Ethanol in Airplanes

[GAHorn]

Well, keep in mind that except for the ragwings there is no pump in the 170 series, so gravity is the only impetus for fuel to flow. High engine consumption rates don't increase fuel flow beyond what gravity can impart. A huge slug of water, trying to settle downhill against fuel flow will probably slow the progress of the fuel towards the engine.
It's all speculation on my part, but I would guess that a fuel line filled to the brim with water would impede the flow of fuel somewhat. Would it do so sufficiently to make the engine cough or quit? Maybe.
But you certainly should find a lot of water in the gascolator following the flight, I'd think. Water, once in a gascolator, doesn't get out except thru the drain until the bowl is completely full and then it goes thru the carb,...but the bowl should remain full of water til the flight's over, one way or the other.

[zero.one.victor]

.... A huge slug of water, trying to settle downhill against fuel flow will probably slow the progress of the fuel towards the engine.......

Huh? If we're talkiing about fuel & water in the fuel lines,I can't imagine the water wanting to flow upstream/downhill & impeding fuel flow. It's gonna flow right along with the fuel,like any other fluid. It would only flow downhill when at rest,in a no-flow dituation. IMHO.
Also,tell me more about adding a quick-drain to the bottom of the fuel selector. this is inside the belly,correct? So how do you quick drain the quick-drain> Have to pull an inspection cover off? The where does the fuel go--in the belly? Or do you add a drain line to route it to the exterior?
I'm confused...

Eric

[JJH55]

I was visualizing that the low point in the system might capture water that might not escape until the aircraft was in level flight or in a nose down attitude. I confess, I dont know how much fuel capacity is in the selector valve assembly but would imagine it's more than merely whats in the fuel lines that converge there. If there isn't, then would another drain really be worth the trouble? Perhaps the better solution is to drain two times more gas from the gascolator (with the fuel selector to the "on both" position) than its capacity at preflight to insure the lines are clear. Sure sounds alot more reasonable than the cost/work of installation, the STC, leaks, potential damage from rocks etc. Course a belly drain would come in handy for the belly cleaning parties...

JJH55

[GAHorn]

Huh? If we're talkiing about fuel & water in the fuel lines,I can't imagine the water wanting to flow upstream/downhill & impeding fuel flow. It's gonna flow right along with the fuel,like any other fluid. It would only flow downhill when at rest,in a no-flow dituation. IMHO.
Also,tell me more about adding a quick-drain to the bottom of the fuel selector. this is inside the belly,correct? So how do you quick drain the quick-drain> Have to pull an inspection cover off? The where does the fuel go--in the belly? Or do you add a drain line to route it to the exterior?
I'm confused...

Eric

If the fuel selector is between the gascolator and the fuel tanks, yet also below the gascolator, .... then when that low point is filled with water...how will the water go uphill to the gascolator? Ans: when the fuel flow is sufficient to force fuel uphill more rapidly than the water can flow downhill, ...or when the aircraft is rotated to a more nosedown position such as in descent. But we already know that fuel flow may not always exceed the "descent" rate of water,...so water will remain puddled in the fuel valve. When that water is of sufficient quantity, it's "turgor" (surface tension - think of it as a glob of water trying to remain in a glob...) will become a restriction to fuel flow.
That's why a gascolator works. It allows the water to settle to the bottom of the gascolator bowl where it will not become an impediment to fuel flow. But if the gascolator becomes full of water then the water will be pushed along by the fuel, except that when it enteres the smaller diameter fuel line,...being heavier than fuel,....it will resist upward travel and impart a restriction to fuel flow. At least it will until it breaks up into smaller "globs"...but that means the fuel flow has to overcome the water turgor...another restriction to fuel flow.
Only the later fuel selector valves are equipped with a drain plug. (B-models subsequent to sn 20285, or those earlier airplanes that have been converted.) The quick drain is like the Curtis quick drains in the wing roots. Rather than have to remove a AN913 plug to drain the selector valve periodically, a quick drain allows the operator to drain it during preflight.
The aircraft sn's 202386 and later all have access holes for the drain plug already installed beneath the selector valve.

