Engine Failures

[C-150Pilot]

Did you ever have an engine failure during your career/training? What happened and what was the problem?

[gelbisch]

Yeah, my student, in the dead of winter, went carb heat cold THEN poured the coals to 'er coming out of a simulated forced approach--in spite of my having told him a billion times not to. Fortunately she started up okay after I pulled the carb heat again. No need for chastising... I think he learned his lesson that day! (And me too... watch students more closely!!)

[LostinRotation]

Souldn't the carb heat be hot during the entire forced approach procedure to eliminate the possibility of carb ice then, full power carb heat cold on the overshoot ? Leaving carb heat on robs you of power much needed on an overshoot, much required for two people in say a 150 in a landing configuration.


If you had the carb heat on and there was ice build up, wouldn't you notice the rough running engine long before the overshoot ?

-=0=LIR=0=-

[Phlyer]

I had a photo flight in the dead of winter one time - it was -35 on the ground and -50 at 10,000 plus wind chill. I leaned out the engines as usual and they both died. Follow the procedure - everything up and they fired up again right away.

[Doc]

Piston engines at -35....some people never learn? BTW, "wind chill" has no effect on metal...just flesh.

[Phlyer]

Exactly - the seal on the landing gear was gone so I got air coming in at 160 mph. Arctic boots and I still got frostbite.
BTW I said the same to my boss, but 'it had to be done'.

[cplanedriver]

Had the O-320 in my Citabria power down to no more than 1300 RPM over Northern Mb. Was on floats so no big deal but had to sit on a rock for 4 hours and the a/c was there for a week. Brought out the carb, checked the mags and then after $1000 I fixed it with a coat hanger and a poplar stick by cleaning out the burnt baffles from the mufler.
Had an O-470 in a 182 almost quit on an overshoot training a pilot for charter ops. Got minimal power, enought to limp around just over the trees to get level at about 150 feet and got back to the strip.They took all six jugs back to the engine builder with very low compression. 50 hours on a rebuild, go figure.
R 985, again 25 hours on a newbie engine, blew all its oil out on climb at 3500 over 3000 ft mountains, 6 miles from the coast. Managed a glide and dead stick to the water. Was alone, thank goodness, with the rush of the wind and the clank when she quit.
Donchya just love flyin ....Gary

[Right Seat Captain]

Souldn't the carb heat be hot during the entire forced approach procedure to eliminate the possibility of carb ice then, full power carb heat cold on the overshoot ? Leaving carb heat on robs you of power much needed on an overshoot, much required for two people in say a 150 in a landing configuration.


If you had the carb heat on and there was ice build up, wouldn't you notice the rough running engine long before the overshoot ?

-=0=LIR=0=-

From the sound of the story, he did have the carb heat on when he was doing the forced approach, otherwise he couldn't have put it cold. But anyways, I think the point was that the student did Carb Heat Cold THEN Full power, where it should be the other way around, especially in the winter.

[gelbisch]

Souldn't the carb heat be hot during the entire forced approach procedure to eliminate the possibility of carb ice then, full power carb heat cold on the overshoot ? Leaving carb heat on robs you of power much needed on an overshoot, much required for two people in say a 150 in a landing configuration.

If you had the carb heat on and there was ice build up, wouldn't you notice the rough running engine long before the overshoot ?

From the sound of the story, he did have the carb heat on when he was doing the forced approach, otherwise he couldn't have put it cold. But anyways, I think the point was that the student did Carb Heat Cold THEN Full power, where it should be the other way around, especially in the winter.

Couldn't have said it better myself.

[LostinRotation]

Not trying to be anal here but for my own educational purposes, what difference would 0.25 seconds make ? They are right beside each other.
If the carb heat was on the entire time it would be safe to say the venturi tube was clear of ice at the time of adding full power....not to mention a little warm, after 250 degree exhaust passing through it for the past two minutes. How could the venturi become blocked, or partly blocked in that short of time ?

I've checked through the entire P.O.H for a 1 fiddy and a 1979 172N...can't find a single amplified procedure where it says carb heat cold first.


-=0=LIR=0=-

[whipline]

And just to add to the C-150 story, the prop doesn't windmill when shut down, as I used to tell students before I actually saw it. Come to think of it I don't think the seminole did either.

[Bede]

BTW, "wind chill" has no effect on metal...just flesh.[/quote].

While the temperature of the engine "with wind" will never go below the OAT, a wind will cool down the engine much faster. Learned the hard way by not putting engine tents on a Navajo in -20 and 20 KT wind.

Had a student on a flight test lose all the oil in a Katana. Some gear shed a tooth and poked a hole in the case.

[harveymushman]

the reason for the carb heat on before jamming the throttles forward like so many people do in the winter is to avoid the caugh sputter then die. If it is -20 you wont be getting carb ice.

[gelbisch]

Exactly... it's got nothing to do with ice... it's like a shock factor with the cold air.

In any case, even if I can't explain it satisfactorily from a physics standpoint... go out and try it when it's -20 and see what happens. I'm only relating what DID happen, not what I THINK would happen...

[Right Seat Captain]

It's the difference between shoving cold or hot air into the engine when you put the throttle to full power. If you turn the carb heat off first, you're now throwing a bunch of cold air into the cylinders, that won't burn all that well. If you leave the carb heat on, you're now putting in warm air into the cylinders, much easier to burn in -20 C weather. Once you have the full power going, then you can change the air from warm to cold.

And in my C150M manual, the procedure for a balked landing, which is the same as an overshoot, clearly says full power first, then carb heat off.

[Cat Driver]

On the bug smashers such as the C150 the carb heat is controlled by the temperature of the exhaust pipe, the longer the engine is at low or idle power the cooler the exhaust pipe gets.

So when selecting carb heat prior to starting a low power descent if there already is an ice accumilation starting in the carb. you will be getting progressively less heat the longer the throttle setting is low....in otherwords even with carb heat selected hot, if there is insufficient heat in the exhaust pipe the efficiency of the carb heat is reduced depending on outside air temperature.

If the throttle setting has been near or at idle on a cold day applying power before selecting carb heat cold is the correct method, as there is not enough heat being supplied to cause any signifigant mixture problem until the exhaust temp increases to normal.

Cat

[LostinRotation]

It's the difference between shoving cold or hot air into the engine when you put the throttle to full power. If you turn the carb heat off first, you're now throwing a bunch of cold air into the cylinders, that won't burn all that well. If you leave the carb heat on, you're now putting in warm air into the cylinders, much easier to burn in -20 C weather. Once you have the full power going, then you can change the air from warm to cold.

Now i getcha. Makes perfect sense. We all had the same sequence in the overshoot, I wasn't arguing the point really, just looking for the common sense logic to it all.

Tnx guys

-=0=LIR=0=-

[hz2p]

I once had a runaway Hobbs meter in a rental 172. I was really sweating it - how was I going to come up with $75,943.27 at the flight school counter after I landed? - until I realized I had the tachometer to back me up.

I really inhaled a seat cushion over that one, let me tell you!

[scm]

wind chill will not affect an aircraft in flight since the airspeed is the same with or without a headwind. on the ground however...