Originally Posted by
Kilgore Trout
Ryan, my understanding after checking the Petersen website it that the O-540 has been tested with auto fuel, but that the PA-32 airframe itself is not approved. The Petersen website has two routes to check, one for the engine, and one for the airframe. Did not check the EAA (who also sell Auto Fuel STC) for approved compatability with a PA-32 with an O-300.
Petersen website here-
Petersen Aviation
This is an interesting subject to me, mainly for the reason that Avgas in Juneau is horrendously expensive the last few years. It's above $5 a gallon there right now, and a couple of summers ago it was near $7 a gallon. Pretty painful in a Beaver burning about 25 gph. Had a very negative effect on my employer at the time.
I've got a PA-11 (C-90-8F) which I purchased the Auto Fuel STC for, and a friend has a C-172D (O-300C) who also did the same. Our problem is ethanol. The 11 has enough "soft" parts in the fuel system that I have never even been tempted to violate the STCs prohibition of fuel containing ethanol, and I hope my friend will avoid it also, as the old 172 has plenty of parts that I have concern about too. Things like fuel selector seals and o-rings. Those get goofed up and there might be a problem.
The concerns about future availability and price of 100LL and ethanol free auto fuel are big ones.
What would be the problem with burning ethanol so long as you burned it all right away? I hear that the main problems come from sitting in the tanks while in the hangar.
What about a mix of avgas and ethanol fuel?
Replacing a few O-rings is most likely cheaper than spending $3 a gallon more for 100LL. I read a story about a guy who had to replace all his rubber components after 1000 hours of flying on Ethanol. It sounds like a good deal to me. Why not fly the bad gas until things begin to leak then fix it? It seems like a cheaper way to go. Are new O-rings made to be Ethanol resistant?
Is there a simple way to chemically separate the ethanol out of the gas?
Skyhigh