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Challenged

Challenged

Pattern Altitude
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Challenged
Was on a cross country on Friday with a friend and was about an hour away from my home airport when I heard the heart dropping sound of my engine starting to stutter. I immediately pulled the carb heat and pushed the mixture in, but the engine stopped. Reached over to the GPS and pushed the "Nearest" button and quickly turned the plane in the direction of the closest airport.

I actually was able to get the engine somewhat going again after setting up for best glide, but it was extremely rough running and not really producing much power. I called ATC and told them I was deviating to the nearby airport and felt that I could glide and land without issue. The controller told me to just call him once we landed. Very luckily, we were cruising at 7,500 feet and the random airport we happened to be flying by was maybe 4 miles away.

I have to say my landing wasn't the best ever, but I've also had worse even with normal engine power. Anyhow, the runway was long and I came in with a fast slip and set it down without much issue.

The problem turned out to be plug fouling (but I'm guessing a bit of carb ice was involved as well). I had the plugs all cleaned and completed the rest of the cross-country (about 11 hours of flight time) without issue.

I kind of thought that I would experience an engine failure one day, but I really didn't think it would happen to me while I am still such a low timer (just made it past 100 hours). Anyhow, just thought I would share my tale..always nice when they have a happy ending.
 
Yay, one for the good guys. Nice going.
the plugs...think it could have been too rich?
 
Good job.
I always lean religiously but perhaps I should learn how to use GPS. I do the thumb on sectional technique.
 
Nice work! Always glad to hear a story that doesnt involve injury or bent metal.



Just curious, do you own or rent the airplane?

If I understand spark plugs correctly, A spark plug is fouled when it contains carbon deposits due to not being able to burn off excess fuel, consequence of running too rich. Not that adding carb heat during an engine failure is a bad idea, but adding carb heat will actually make your mixture even more rich (less air due to decreased density, with the same amount of fuel) potentially adding to the problem of a fouled plug.

An attempt at clearing the spark plug on the ground may be done by running at ~2000 RPM at a nice lean mixture for about 30 seconds. If that doesn't make the engine run smoother after, definitely need to get it looked at.


With the fear of fouled plugs, its always a good idea to lean your mixture during taxi and not to forget to properly lean at your cruising altitude. (shouldnt really be leaning during a full power climb, extra fuel aides in cooling, and leaning during a high power operation can cause temperatures to get too high)
 
Good work!

I have to ask - Did you do a runup at the beginning of that particular leg? Notice anything unusual? I ask because there was a time where I would do a runup for the first leg of the day and generally skip it after that. Now, I generally do a runup for every leg. I didn't have a failure or anything to prompt it, but I think after a few discussions here I decided to err on the side of caution.

The good news is, because of the law of averages, you'll never experience another engine failure. ;) (oh, if only that were true!)

Please let us know what they find out the cause was!
 
To answer the question above, the plane is mine; I've owned it for about 5 months.

I generally lean the plane on the ground, then run rich for my run-up and then keep it rich for the full power climb to cruise altitude. After that, I'll pull the power back to cruise RPM and then start leaning.

In the past few months I've done a lot of lower level flying...pattern work, VFR maneuvers and such, I haven't been leaning much at these lower altitudes. After experiencing this incident, I may change my habits on that (or at least have my plugs checked more often). The mechanics said the plugs were some of the worst they had seen. I believe the POH indicates leaning above 3000 feet, but would be curious to know what you guys all do in that regard.

My original run-up before starting the trip was fine, but the mag check on the ground after this incident showed extreme RPM drop, so that's how the mechanics knew to start with the plugs.
 
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Challenged said:
I believe the POH indicates leaning above 3000 feet, but would be curious to know what you guys all do in that regard.
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Don't lean at an altitude. Lean at a power setting. 65% power and below, lean the cra* out of it.

You will have to consult the POH tables and become familiar with the rpms and altitudes which produce 65% and below.

Altitude is an important factor used for power setting, as the lower pressure at higher altitude effectively lowers the maximum power available. But if you are dinking around at 2500 feet at low power, go ahead and lean!

If you have an EGT, note where the gauge is when on full power, full rich climbout from a low altitude airport. Use this as your red line EGT. Do not exceed when leaning.

Finally, your plugs were in bad shape. How old are they? They cannot be cleaned up and re-used in perpetuity. I have no experience to back this up, but it seems that plugs with eroded electrodes, no matter how clean at the start of an engine run, are likely to foul quickly.

-Skip
 
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Great information, thanks. Generally I'd say my leaning technique is pretty good, but probably not aggressive enough based on this event.

That said, and just to play devil's advocate, if you were taking off and doing say 5 touch and gos in the pattern at an airport at sea level, would you lean the mixture at all?
 
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Challenged said:
Great information, thanks. Generally I'd say my leaning technique is pretty good, but probably not aggressive enough.