[Joe Moilanen]

I probably should have waited for the STC for the quick drain at the fuel selector location but when your engine starts coughing at 500' on takeoff with nothing but trees below I'll take my chances with getting caught.

Joe

[GAHorn]

I probably should have waited for the STC for the quick drain at the fuel selector location but when your engine starts coughing at 500' on takeoff with nothing but trees below I'll take my chances with getting caught.

Joe

You should have another opportunity soon. The paperwork was submitted this week, according to the STC developer. Existing STC'd drains for 172's are priced affordably (at least as affordably as any airplane or boat part can be) -- at about $25.

[Dave Clark]

George
Would you keep us advised and who to contact to buy the STC please?

[Joe Moilanen]

One of the things I've also got out of the selector quick drain is sediment that otherwise would eventually would make it's way up the system just to add to what has already collected collected at the gasculator. I always drain at the selector drain before the gasculator to catch it before it could get "flushed" up.

Joe

[GAHorn]

George
Would you keep us advised and who to contact to buy the STC please?

As soon as the STC holder (Skip Cardell) notifies me I'll let you all know about it. (I knew he had such an STC for the 172 and others and I had contacted him to inquire as to whether he had an STC for the 170, he didn't, so we consulted for development of the STC. I've supplied him with the technical support regarding the selector valve and the aircraft relationship status to the other STC's he has. Mr. Cardell promises to keep us appraised and he knows many of us be interested.)

[vmoura]

For those of you who do not have experience with etanol as fuel here it goes. Engine compression is a little bit biger than a gasoline engine. It burns a little bit more fuel. The big problem is that ethanol is corosive. It will eat even carburators specially treated for ethanol. What I was told that in Brazil some GA pilots are already using it in place of Avgas. It costs 5 times less. If a lot is flown could easily justify changing all fuel system parts every so often. I was told that the fuel tanks and fuel lines are changed to inox steel ones to minimize corrosion.


From Aero-news:

Ethanol Powered Airplane Certified In Brazil
Fri, 18 Mar '05

Renewable Fuel Powers Crop Duster
Depressed about the high price of aviation fuel? Don't turn to drinking to drown your sorrows, you may need that ethanol to power your aircraft in the future. Neiva delivered an ethanol-powered crop duster to a customer at a ceremony held in Botucato, Sao Paulo on Tuesday.

The airplane is named the Ipanema, which has been in production for more than 30 years. The plane was the 1000th unit of the type, and is the first production aircraft in the world certified to use ethanol as its fuel. The company, Industria Aeronautica Neiva, is a wholly owned subsidiary of Embraer. They produced 83 Ipanemas last year, and 46 in 2003.

Neiva received the type certificate for an alcohol-fueled aircraft in October 2004. Brazil is a major producer of ethanol, produced from sugar cane. It has been used in their automobiles for more than 20 years. Gasoline is up to five times more expensive than ethanol, pollutes more, and is not renewable.

Company officials claim their ethanol-powered engines are more durable and seven percent more powerful, according to media reports. Neiva has over 100 orders to convert already flying aircraft to the new engine. The Brazilian government expects that more small aircraft will be converted to ethanol in the future to conserve oil-based fuels

[GAHorn]

Just as a reminder, ...from page one of the Cessna 170 Type Certificate:
"WARNING: Use of alcohol-based fuels can cause serious performance degradation and fuel system component damage, and is therefore prohibited on Cessna airplanes."
It makes no difference what they do in Brazil with regard to our own airplanes until Cessna changes their TCDS or an STC is approved for the use of alcohol.

[blueldr]

Since the removal of the additive MTBE from all the mogas in California, all of the brands that I have tested check out at between 5% and 7% alcohol. I do not know wether it is ethanol or methanol. Whichever it is, it seems to work fine in my airplane, and I have not noticed any increase in sump water. I normally test each batch that I get for volitality and alcohol and I've never found any fuel that I felt was unsuitable. I do make a point of buying my fuel at high volume service stations so that I'm likely getting the freshest product. I have found no difference among the various
national brands.