andrew phillips

andrew phillips

Well Known Member
For the first time today my prop ran backwards when I shut down the engine. As the engine slowed (close to stop) after pulling the mixture it suddenly hiccuped and the prob spun the other way. Should I be concerned? Also the engine seems to backfire occasionally. I am using a Performance injection system, slick mag and lightspeed ignition. I can't yet determine the exact set up to cause the backfire but it seemed to happen at the end of the taxi test runs as the plane was being turned around for the next run.
 
Well, I've got carb/magnetoed both sides, and have had it do the same thing in the early days of first runs. The mixture wasn't going all the way back into idol cut-off... so killing the engine with mags off, would cause it to sputter to a stop -hiccup- and spin the opposite way for a few revolutions. So I would say you've got a rich mixture problem of some sort. My $.02 Anyone else?
 
I can't say it would hurt anything, I've heard of AC engines running backwards for a short peroid of time with no ill effect....... unless you are not watching where you are going when you are backing up! :eek:

REVERSE! How come no one has added a full feathering / reversing prop so you can back up? Now that would be sweet!;)
 
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AFP utilizes a purge valve for positive mixture cut-off. Engine shut-down should begin with closing the purge valve and waiting for the prop to stop. Then complete your normal procedure. This will solve your "running backwards" problem.
 
some further information

Anyone who is following this thread might be interested in the following. I spoke to Superior today and they reminded me that with electronic ignition there is also a spark on the exhaust stroke which could have fired some unburnt fuel in the cylinder to cause the engine to run backwards. Also, I have said it before, but I will say it again, they have excellent customer service. I sent them an email with a question, they called me on the phone to answer it. I had a small oil leak and they picked up the cost of the replacement gasket and shipped it immediately. The leak is not their fault. Otherwise this engine runs so well that my test pilot for the first flight (who owns a 280hp Nanchang CJ6) commented on how powerful and responsive it was during our taxi tests.
 
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