That said, and just to play devil's advocate, if you were taking off and doing say 5 touch and gos in the pattern at an airport at sea level, would you lean the mixture at all?
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I never did as a student at KBDR, altitude 10' msl. The Archer I trained in never had plug fouling problems. Then again I do not know how often they changed the plugs, so were they new or not??? :dunno:

-Skip
 
Superb result. You're ok and you can use the plane again great landing!!!
 
Challenged said:
Great information, thanks. Generally I'd say my leaning technique is pretty good, but probably not aggressive enough based on this event.

That said, and just to play devil's advocate, if you were taking off and doing say 5 touch and gos in the pattern at an airport at sea level, would you lean the mixture at all?
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To answer your question, I trained at airports almost at sea level and I didn't lean doing T&G in the pattern. Take-off should be done at full power, I usually get to altitude just before turning downwind and I'm only flying for less than a minute before starting my descent. I would be at rich for landing- not much time to lean out the engine before going down again. Leaning, in this situation, is just one more thing to do when you are already fairly busy, in a high-traffic area where you need to be looking around.
 
Challenged said:
To answer the question above, the plane is mine; I've owned it for about 5 months.
Click to expand...

Welcome to ownership. ;)

I generally lean the plane on the ground, then run rich for my run-up and then keep it rich for the full power climb to cruise altitude. After that, I'll pull the power back to cruise RPM and then start leaning.

Generally I'd say my leaning technique is pretty good, but probably not aggressive enough based on this event.
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Where it should be is lean enough that if you push the throttle in, the engine will cough and not develop more power. I try to put it in a spot where, say I'm at 1000 RPM, if I push the throttle in it'll momentarily surge to about 1300 RPM while coughing, sputtering, wheezing, and coming back down to 1000 until I either push in the mixture or pull the throttle.

Do you happen to have an engine monitor? If not, it's a good investment. If you learn how to use it properly, you can sometimes see an issue like this before you otherwise would (which can save your bacon when you're NOT at 7500 feet and 4 miles from an airport), you can usually tell the mechanics exactly where the issue is ("I need you to replace the bottom plug on the #4 cylinder" instead of "my engine runs rough") and save money on maintenance, plus you can lean much more accurately and probably save money on fuel as well.

In the past few months I've done a lot of lower level flying...pattern work, VFR maneuvers and such, I haven't been leaning much at these lower altitudes. After experiencing this incident, I may change my habits on that
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Lean for cruise regardless of altitude. You'll burn a lot less fuel this way, too. The DA40 that I'm flying burns 18gph on a full-rich climbout, and only half that in cruise. Even a high-power, low-altitude cruise at 2500 MSL and extra-rich to keep CHT's down is only 10.5 gph. Up until less than 2 years ago, I didn't fly anything with an engine monitor. In 2009, we had a JPI EDM 700 with fuel flow added to the 182, and in late 2010 we bought the DA40 with the G1000 which has a built-in engine monitor as well. Now I'm spoiled and wouldn't want to fly without them!
 
1) ALWAYS follow the POH checklist for a rough running engine

2) The application of carb heat enrichens the mixture (less air, same fuel) so the movement of the red lever to full rich will further enrichen it. Just food-for-thought as you could go over-rich and possibly have problems there deppending on your DA at the time.
 
dillardrg said:
Good job handling the emergency.

Check out Lycoming Service Letter SL 185B for Lycoming reccomended leaning procedures.

http://www.lycoming.textron.com/support/publications/service-letters/pdfs/SL185B.pdf
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That specific operation considerations for engines that were rated for 80/87 now using 100LL. The OP didn't mention whether his engine fell into that category, and I don't know what he flies.

Service Instruction 1094D has recommended leaning procedures:

http://www.lycoming.textron.com/support/publications/service-instructions/pdfs/SI1094D.pdf

However it is worth noting that you should look at your POH for additional information.

Regarding fouled plugs: I have had a number foul on me, they are annoying. If it happens again soon, you should consider replacing your spark plugs or seeing if you have a weak mag. For a while, the 310 was fowling a plug every flight. One new set of plugs later, no problems. And I run it pretty lean - it was not a mixture issue.

It sounds like your technique was good and you handled the situation well. You did well by following the standard POH procedure of pull carb heat and enrichen the mixture as the first steps. One thought: you also indicated that made things worse, not better. Knowing now how your engine responds to a fouled plug (and the fact that at 7500 ft you were then running super rich by going full rich and pulling carb heat), if you felt you had some time and mental capacity left after establish best glide and identifying an airport or place to land at, you might want to consider seeing if you can change the mixture position to do better. If you know that one thing made it worse, then the reverse should at least take you back to your previous operating condition, and more fiddling might give you some other options (fuel tank, etc.). It is entirely possible that you may have been able to get the engine going again, although I certainly wouldn't blame you if you stopped for a change of underwear even if you did. :)
 
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