How do you shut down?

[David Mazer]

I used to do a mag check by turning to off then back on but my IA advised that I just turn to left, then right mag and watch for and RPM drop, even at idle.  Seems to work great.

[jlunseth]

You don't turn it off for any length of time, just a very quick off then on. There is no backfire. You listen to hear if the engine momentarily stops firing (it should), and that is all there is to it. Going left then right is not always effective because the cylinders will all still fire and there may be no noticeable change in RPM's with the engine at idle.

[jetdriven]

I noticed a change in RPM at idle when switching from L to R, its not much, but noticeable. But that doesnt check if the magneto switch grounds both mags when switched to OFF, which is what the AD covers.  The Bendix (now TCM) magneto switch would unground the mags in the OFF position (the contacts would wear out) , which is what prompted the AD.

[jlunseth]

Ouch. 

 

I had a checkride recently and got an AD compliance report to get the plane ready for it.  I saw the AD but really didn't read it, just saw that it requires an ops check and sign off by an AP every hundred hours.  Mine was overdue so I got it done.  Didn't actually read the AD, although I knew it had to do with the switch not grounding the mags.  Guess I will be having it done regularly now.

[Skybrd]

I turn the accessories switches off, avionics switch off, set the rpm to 1000, turn off the master switch, pull mixture to cutoff, turn off ignition key, reset trim for next a flight, turn off fuel selector. I always leave cowl flaps open to release heat from the cowling and sometimes open the top Lopresti cowl flip up doors.

[DaV8or]

  On 12/2/2013 at 3:00 PM, Jamie said:

I'm not doubting either one of you guys about the mag check, I'll probably start doing it. But...

 

I seem to remember something from the far distant past about going to off and then back on being a serious no-no. Something about, I dunno.. it would hurt something. If this isn't it, what am I likely remembering?

 

All I know is, for 20+ years I've been very careful not to go to "OFF" during the mag check.

 

You're probably thinking of the caution not shut the mags off in cruise. In cruise, if you shut the mags down, but don't quickly pull the throttle closed, the cylinders continue to be fed fuel and the fuel will flow into the exhaust system. When you go to turn the mags back on, the condition is ripe for a big ol' back fire. Back fires can really wreck your exhaust system. Momentarily turning the mags off and then back on again at idle I doubt will hurt anything.

[DaV8or]

On shut down, I use the same technique whether it is at the end of the day, or a planned hot start. I taxi with it lean and leave it lean. I shut off the avionics master, then run it up to around 1400 rpm. Then I pull the mixture to cut off, followed by shut off lights, master and finally the ignition to off. I leave the throttle locked in that 1400 rpm position and don't touch it again until the motor is running again. When I go to restart, either hot or cold, she'll fire right up. Hot starts just take a few more blades than cold. Works every time.