Magneto check AFTER landing

gitmo234

gitmo234

Line Up and Wait
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gitmo234
Who does them, who doesnt? It's not called for in my manual but when i was out in colorado a CFI there mentioned to ALWAYS do it.

I used to have rough mags a lot on run up prior to take off, but I usually flew low and full rich. Lately I've been a lot higher and leaning on the ground and air a lot more, regardless of altitude.

Rough mags on run up for take off are more rare now. I've check my mags a few times prior to shut down and it seems more often now that it starts running rough on the right magneto with a drop that is still within limitations.

I'll lean it out and run it a bit, it will still be there. Hop in the next day to fly, start it up, do a run up, and it will be fine
 
The only mag check I do after landing is the momentary "off" check before shutdown to see if they'll actually ground out.

Also, remember, you can't hurt the engine by leaning too much on the ground during normal operations and taxi. Lean it until she coughs and just go barely rich from there.
 
okay so momentary "off check" is ringing a bell. Brings back he may have had me turn them of vs the same check as prior to take off. What is the effect when switching them off?

I'm leaning a lot more now. Flew from NJ to Maryland today near the last few remaining cloud cells and it was a bit rough, so I kept the mixture a bit rich.
 
It's a good idea to do a mag check at the end of the day. Or as one old guy put it, " you don't want to put a sick horse to bed."

It's a lot better to find out you need an A&P today before you come out the next morning or next week and find it out. Especially on trips it could save some time and aggravation.

I lean so aggresive on the ground that there's no way to take off full power and not know it. You cannot hurt these engines by over-leaning them on the ground. Immediately after start up I lean it as hard as I can.
 
gitmo234 said:
Who does them, who doesnt? It's not called for in my manual but when i was out in colorado a CFI there mentioned to ALWAYS do it.

I used to have rough mags a lot on run up prior to take off, but I usually flew low and full rich. Lately I've been a lot higher and leaning on the ground and air a lot more, regardless of altitude.

Rough mags on run up for take off are more rare now. I've check my mags a few times prior to shut down and it seems more often now that it starts running rough on the right magneto with a drop that is still within limitations.

I'll lean it out and run it a bit, it will still be there. Hop in the next day to fly, start it up, do a run up, and it will be fine
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I do. When I pull into the parking spot, (I am already as lean as it will run from the time I get off the runway) at idle speed I cut both mags momentarily, listen for the cut out, flip them both back on, throttle up to 1200 and pull ICO. All I am doing is a "mags cold" check.
 
I recently learned about the "off" check to make sure it grounds out so it doesnt accidentally get a "hand prop" start. It's on the checklist where I rent airplanes now. The airplane I used to own was a little prone to fouling plugs. I never did a full mag check after landing but as much as possible if stuff behind getting blown around wasn't an issue, I would run it up to 1500 rpm for about 30 seconds while "ground leaned." If a plug was fouled I could detect it without a full mag check. Then I'd bring the throttle and mixture all the way out together to shut down.
 
Getting to know my plane is a lot of fun. I dont mean that sarcastically either.

I'm not sure why I would never lean on the ground until recently. I was impatient with it and would pull to lean and it would pull out an inch or two then suddenly cut. I started paying more attention being easy on it and I notice the RPM raise, etc. It's definitely helped out a lot. When I dont lean the Right mag seems to always be rough. I've had to run it for 3 or 4 minutes before at high rpm to clear it up.
 
I discovered a failed mag once by doing an idle mag check....did not show at regular rpms. The internal distributor cap was burnt from arcing, as was the distributor gear, and the coil brush....
 
I do it as a post flight mag check to catch new problems early, and also to make sure they're grounded out for safety.
 
If you have a Bendix mag switch (very common in older airplanes) you could also do the AD-mandated check that so often is ignored or missed during annuals. Go to the off position at idle and force the switch up against the Off stop and see if the engine continues to run. There were many switches with a manufacturing flaw that ungrounded one mag in that position, and an old switch can get worn or sticky enough that you have a hot mag and not know it. I have found a half-dozen such switches in the last two years, one just the other day.

http://www.airweb.faa.gov/Regulator...C14960A415D956BD86256E520053A53E?OpenDocument

Dan
 
Some folks do the dead cut, or whatever one calls it, where the make sure they don't have a hot mag. Personally I don't get much value switching mags to off then back on, a right and left check does 95% of the same thing, I also don't check the mags after shutdown, just on the daily run up.

On the subject of mags, it's not a race, I've flown with folks who just race through their mag check, it's best to let the engine sit on on mag for a little bit, let her settle, really listen, look at your engine analyzer if you have one.
 
found an ungrounded mag on my off test just this week; fix ordered (new filter)
 
James331 said:
Some folks do the dead cut, or whatever one calls it, where the make sure they don't have a hot mag. Personally I don't get much value switching mags to off then back on, a right and left check does 95% of the same thing, I also don't check the mags after shutdown, just on the daily run up.

On the subject of mags, it's not a race, I've flown with folks who just race through their mag check, it's best to let the engine sit on on mag for a little bit, let her settle, really listen, look at your engine analyzer if you have one.
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Not much, if any, drop was noticed at idle on one mag in my 310.
 
I don't do one post-landing but rather airborne at descent power (20 in, 2300 rpm) about five minutes before landing. This practice is strongly recommended at the Advanced Pilot Seminars aka the GAMI folks. The idea is to identify a weak or bad mag so you can get it fixed before you taxi out for your next takeoff.
Jon
 
gitmo234 said:
I'm not sure why I would never lean on the ground until recently. I was impatient with it and would pull to lean and it would pull out an inch or two then suddenly cut.
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What year is your airplane?

Some of the mixture controls on early Cessnas (late 40s- 50s) were not as fine as the newer ones and it can be more difficult to really lean it out in the ground without the engine dying. My 170 was like that.
 
You know how it is - things work great until they don't, then they don't. A post-flight mag check will tell you if a mag has gone wonky while you were in the air, and help you get it fixed before missing a trip. I missed one, once, because of a bad mag - could have avoided that if I had checked it at the end of the prior trip (ten days or so earlier).
 
Fearless Tower said:
What year is your airplane?

Some of the mixture controls on early Cessnas (late 40s- 50s) were not as fine as the newer ones and it can be more difficult to really lean it out in the ground without the engine dying. My 170 was like that.
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its a 56. I think around # 780(ish) off the line of the first 172s. You can pull the mixture control an inch or more with very little change, then it suddenly gets very sensitive... RPM crease that's barely noticeable then a sudden death of the engine. As a newer pilot I was apprehensive of leaning mid-flight knowing its so easy to kill it. I actually do a lot of flying so as my confidence grows and I figure things out a bit more, it gets easier. I now lean a LOT
 
gitmo234 said:
its a 56. I think around # 780(ish) off the line of the first 172s. You can pull the mixture control an inch or more with very little change, then it suddenly gets very sensitive... RPM crease that's barely noticeable then a sudden death of the engine.
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Yup. Same thing I had on the 170.
 
I did notice a huge difference in my flight back from Newport news last friday. Climbed to 5500' just over the clouds and leaned. Sounded and felt like a different engine. Flight time was almost 30 minutes more (heading north) but I used probably 1/4 to half a tank less fuel
 
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