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Thread: Bad decision/good decision? What doesn't kill us...

  1. #1
    SC3CM's Avatar
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    Bad decision/good decision? What doesn't kill us...

    Just read Cliff's post from the WAD flyin, and didn't want to hijack the other thread, but here's my little learning experience from the weekend. People will have different thoughts, but it may save someone one day so posting/talking abuot this stuff in my opinion is a great way to help others, and to learn.

    The family and I (wife, 11 yo son and 9 yo daughter) loaded up the Cherokee to head to Greenville. I would have loved to hit WAD in the Super Cruiser, but the kids love the float plane fly in so that's become a traditional family weekend.

    We flew up Friday from south of Boston and were in IMC most of the way at 5 and 7000 feet. We had to shoot the GPS 14 approach to 3B1, and didn't break out until just above mins, which is about pattern altitude there. I was right in line for joining downwind for RWY 03 which is what people were using and ended up #3 behind a nice Kodiak and a 182. It was a pretty uneventful flight until the prop stopped maybe .5 miles or so short of the rwy. I'm not 100% positive how far out we were or what our altitude was exactly because I was a bit distracted and forgot to gather these bits of info others I've spoken to after have thought I should have. At any rate, I kept the airspeed up, made the runway and rolled out long turning off on the taxiway and stopped.

    After a lot of thought/troubleshooting/double checking and what not, I figured it was almost certainly carb ice. I've always heard this would be a bit more noticeable with rough engine, drop in RPM etc..., but in our situation the prop just stopped. I had the power set at about 1600 RPM.

    What saved our a$$es??? Well, I tend to fly a higher faster pattern than the CFI's like for the Cherokee and have actually argued with a few at BFR time about this. I also had a long runway and with gusty winds to 17kts so only had 2 notches of flaps. Had I been on the numbers the CFI's would like to see there is a good chance I would have come up short of the runway. I did NOT have the carb heat on, because there had been no indication of carb ice, and prior to this, my SOP in the 180 (and ONLY in the 180 due to the design) was to put the carb heat on only if there were signs of carb ice. I always use carb heat in the Super Cruiser, and have always on Cessna's. I understand how and when carb ice is a factor, but relied too much on the thought that in the 180 you only use it when you have signs of carb ice.

    I learned my lesson there with what I feel was a pretty light slap on the wrist.

    Good decisions: I was high and slightly fast.
    Bad decision: Didn't use the carb heat prior to signs of carb ice.

    I got away with one, but as Cliff said I'm now a better pilot for it.

    Oh, and the ice cold beer I had that night couldn’t have been better!!!

  2. #2
    highroads's Avatar
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    Thanks for sharing this, I am always greedy for lessons learned, this story would be good for the AOPA "Never Again"

  3. #3
    OVEREASYGUY's Avatar
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    Thanks a bunch for sharing that with us. I too have always made an effort to come in high and fast so there is no risk of not making the ruwnay should the engine stop. I also like having lots of control - which I do have when not right around the stall speed.

    When I first started flying i would always try to make my approach something different each time - while my instructors always yell for consistancy. I would often come in too high and or too fast - then make myself deal with the issues and get down on the numbers. My belief is that one day when my engine does quit - I wont be where I want to be to make that field comfortably - and I better be able to do what is needed to get down and make it or make it into someones elses front yard.

    I wonder if when flying around a good practice might be to chop the throttle on final and then try hard to not touch it again - this way you'd always be pretty up to speed on landing with no power. If you are always flying an approach and adding in spirts of power - then when the engine quits you find yourself in a new situation and maybe come up short.

    I have a bad habbit of not using carb heat - now that fall/winter is around the corner I think I have to get a big sign on my instrument panel which says CARB HEAT!! Your story sure will help remind me!

