how to learn about run up/engine concerns?

Badger

Badger

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Is there a good source for information about run up issues? Perhaps a good web site, or book?
I've heard about the Advanced Pilot Seminars web site and I will be browsing there.

for example: if I do a run up and switch a mag off and feel a rough running cylinder and see a drop in temp; what is my next step? (this thread isn't meant to diagnose a specific problem but rather look for information sources) What is the proper technique to try and burn off any carbon deposit? Any clues to determine if this is a fouled plug, sensor bad, mag, top plug, bottom plug, etc. What is a No fly issue vs a "fly her home and see AP" issue?

CFI's are commonly available to help with flight skills, but I have found AP mechanics to be less than helpful with engine problems. Typically I get "bring it over and we'll check it out." I understand they have liability, insurance and economic concerns.
 
I go to 2000+ on the RPM and lean it out like crazy for a minute or two. Then do it (mag check) again. If I still have an issue, out comes the spark plug socket and torque wrench to check the plugs. From there it becomes a flow chart process to determine the issue.
 
Rough mag during runup:

Try to clear it like EdFred said.

If still a problem then I will let the engine run at 1700 on the rough mag for a minute or so and start checking all the exhaust temps on the engine monitor. If one is clearly much cooler I note which cylinder it is.

Then I head back to the hangar, pull the cowl and trace the wires from the noted cylinder back to the mags to determine which plug in that cylinder is fired by the mag that was rough.

Takes longer to R&R my cowl than to locate and solve a shorted spark plug issue.
 
so are you guys keeping a few extra plugs in your hangar, and cleaning checking gap when rough plug happens? In other words is a rough cylinder during run up a non AP issue if you can replace plug followed by a normal run up? Thus determine it is not the mag.
 
If you can demonstrate cleaning, inspecting gapping plugs, I don't see an issue. If a plug is shorted it should be very obvious when you pull it and look at it.

Engine monitor took me right to the problem.

 
Badger said:
Is there a good source for information about run up issues? Perhaps a good web site, or book?
I've heard about the Advanced Pilot Seminars web site and I will be browsing there.

for example: if I do a run up and switch a mag off and feel a rough running cylinder and see a drop in temp; what is my next step? (this thread isn't meant to diagnose a specific problem but rather look for information sources) What is the proper technique to try and burn off any carbon deposit? Any clues to determine if this is a fouled plug, sensor bad, mag, top plug, bottom plug, etc. What is a No fly issue vs a "fly her home and see AP" issue?

CFI's are commonly available to help with flight skills, but I have found AP mechanics to be less than helpful with engine problems. Typically I get "bring it over and we'll check it out." I understand they have liability, insurance and economic concerns.
Click to expand...

In a nutshell: We may have an idea but there is no computerized analyzer connection like you have in your car. We may have to do a bit of exploring to find the cause.
 
EdFred said:
I go to 2000+ on the RPM and lean it out like crazy for a minute or two. Then do it (mag check) again. If I still have an issue, out comes the spark plug socket and torque wrench to check the plugs. From there it becomes a flow chart process to determine the issue.
Click to expand...
:yeahthat: That's what I've always done. If it doesn't clear and still runs rough, then it's more of an issue than you can fix and needs to see a mechanic.
 
EdFred said:
I go to 2000+ on the RPM and lean it out like crazy for a minute or two. Then do it (mag check) again. If I still have an issue, out comes the spark plug socket and torque wrench to check the plugs. From there it becomes a flow chart process to determine the issue.
Click to expand...

This is the technique in my POH
 
Badger said:
In other words is a rough cylinder during run up a non AP issue if you can replace plug followed by a normal run up? Thus determine it is not the mag.
Click to expand...
Depends whether you document the discrepancy, or not. If you document the rough running engine, it is beyond the limitations of "Preventive Maintenance"
 
I did not see it mentioned so I will mention it.

With my Lycoming IO-320 with Bendix Magnetos it is important to lean for taxi always.

If I forget to lean for taxi it is not unusual to foul a plug.

They will usually clean out if I run her up to 2000 and lean till she runs rough.

I keep two spark plugs and a spark plug wrench in the aircraft in case that doesn’t work out.

