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Re: N95598: Fuel Tank Surprising Discovery
I am pretty sure it was Ethanol free because the mogas has been there for several years. When I bought the plane in 2006, the previous owner had made a forced landing due to this stuff in the carburetor. I removed the carb, gascolator, and main fuel line in 2006 cleaned it all and flushed out the main fuel tank. (In hindsight... I did not consider that there could be stuff in the tank not passing through the finger strainer when flushed). I am pretty sure that the airplane sat for a couple of years with auto fuel before that time... so this stale fuel issue could go back to 2003 or 2004. I am not sure many gas stations around here had 10% ethanol that far back. So when I got the airplane back to my place I only put about 4 hours on it before I ended up having to park it due to other life priorities. The airplane then sat from 2006 until this year. Looking back, I think there was maybe 8 gallons in the tank... with half 100LL and half auto fuel mixture when it was parked on '06.
So... In April this year when Doc, Mark, Buell, and I started to work on the airplane the first indication of bad fuel was when one of us removed the tank cap. The first thing to hit us was the awful smell of rotten fuel. Next, we noticed that the steel float rod was nearly rusted apart. There was also a lot of rust around the interior ID of the tank filler neck. Some of the shellac was indeed gone from the float (but not enough to cause the mess we found). The cork was not degraded.
Again, the gascolator was removed and cleaned. Did not remove the carburetor, but checked screen and drained the bowl and did not find it to be dirty. Again, the tank was flushed several times with about 5 gallons. All of the bad fuel was removed and fresh 100LL has been used exclusively since then. I have a new cap/gauge from wag aero.
So the day all of the additional contamination was found came after flying for approximately 8 hours. My conclusion is that the contaminant was mostly flakes of varnish from the rotten car gas. Some was probably shellac. And there is some rust, but not as much rust as varnish flakes. These flakes when dried out turn to powder or can poof away with the slightest breath of wind. I feel certain that we got most of this stuff out, but plan to continue watching the gascolator and to repeat the siphon (vacuum) process again in a few weeks. And I am keeping avgas in this airplane.
By the way... when it was overhauled the upper cylinder parts were replaced with parts designed for low lead.
I am pretty sure it was Ethanol free because the mogas has been there for several years. When I bought the plane in 2006, the previous owner had made a forced landing due to this stuff in the carburetor. I removed the carb, gascolator, and main fuel line in 2006 cleaned it all and flushed out the main fuel tank. (In hindsight... I did not consider that there could be stuff in the tank not passing through the finger strainer when flushed). I am pretty sure that the airplane sat for a couple of years with auto fuel before that time... so this stale fuel issue could go back to 2003 or 2004. I am not sure many gas stations around here had 10% ethanol that far back. So when I got the airplane back to my place I only put about 4 hours on it before I ended up having to park it due to other life priorities. The airplane then sat from 2006 until this year. Looking back, I think there was maybe 8 gallons in the tank... with half 100LL and half auto fuel mixture when it was parked on '06.
So... In April this year when Doc, Mark, Buell, and I started to work on the airplane the first indication of bad fuel was when one of us removed the tank cap. The first thing to hit us was the awful smell of rotten fuel. Next, we noticed that the steel float rod was nearly rusted apart. There was also a lot of rust around the interior ID of the tank filler neck. Some of the shellac was indeed gone from the float (but not enough to cause the mess we found). The cork was not degraded.
Again, the gascolator was removed and cleaned. Did not remove the carburetor, but checked screen and drained the bowl and did not find it to be dirty. Again, the tank was flushed several times with about 5 gallons. All of the bad fuel was removed and fresh 100LL has been used exclusively since then. I have a new cap/gauge from wag aero.
So the day all of the additional contamination was found came after flying for approximately 8 hours. My conclusion is that the contaminant was mostly flakes of varnish from the rotten car gas. Some was probably shellac. And there is some rust, but not as much rust as varnish flakes. These flakes when dried out turn to powder or can poof away with the slightest breath of wind. I feel certain that we got most of this stuff out, but plan to continue watching the gascolator and to repeat the siphon (vacuum) process again in a few weeks. And I am keeping avgas in this airplane.
By the way... when it was overhauled the upper cylinder parts were replaced with parts designed for low lead.
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