    Someday I want to know what your wife said when the engine quit!

    cliff in Maine

  4. #4
    CubDriver218's Avatar
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    I've experienced carb ice in the C-180 more than once and it always grabs you by surprise, obviously no one likes to have the engine quit unexpectedly. However I don't use it on every approach and in the pattern on my cub because I was under the impression that with the carb bolted to the bottom of the sump it is always warm and far less likely for carb ice? I have not had any trouble in the 100 hours I've put on the PA-12 since I got it in December, however my emergency procedure which I go over and over in my head is if the engine quits.
    1.) Carb Heat
    2.) Switch Tanks
    both Immediately - if you wait to apply carb heat all that air going through the cowl will cool that engine down quick, you need to utilize the engines hot temperatures RIGHT NOW before it's too late.
    Please correct me if any of my thoughts are wrong.
    Fast or slow, always low, freedom of flight soothes the soul.
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  5. #5
    behindpropellers's Avatar
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    I have made two serious mistakes when flying that stand out:

    1. Shannon and I were going to a flyin at the WAD....this was 5 years ago. We had borrowed her uncles airplane to take up there. We took off in poor weather and headed east. Eventually the weather got bad and we turned around. We turned around and flew over 5 airports on our way home. As we were getting closer to home the ceilings started to drop.....in between airports. Trees near the tires....cell phone towers in view, clouds squeezing down. They were dropping fast and it was starting to get dark. I eventually made it into an airport 5 miles from home. Right before I was going to call ATC and climb into the clouds the airport came into view.

    Mistakes: 1. Thinking because you have a plane with big tires thinking you can just land anywhere. 2. Not landing when there was sufficient conditions to do it without worry.

    2. I followed another pilot when I did not know about the weather. This was a case of get theritis. Weather was on and off crappy the whole day. Some people got to leave....and never got out.....some came back. I followed somebody through unfamiliar terrain to leave. If we had left 5 minutes later we would have been able to get out or come back home.

    Mistakes: 1. Following another pilot (false decision making). 2. Departing with no 100% return plan.

    Those are mine. The weather is always blue skies the next day. Make your mistakes once but do not make them twice.

  6. #6
    mvivion's Avatar
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    I am amazed at how low the incidence of carburetor icing is in Warriors/Cherokees.

    BUT, as you document--it can happen, and I've had an engine just flat quit also--in a Super Cub. It does happen. Generally, as the carb icing accretes, the rpm drops off very gradually, and generally not noticed. In the condition that SC3 describes, he's in an atmosphere that is obviously saturated, since the clouds are just above pattern altitude, he's in a descent, with low power, and thus a cooling effect on the engine, and low power, ditto.

    This is the PERFECT setup for carburetor icing.

    And, if you don't believe it can happen to you, re-read the gent's story.

    Here's a question for you folks who DON'T use carburetor heat regularly:

    Why not? What's the down side to using carb heat on every approach to land, every time you reduce power below a certain rpm?

    I've never found any down side to using carb heat, EXCEPT of course, if I fail to select carb heat to cold as I initiate a go around, but again, using carb heat on every approach helps to get you into the habit pattern of also removing it on the go around.

    I'd really like to hear why anyone is reluctant to use carburetor heat routinely. Maybe there are some reasons I haven't thought of.

    I think this gent's story is a GREAT learning opportunity, and thanks to him for sharing.

    I too would like to hear the spouse's response to the engine stoppage.....maybe

    MTV

  7. #7
    CubDriver218's Avatar
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    I believe I was told that carb heat is hard on the valves so not to use it for prolonged periods of time? During my run-up my RPM drop is sometimes just barely noticable when I apply carb heat. What is the prefered drop? I just had my carb apart and was looking at it and it appears that my carb heat is closing the outside air door properly however my RPM drop is minimal.
    Fast or slow, always low, freedom of flight soothes the soul.

  8. #8
    pzinck's Avatar
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    I like mike would also like to know why people would'nt use carb heat ? If it's there and i am low rpm, i use it. I have almost killed myself 3 times in very marginal vfr. I am now afraid of it. Since being sick some years ago my confidence has waned. Without an artificial horizon in the cub, it really scares me to push weather. It is a bad feeling once weather has closed in around your tailside. My skills using secondary (floating compass , airspeed, altimeter, and rate of climb ) in a cub are not that good. 3 times in my life i have done this in 0 visibility. I promised if i ever do it again and live i will quit flying. Some may think zinck has no balls, they ain't far off from the truth. In the skywagon with an artificial horizon i feel a little more confidence . Do most people have attitude indicators in their cubs?

  9. #9
    cafi19's Avatar
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    I was taught to pull the carb heat on when I do my pre landing check. I dont think of landings as "prolonged periods of time"....so I think you are ok there.

    I was also taught....and correct me if I am wrong....that carb ice is possible any time between 20 and 70 degrees F....obviously saturated air or not.

