I don't have the whole answer but I'm working on it. Here's what I do have.
Many Pawnees have been successfully using MOGAS for rmany years all around
the world, but.....

1. The Lycoming O-540 235HP engine has an STC for MOGAS in several
airframes.
- (The engine, propeller and airframe have to be STC'd together as a
unit.)

2. Some, but not all, Pawnee airframes with the Lyc O-540 have MOGAS STC's.
- Pawnee D airframe doesn't.

3. No MOGAS STC allows use of fuel containing ethanol - it does bad things
to aircraft fuel systems. Many, if not most, problems related to using
MOGAS have been traced to ethanol in the fuel.

4. There is an increasing number of reports of MOGAS containing ethanol sold
at airports for use in airplanes.

5. There is suspicion that ethanol is being added to gasoline earlier and
earlier in the distribution channel so that even if you have a deal with the
local petroleum distributor to deliver MOGAS without ethanol, he may still
unknowingly do so. Best advice is to test each batch of fuel for ethanol
before using it.

6. Many states or localities mandate special automobile fuel blends to fight
air polution. STC's for MOGAS do not take this into account.

So, while MOGAS can work fine in a particular Pawnee, the owner/operator has
to assume the responsibility to insure that all fuel used meets the STC
requirements.

Bill Daniels



wrote in message
...
Our club in Indiana is looking for advice and / or experience in
converting Pawnee Tow planes to run on motor fuel. Any comments or
advice would be gratefully accepted .