Cotton AeroVee 0795

[Bryan Cotton]

Edit: On further consideration, I think this is exactly what your EGT test is telling you. If you're running on 2 cylinders only, the exhaust gasses are still going to make their way through the pipes and warm the other "cold" EGT thermocouples to a lesser extent.

I would expect the dead cylinder would be pumping cold air past the EGT in its exhaust pipe. How is the other cylinder going to pump hot air backwards through the pipe and into the engine?

[Area 51%]

Edit: On further consideration, I think this is exactly what your EGT test is telling you. If you're running on 2 cylinders only, the exhaust gasses are still going to make their way through the pipes and warm the other "cold" EGT thermocouples to a lesser extent.

I would expect the dead cylinder would be pumping cold air past the EGT in its exhaust pipe. How is the other cylinder going to pump hot air backwards through the pipe and into the engine?

It would be interesting to have an EGT on the exit pipe of my air compressor. No combustion there either, but the pipe is too hot to keep your hand on.

[Bryan Cotton]

It would be interesting to have an EGT on the exit pipe of my air compressor. No combustion there either, but the pipe is too hot to keep your hand on.

Interesting point. I would suspect the heat of compression is much less than the heat of combustion.

[GraemeSmith]

Sidenote: I was taught in my early flight school days to always do a mag check just prior to every engine shutdown. A quick flip of all ignition switches OFF/ON at idle before killing the engine with mixture/fuel shutoff. I'm curious if this is standard practice for others (I believe it should be.)

A rare flight school. Most don't want you doing this. If you don't get it JUST right and get a fuel air charge pass through the cylinder and exhaust valve into the muffler - as the mags go hot again and the engine runs - the next exhaust cycle will ignite the charge in the muffler with a "pop" and you can blow the muffler off. Even if it's new and takes the hit - it stresses it and shortens the life.

Rookie students rarely have the finesse to do it right. So it's banned.

--

But it's a very legitimate test if you can do it right and just "blip" it a fraction to check the mags are grounding.

Like I did just after flying on Tuesday and lo and behold - I have a hot mag........

If it's not one thing..... :-)

[Bryan Cotton]

I was taught to check for a hot mag. I do it occasionally. Never blew up a muffler. Not much worry on a Sonex.

As a teenager, I was stuck behind a large truck on a large hill once in my '71 Olds Cutlass. Finally got a pass zone after cresting the hill. Went wide open, and passed the truck. Took my foot off the gas and it got stuck wide open. My first thought as I passed 90 MPH was to turn off the ignition. Then did some troubleshooting and discovered the floor mat had jammed the pedal. Ignition back on. That muffler blew in a spectacular fashion.

If it's not one thing..... :-)

Here's hoping for you that it's the top mag!

[Rynoth]

Sidenote: I was taught in my early flight school days to always do a mag check just prior to every engine shutdown. A quick flip of all ignition switches OFF/ON at idle before killing the engine with mixture/fuel shutoff. I'm curious if this is standard practice for others (I believe it should be.)

A rare flight school. Most don't want you doing this. If you don't get it JUST right and get a fuel air charge pass through the cylinder and exhaust valve into the muffler - as the mags go hot again and the engine runs - the next exhaust cycle will ignite the charge in the muffler with a "pop" and you can blow the muffler off. Even if it's new and takes the hit - it stresses it and shortens the life.

Rookie students rarely have the finesse to do it right. So it's banned.

--

But it's a very legitimate test if you can do it right and just "blip" it a fraction to check the mags are grounding.

Like I did just after flying on Tuesday and lo and behold - I have a hot mag........

If it's not one thing..... :-)

Indeed, throttle should be fully idle (as closed as possible) and the "blip" should be as short as possible. I've never experienced a backfire in all my years though (granted I also have never flown an aircraft with a muffler.)

FWIW the flight school was Embry-Riddle Aeronautical University, not a small operation by any means.

The real trick in many aircraft is not letting the key get jammed when you go to "off" on the mags, since that's also typically the key removal position.

Example of my mag shutdown check at 14:13 in my First Flight video:

https://youtu.be/D8Z_OK6SFh8?t=849

[Bryan Cotton]

New magnatron installed, P lead works now. Issue closed.

A better idea than the blip: just let it shut off and air out.

[flyingbear]

Why cant you shut off the mags>>? Defective? Mine were but Sonex knew it and made me pay for new ones.

[Bryan Cotton]

Why cant you shut off the mags>>? Defective? Mine were but Sonex knew it and made me pay for new ones.

I had one defective mag. I am the original buyer and mine was replaced for free after I provided enough evidence that the mag was bad.

[Bryan Cotton]

I've redone my sump. I got acorn nuts and drilled them for safety wire.