    Glad everything worked out well!

    I worry about the thought that pushing in bad weather makes you a better pilot (not saying that the original poster pushed weather as I assume the proper ratings for the conditions). From what I read in the other thread....that was not a good decision and indicators should have caused you to turn back and not forge ahead.

    Here is what one of the smart guys did. He landed Looks like an EXCELLENT decision!!!


    Others turned back and went a different route that proved better. And other still...waited. A few hours later it was much better!

    We dont HAVE to be anywhere....so let's be safe!

    cafi

  10. #10

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    Quote Originally Posted by mvivion
    I've never found any down side to using carb heat, EXCEPT of course, if I fail to select carb heat to cold as I initiate a go around, but again, using carb heat on every approach helps to get you into the habit pattern of also removing it on the go around.
    MTV
    Agreed....

    In Lycoming powered aircraft, simply closing the carb heat on short final (when going to full flaps is a good time) is a good habit pattern to prevent icing on the approach and make full power available for a potential go-around. This also prevents ground operations in dirty conditions (unfiltered air).

    I've flown a few Lyc powered aircraft in hot weather that would almost quit running if carb heat was applied. If the OAT is above 70F and the dewpoint spread is at least 20 degrees, there is little chance of carb icing.

    Seems to me it all comes back to common sense. If icing conditions prevail, especially when operating at low altitude at lower power.... a pilot shouldn't have to think twice about lowering the risk of icing by using partial or full carb heat.
    .

  11. #11
    SC3CM's Avatar
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    My wife grew up in small planes and loves to fly, so I got lucky there for sure. We have several hundred hours flying across the country with the kids, in IMC, sometime in some pretty bumpy conditions and she sees to know when not to offer her thoughts (this only applies when we are flying though ). She said absolutely nothing until the next day, and then just wanted to be sure I knew what happened and wouldn't do it again. Of couse on the ride home (after a thorough check out an over an hour above the field at 5k' by myself on Saturday) though, anytime we got near a cloud she got a bit nervous. We flew final high and fast again, with no issue, and the carb heat on, and when we landed my daughter congratulated me on keeping the engine on the whole time!

  12. #12

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    Quote Originally Posted by SC3CM
    and when we landed my daughter congratulated me on keeping the engine on the whole time!
    Ya gotta love the honesty of kids.... no matter how brutal it can be at times.

  13. #13

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    I always use carb heat even If I'm not landing but decide to pull the power below 1500 to descend.
    Most planes I've flown have around 1000 RPM or less drop when applying the carb heat but my Cub drops 1500 RPM, and on a 90 degree plus day it will drop more than 2000 RPM. I usually shut the carb heat on short final but doing a touch and go and forgetting to shut off the carb heat is an eye opener, it don't take long for me to know I forgot something.

    Thanks for sharing your story.

  14. #14

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    I was taught to pull carb heat mid field on downwind before the throttle is reduced. I do it EVERY time, irregardless of what plane or engine I am flying, even if it is 105 degrees on a Central CA afternoon with very low humidity....the carb heat comes on. If I have to go around, it comes off after I go to full power. The carb heat goes off after I land and am rolling out.

    I can't imagine why anyone would never pull carb heat on every landing.

  15. #15
    JP's Avatar
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    I iced twice on Sunday. Despite that I fly with a C-90 (which is notorious for icing), it was the first time in a long time that I picked up a bit of ice. Mine gives me all kinds of warning, fortunately, and clears out quickly with the carb heat on.

    As always, when in doubt, don't. Never, ever bust your personal minimums. Discretion is the better part of valor. It's a lot better to be on the ground wishing you were in the air than the other way around.
    JP Russell--The Cub Therapist
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    Thanks Bowie thanked for this post

  16. #16

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    [quote] In Lycoming powered aircraft, simply closing the carb heat on short final (when going to full flaps is a good time) is a good habit pattern to prevent icing on the approach and make full power available for a potential go-around. This also prevents ground operations in dirty conditions (unfiltered air). [quote]


    Not disagreeing with you so much as just offering a slightly different take on it.

    I believe leaving the carb heat on all the way to the ground is the safest. Here's why. Worst case scenario, and what we're all trying to avoid. You turn the carb heat off on short final. And unknowingly you start to make ice immediately. Then for whatever reason you have to go around. So you then apply full throttle and what happens? Now your making even more ice with the increased volume of air rushing through the carb at full throttle. You now feel the power slipping away and are forced to use carb heat to break it up and ingest all of that ice and water at the absolutely worst possible time, while trying to arrest the descent and start climbing out, i.e. low and slow. Not good.

