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If I'm flying along at about 50mph (85% throttle) and my engine is running at 2000RPM. Is it a good idea to put the carb heat on because I am no longer using full power? Also. What if I'm flying at around 5000ft ASL?

I'm a bit curious as to what happened to my engine as I was taking everything nice and easy and after 10 hours my engine has gone from excellent to good. My thought is that with some carb icing my engine got slight damage. Am I right or wrong?

Mark

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Intel Core i7 3770K | 16GB DDR3 1600 | Nvidia GTX470 | 24" LCD Monitor | 2 x 1TB HDD, 1 x 500GB HDD | Windows 7 Profession 64 bit

Normally anything below 2000rpm you should apply carb heat because of less fuel going through.

Carb heat is normally only used during descents and/or whenever you have rpm less than 2000.

Engine damage can happen when you have excessive use of carb heat during taxiing/ground manuevers. Often you are overheating the engine on the ground since there's less relative air to hit the engine (it cools in flight)...and applying carb heat on the ground just makes it worse. Carb heat also can suck up rocks/pebbels, dirt, sand, etc when you're on the ground--very bad for engines. This is why it's important to shut off carb heat after you land...but don't do it until you're OFF the runway. Lots of pilots try to do too many things at once when they are on the ground and end up getting ahead of themselves and ground looping the airplane.

Do you have your engine times set to overhaul at 300 or 1800? Maybe if you have it set to 300 it may already be wearing out? FYI, 1800 is the manufacturer's real time before overhaul....but that's just a recommended overhaul time. Many times these engines don't actually sputter or show any signs of major "wear and tear" until 3000 hrs! Very very reliable engines...probably still the best out there despite modern technological advances.

(Skunker, we double posted.)


Here are some things that can cause an engine to become damaged pre-maturely. You may have been experiencing one of more of these:

- Check oil temps when you start flying.
Sometimes you start the engine and just takeoff. While an automobile engine can withstand this kind of abuse, aircraft engines are more sensitive with their tolerances. Running high power on a cold engine over and over will cause pre-mature wear.

- Negative G aerobatics.
Doing a simple aileron roll in a cub can cause prolonged negative G's. Think of the engine oil system. It has an oil sump on the bottom where the oil collects and is sucked in and pushed through the engine. At any given point when the engine is running, you may have 3 quarts on the bottom and 1 quart circulating throughout the engine. If you are running 1 quart down (3 quarts), you will not have 2 quarts on the bottom with 1 quart circulating, 2 quarts down you only have 1 quart in the bottom, etc. If you are saving your flights, you need to check your oil before you takeoff.

OK, now take a running engine and turn it upside down. All of the oil is now rushing to the top, and the oil sump pumping air, and your oil pressure is abruptly cut off as your sump is pumping air. Now, an engine can endure 0 oil pressure time and time again, but if you are applying full power, are upside down, and have no oil pressure, your engine parts are now making metal on metal contact under full stress. If you perform a lot or aerobatics and endure zero oil pressure, this will accelerate engine wear. If you are in the habit of leaving your throttle and just throwing the cub all over the place, over time, little by little, your engine will suffer.

Fortunately, you have an oil pressure gauge. Watch it and you will see. Pulling back the throttle under negative g forces is something many pilots practice for the reason of preserving engine life.

- Prop overspeed.
This can happen so easily. You MUST pull back that throttle any time your airspeed is exceeding 100mph or so. One really long high speed dive, and your engine can be at 2800RPM or even more. You can experience slight damage, or possibly severe damage. It is when you stress an engine to this point when things break, so be careful.


Scott.

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A2A Simulations Inc.

I thought I was. I'll double check that the oil is getting warm enough.
Nope. Not doing them....yet!
In the 2D Panel (shift+4) it always shows that I have 4 brown coloured boxes, even after a 2 1/2 hour flight, so I'm assuming it's still full. Nothing happens when I press Refill anyway.
I guess this could be the most likely cause. Although I set the engine to idle and try not to descend too quickly so that the prop won't overspeed.

Fortunately it's a simulator so it costs nothing to fix so it isn't all bad. But I really am trying to do it right. Practice will get me there in the end. I hope.

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Intel Core i7 3770K | 16GB DDR3 1600 | Nvidia GTX470 | 24" LCD Monitor | 2 x 1TB HDD, 1 x 500GB HDD | Windows 7 Profession 64 bit