[f-AA] Auto-gas STC

[cgalley]

Nice summary BUT using autogas is less likely you need MMO as there isn't any lead to foul the plugs and stick the exhaust valve.

MMO is supposed to minimize the effects of TEL.

Cy Galley
EAA Safety Programs Editor
Always looking for ideas and articles for EAA Sport Pilot
  ----- Original Message ----- 
  From: John Rodkey 
  To: aeronca at westmont.edu 
  Sent: Friday, December 01, 2006 10:41 AM
  Subject: Re: [f-AA] Auto-gas STC


  Not very common anymore, since the addition of ethanol to most gas.

  Auto gas pitfalls:
   - stability - because of the additives, auto gas goes 'bad' after a while: avgas doesn't.  If you fly regularly, this shouldn't be a problem. 
   - safety - If you don't have a grounded delivery system, you're playing with fire, literally!
   - vapor point - at altitude ( 10K ?) the autogas, being more volatile, may result in vapor lock.  This is a perhaps disputable point - and probably moot for our Aeroncas at 1000 AGL, where many of us fly. 
   - effect on 'old' rubber hoses, carb parts. Alcohol is the big danger, but MTBE which was used for a while in CA before it was discovered to be more harmful than ethanol, has the same effect.  This is less problematic if you have recently replaced gas lines and have a steel needle in your carb. 
  - MMO - using autogas makes you more likely to use MMO, which we all know is bad (just kidding).

  There's a simple test to find out the percentage of alcohol in your gas: put a known amount of water in a tube with about 10 times as much gas.  Shake. 
  Let it settle.  If the apparent amount of water increases, you've got alcohol.
  Given a bit of precision, you could determine the exact percentage of alcohol,
  but I believe the STC for ethanol from Peterson specifies no alcohol, so even though the percentage may be low (I think they have to label gas if it has more than 3 or 4 percent),  you'll still be violating the STC.  And, of course, then you 
  become a test pilot.  Best done out over the Mojave desert, where there are 
  lots of places to put the plane down safely.

  John

  John


  On 12/1/06, Dwayne.Lafave at k12.sd.us <Dwayne.Lafave at k12.sd.us> wrote:
    How common is the use of auto gas in a 7AC?
    Any pitfalls one needs to be aware or if using auto gas?
    I know not to use ethanol, but have heard some concerns about lesser
    amounts of alcohol being added to gas without having to be labeled. 
    Would there b potential problems with that?


    Dwayne J. LaFave

    605-854-3151 (H)
    605-860-1650 (C)

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  -- 
  John (poobah) Rodkey - N9361E 11AC at Goleta 


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