B

blueline

I'm New Here
Hi all,

Just have a simple question about a mistake I made the other day. I've got a Lycoming IO-540 on an RV-10. Every time I shut down, it's the same thing: all electronics off, then fully lean to kill the engine, then key off in the ignition.

But the other day, for some reason "nobody knows," I had started back up for a quick test of an instrument (after having flown a good bit already), just to check it, then turned off the ignition FIRST. I hadn't leaned yet to shut down. Actually I hadn't shut off my electronics either. Off went the engine of course but I only leaned it right as/after that.

Would there be any cause for concern after my having blundered this way, particularly any issue with fuel/engine? Never, ever done that before, and it's like for a moment I thought I was shutting off my car or something (via the keys instead of lean-to-kill). I had to slap myself for it.

Just want to know if that could have any ramifications or if, rather, just "don't do it again" and move on.
 
Mags first

Not an issue, not really bad at all. There are still a lot of planes that can't be leaned out to shut off. It is better to run the fuel out, but no harm no fowl. That being said, if you were in the middle of a mag check at 1800 rpm and you shut off the ignition, it's best to just let it die and restart. If you turn the ignition back on, the engine is continuing to suck fuel when the plugs quit, then you turn it back on with cylinders full of raw fuel it could lead to a back fire, which I have been told could, in extreme condition remove a cylinder.
As our brothers from down under say, no worries mate.
 
Welcome to VAF!

Dale, welcome aboard the good ship VAF:D

Another 10----------sweet;)
 
SportAvServ said:
Not an issue, not really bad at all. There are still a lot of planes that can't be leaned out to shut off. It is better to run the fuel out, but no harm no fowl. That being said, if you were in the middle of a mag check at 1800 rpm and you shut off the ignition, it's best to just let it die and restart. If you turn the ignition back on, the engine is continuing to suck fuel when the plugs quit, then you turn it back on with cylinders full of raw fuel it could lead to a back fire, which I have been told could, in extreme condition remove a cylinder.
As our brothers from down under say, no worries mate.
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Thanks! Suspected this but was hoping for reassurance. I appreciate it!
 
pierre smith said:
You're more likely to blow a muffler apart than hurt a cylinder.

Best,
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Generally, only if you try and restart it before the prop has stopped. This is caused by unburned air-fuel mixture going out the exhaust valve and "igniting" if the ignition is immediately turned back on--erroneously described as "backfire". However, this is the procedure some use to test mag grounding, minus the "after-burn" of course. YMMV....
 
pierre smith said:
You're more likely to blow a muffler apart than hurt a cylinder.

Best,
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True that, Pierre! In my past life when I was bending wrenches, we had a guy switch the mags to "off" during a runup. The key stuck in "off" for a few seconds, and he finally got it switched back on, resulting in a heck of a bang! It was funny in the aftermath, especially because it was not me that did it!
 
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