Can anyone PM me and explain to me what a rough running engine is? Is that a specific problem, or a general term for a wide array of engine troubles? Is it minor, serious, or does the severity vary depending on the nature of the problem?
Thanks!
Tamsin
Rough running engine
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It depends on who you hear it from. Rough running engine from a news reporter generally means "Not a clue what is going on but reporting it anyway".
Rough running from a pilot can mean anything from a funny noise to excess vibration to power surges to a swallowed valve. The engine is almost always still generating some kind of power.
Rough running from a pilot can mean anything from a funny noise to excess vibration to power surges to a swallowed valve. The engine is almost always still generating some kind of power.
A "rough running engine" usually means that one or more cylinders is NOT producing the thrust on the piston that it should, during the power stroke.
It may do this because one or more cylinders is having problems with:
1) the spark not firing as strong as it should, when it should, or
2) too much or too little fuel, or
3) too much or too little air, or
4) mechanical failure (eg damaged exhaust valve, damaged piston, etc).
Very fussy pilots will also complain of a "rough running engine" when there is some kind of imbalance in the prop or rotating assembly.
Most aircraft piston engines operate very slowly, with large clearances, and are very forgiving. If you feed them gas, don't plug up the intake, and keep a little oil in the crankcase, they will generally keep running.
It may do this because one or more cylinders is having problems with:
1) the spark not firing as strong as it should, when it should, or
2) too much or too little fuel, or
3) too much or too little air, or
4) mechanical failure (eg damaged exhaust valve, damaged piston, etc).
Very fussy pilots will also complain of a "rough running engine" when there is some kind of imbalance in the prop or rotating assembly.
Most aircraft piston engines operate very slowly, with large clearances, and are very forgiving. If you feed them gas, don't plug up the intake, and keep a little oil in the crankcase, they will generally keep running.
Just to add another common situation that would generally be called “rough running” is due to carburetor icing. Caused by in one of two things,
1. restricted airflow into the engine from ice blocking part of the carburetor & intake,
2. once the carb heat is selected ON after the ice is detected the engine will begin to slow, surge, pop and cough due to ingesting the melting ice.
Carburetor ice is likely the most common causes of a “rough running” aircraft engine. I would recommend reading more about it in ‘From the ground up’, asking a flight instructor or doing a search online.
1. restricted airflow into the engine from ice blocking part of the carburetor & intake,
2. once the carb heat is selected ON after the ice is detected the engine will begin to slow, surge, pop and cough due to ingesting the melting ice.
Carburetor ice is likely the most common causes of a “rough running” aircraft engine. I would recommend reading more about it in ‘From the ground up’, asking a flight instructor or doing a search online.
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This is sort of a rough running engine question, and I don't mean to hijack the thread. On my Multi-IFR test, the examiner said, "you hear a BANG off of the left engine, and you notice your manifold pressure is less" I think I said something like, "mixture rich, prop fine, throttle full, do I notice any difference?" etc. etc. I don't know how the @#$! I passed.
In the de-brief, he said carb ice could do this.
Anyone out there ever heard a bang, then notice a rough running engine/loss of power?
-istp
In the de-brief, he said carb ice could do this.
Anyone out there ever heard a bang, then notice a rough running engine/loss of power?
-istp
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bush pilot
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That's what I thought. But if I had carb ice, I'd notice it before there was a BANG. I would think. I've only had a bit of carb ice when I put on the heat, and noticed a couple of seconds of chug-chug, then it was cool.
This 250 hour Maverick would still like to know if carb ice can cut out a cylinder, and it doesn't recover.
-istp
This 250 hour Maverick would still like to know if carb ice can cut out a cylinder, and it doesn't recover.
-istp
Istp
I cant think of any reason why you would have a bang or anything that would cause just one cylinder to quit due to carb ice. In a twin I would think you would hear a frequency or yaw change before the ice problem got that far along. I’ve only had an engine lose a significant amount of power once in flight and that was due to a stuck valve (a typical problem on some continental engines). I cant count how many times I’ve had carb ice. As you said once you catch the development of ice and turn the heat on, a few chugs and a couple adjustments (mixture & heat) the ice probable wont be back.
Now that you have your multi… you should go back and ask that DFTE if he could explain just how carb ice would cause the situation he set up for you. Keep on questioning every situation you don’t understand it will save your ass someday.
PT
I cant think of any reason why you would have a bang or anything that would cause just one cylinder to quit due to carb ice. In a twin I would think you would hear a frequency or yaw change before the ice problem got that far along. I’ve only had an engine lose a significant amount of power once in flight and that was due to a stuck valve (a typical problem on some continental engines). I cant count how many times I’ve had carb ice. As you said once you catch the development of ice and turn the heat on, a few chugs and a couple adjustments (mixture & heat) the ice probable wont be back.
Now that you have your multi… you should go back and ask that DFTE if he could explain just how carb ice would cause the situation he set up for you. Keep on questioning every situation you don’t understand it will save your ass someday.
PT
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If carb ice is allowed to continue long enough, it could prevent fuel from being metered out. This would cause an immediate lean condition, detonation and the loud noise is a backfire through the intake/carb.
I've met a fellow that believes this happened to him on a Cessna 170 a couple years ago, and it damaged his cowling. (he had the carb heat on at the time, so the percussion of the backfire backed up through the heat muff)
I've met a fellow that believes this happened to him on a Cessna 170 a couple years ago, and it damaged his cowling. (he had the carb heat on at the time, so the percussion of the backfire backed up through the heat muff)
