keeping the tanks full to minimize airspace in the tank and condensation any ideas on how to deal with this other than hoping it doesnt happen?

I bring this subject up because for the second time since I've started flying I've found a little contamination during my pre-flight when sumping the tanks. Each fuel sample has a few ground pepper sized black flakes in it. Whatever it is it crumbles to powder between the fingers. The first time I completely drained the tanks and pulled the fuel filters and cleaned them. When I refilled the tanks I used a Mr. Funnel to make sure nothing bad got added. So whatever this is, its residual junk in the tanks from when they were built. Or its something (like ethanol) attacking the Pro Seal.

Any comments on ethanol in general or my fuel contamination issue are welcome.

Mike Wills

RV-4 N144MW