Backfire/afterfire

[gwav8or]

So, I was headed out yesterday to try and finish up an IPC.  During runup mag check, I accidentally switched the mags to off.  When I did, I instinctively switched the mag switch back to the right mag.  I know, not the best thing to do but I did it before I could even think about it.  Well of course as soon as I switched the mags back on there was a loud backfire or as some call it afterfire.  As I understand it, while the mags were in the off position the prop/engine still turning, some unburned fuel/air mixture was pushed out the exhaust valve and then ignited as soon as the mags were turned back on and spark provided to the plugs.

So now that everybody knows I'm a moron, what should I look at, have my mechanic look at or what should I look out for?  I think the most probable issue could be damaged valves or damaged exhaust?  What else?  What to do?

[Hank]

Look up the muffler, see if you blew off a flame tube

[gwav8or]

9 minutes ago, Hank said:

Look up the muffler, see if you blew off a flame tube

I will do that.  Thanks.

[EricJ]

Inspect the muffler for cracks.   You really just don't want a crack that'll send CO into the cabin when you turn the heater on.

 

[Vance Harral]

The mistake you made is common.  I've experienced it dozens of times, mostly teaching new student pilots to do a mag check.  I do try to avoid it, and I'm not saying it's no big deal.  But it's also very likely that nothing was damaged.  Certainly take a look - maybe at the next oil change - but I wouldn't lie awake at night worrying about damage to the airplane or to your ego.

[Shadrach]

6 hours ago, gwav8or said:

So, I was headed out yesterday to try and finish up an IPC.  During runup mag check, I accidentally switched the mags to off.  When I did, I instinctively switched the mag switch back to the right mag.  I know, not the best thing to do but I did it before I could even think about it.  Well of course as soon as I switched the mags back on there was a loud backfire or as some call it afterfire.  As I understand it, while the mags were in the off position the prop/engine still turning, some unburned fuel/air mixture was pushed out the exhaust valve and then ignited as soon as the mags were turned back on and spark provided to the plugs.

So now that everybody knows I'm a moron, what should I look at, have my mechanic look at or what should I look out for?  I think the most probable issue could be damaged valves or damaged exhaust?  What else?  What to do?

It happened to me many, many years ago after getting questionable instruction from my IA on how to test the Bendix switch. We had installed the new muffler the day before. It had about 10 mins in service before I tried to turn it into a giant firecracker. No damage but it sounded terrible.

[Yetti]

Happens.  Generally no damage.  You have a CO detector right?

[BDPetersen]

So, you’re human. I used to instruct students that if they did that or happen onto a dead mag to first close the throttle and let the engine wind down before moving the mag switch. Of course I knew they probably wouldn’t, but not a bad idea to have that thought as a self-briefing before each mag check.

[gwav8or]

20 hours ago, Vance Harral said:

The mistake you made is common.  I've experienced it dozens of times, mostly teaching new student pilots to do a mag check.  I do try to avoid it, and I'm not saying it's no big deal.  But it's also very likely that nothing was damaged.  Certainly take a look - maybe at the next oil change - but I wouldn't lie awake at night worrying about damage to the airplane or to your ego.

Thank you for the encouragement.

[gwav8or]

17 hours ago, Shadrach said:

It happened to me many, many years ago after getting questionable instruction from my IA on how to test the Bendix switch. We had installed the new muffler the day before. It had about 10 mins in service before I tried to turn it into a giant firecracker. No damage but it sounded terrible.

Yeah,  my exhaust is about a year old so really hoping I didn't do much damage.

[gwav8or]

16 hours ago, Yetti said:

Happens.  Generally no damage.  You have a CO detector right?

I sure do.

[gwav8or]

15 hours ago, BDPetersen said:

So, you’re human. I used to instruct students that if they did that or happen onto a dead mag to first close the throttle and let the engine wind down before moving the mag switch. Of course I knew they probably wouldn’t, but not a bad idea to have that thought as a self-briefing before each mag check.

Great idea, I'm adding that to my runup thought process.  Thanks.