Plugs seem to last around 300 hours before I need to clean them and 1,000 hours before I need to replace them.
 
Install REM37BY plugs in any engine that qualifies for them. They are really foul-resistant.

Small Continentals will oil-foul their plugs when warming up. The lower plugs are really low in the head, and oil getting past the cold piston and rings will end up in the plug, shorting it. Got to get the RPM up and lean it and it will burn out of there.
 
EdFred said:
I go to 2000+ on the RPM and lean it out like crazy for a minute or two. Then do it (mag check) again. If I still have an issue, out comes the spark plug socket and torque wrench to check the plugs. From there it becomes a flow chart process to determine the issue.
Click to expand...

So, after this 2000 burn off, you return to 1700 for the mag check or do it while at 2000rpm?
 
GlennAB1 said:
Depends whether you document the discrepancy, or not. If you document the rough running engine, it is beyond the limitations of "Preventive Maintenance"
Click to expand...
That's not true, otherwise you can throw away all the items in FAR 43-A owners are allowed to clean / replace spark plugs and return it to service on their pilots number.
 
Badger said:
So, after this 2000 burn off, you return to 1700 for the mag check or do it while at 2000rpm?
Click to expand...
Doesn't matter, it runs right or not. You can do the mag check at any RPM. because the mag works at all RPM.
 
Tom-D said:
That's not true, otherwise you can throw away all the items in FAR 43-A owners are allowed to clean / replace spark plugs and return it to service on their pilots number.
Click to expand...
You've missed the point. 43-A is very clear what it allows and doesnt. It doesn't authorize the pilot owner to troubleshoot/repair a rough running engine.
 
GlennAB1 said:
You've missed the point. 43-A is very clear what it allows and doesnt. It doesn't authorize the pilot owner to troubleshoot/repair a rough running engine.
Click to expand...
common sense does tell us what/when. why would the FAA allow pilots to do anything if they were not allowed to decide what and when.
 
Badger said:
CFI's are commonly available to help with flight skills, but I have found AP mechanics to be less than helpful with engine problems. Typically I get "bring it over and we'll check it out." I understand they have liability, insurance and economic concerns.
Click to expand...

For starters, there are a scant few CFIs that I would listen to when it comes to suggestions on how to run an engine. The ones I would listen to are usually mechanics as well (but I wouldn't listen to all of them either). Additionally, the reason you probably get the responses you're getting from mechanics is because of the how the question is being posed and the perceived problem. Many problems can be caused by multiple things, so there isn't a method for being able to tell you exactly what is wrong without looking at it.

My suggestion would be to not focus on aircraft engines specifically, but read and understand how the typical four cycle engine actually works. If you know how an engine is actually supposed to work you can analyze and troubleshoot things much more effectively. Even many certified mechanics are lacking in this department.

Badger said:
so are you guys keeping a few extra plugs in your hangar, and cleaning checking gap when rough plug happens? In other words is a rough cylinder during run up a non AP issue if you can replace plug followed by a normal run up? Thus determine it is not the mag.
Click to expand...

Why would you leave them in the hangar? They should be in the airplane, with you, ready to use. Or do all your plugs foul at your home base? ;)
 
GlennAB1 said:
Depends whether you document the discrepancy, or not. If you document the rough running engine, it is beyond the limitations of "Preventive Maintenance"
Click to expand...
document? where? this is not a 121 operation, where every squawk is put in the aircraft log book. i do not write squawks in my log books. I put the maintenance performed in them.
bob
 
Badger said:
So, after this 2000 burn off, you return to 1700 for the mag check or do it while at 2000rpm?
Click to expand...
After it sits leaned out at 2000, bring the power back to 17 and then go mix full rich and re-try the runup. Like Tom says the RPM used at this point doesn't really matter but I always bring it back to the checklist recommendation.
 
GlennAB1 said:
You've missed the point. 43-A is very clear what it allows and doesnt. It doesn't authorize the pilot owner to troubleshoot/repair a rough running engine.
Click to expand...

I'll keep that in mind if it ever happens that I need to while in flight. LOL. Oh no... I'm not authorized!
 
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