    Worst case scenario for leaving it on would be. You apply full throttle, and notice a slight reduction of power from being overly rich, you'll still be getting nearly full power and it won't be getting any worse, unlike what it would be with ice continuing to accrete in the carb throat. You now can arrest the descent and slowly turn off the carb heat and climb out with full power and without any chance of carburetor ice.

    I use carb heat on the ground all the time on a regular basis out of necessity to help get my # 5 and 6 cylinders on a 0470 to "light off" when it's cold. And also use and leave it on while on the runway, as described above. I get regular oil analysis done at every oil change and have never had any issues/problems/concerns with any of my engines from using unfiltered air. At low power and the brief exposure they get of unfiltered air just doesn't seem to have any negative long term effects. At least in my experience, on my engines it hasn't. Corrosion will kill them long before ingesting a little dust will. Within reason of course.

    BTW: Jet engines don't use an air filter, and they all seem to do just fine!

  17. #17

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    [quote="WSH"][quote] In Lycoming powered aircraft, simply closing the carb heat on short final (when going to full flaps is a good time) is a good habit pattern to prevent icing on the approach and make full power available for a potential go-around. This also prevents ground operations in dirty conditions (unfiltered air).


    Not disagreeing with you so much as just offering a slightly different take on it.

    I believe leaving the carb heat on all the way to the ground is the safest. Here's why. Worst case scenario, what we're all trying to avoid. You turn the carb heat off on short final. And unknowingly you start to make ice immediately. Then for whatever reason you have to go around. So you then apply full throttle and what happens? Now your making even more ice with the increased volume of air rushing through the carb at full throttle. You now feel the power slipping away and are forced to use carb heat to break it up and ingest all of that ice and water at the absolutely worst possible time, while trying to arrest the descent and start climbing out, i.e. low and slow. Not good.

    Worst case scenario for leaving it on would be. You apply full throttle, and notice a slight reduction of power from being overly rich, you'll still be getting nearly full power and it won't be getting any worse, unlike what it would be with ice continuing to accrete in the carb throat. You now can arrest the descent and slowly turn off the carb heat and climb out with full power and without any chance of carburetor ice.

    I use carb heat on the ground all the time on a regular basis out of necessity to help get my # 5 and 6 cylinders on a 0470 to "light off" when it's cold. And also use and leave it on while on the runway, as described above. I get regular oil analysis also and have never had any issues/problems/concerns with any of my engines from using unfiltered air. At low power and the brief exposure they get to unfiltered air just doesn't seem to have any long term effect. At least in my experience, on my engines it hasn't. Corrosion will kill them long before ingesting a little dust will. Within reason of course.

    BTW: Jet engines don't use an air filter, and they all seem to do alright!
    Carb icing is a gradual process, especially if not flying in visible moisture. The brief period on short final is insignificant. Applying full throttle with carb heat on (especially in warmer conditions and high density altitudes) can create a rich mixture that will cause a large loss of power available.... and often make the engine "stumble" as it tries to accelerate to full rpm. Also, a low altitude abort can be high stress for the pilot which might inhibit the pilot from "remembering" to turn the carb heat off. I've seen this many times with numerous students... and also IFR training pilots who tend to think less about the airplane when faced with missed approach procedures, etc.

    As for ground operations.... I've seen air conditions so dirty that visibility is a problem.... stuff I don't want going into the engine.

    and.... I've seen the inside of several jet engines and the repair of the damage from sand and grit costs tens of thousands of $$

    Not trying to be argumentative here... just passing on what I've seen in almost 50 years of operating a lot of different aircraft in many conditions
    .

  18. #18

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    I Talked with your wife a little but she didn't say anything about the icing, glad it all worked out and you're all safe as you have a very nice family and it was nice to meet both kids, as much as you are in Maine you may as well move up this way. I flew to Greenville on Thursday and pulled the carb heat on a number of times as there was a lot of moisture in the air and on the windshield at times. As Jeff said of the c-90 it's a nice ice machine. I know you will think about this for a long time and will add it to the list of things to look out for. Take care and thanks for sharing the story. Douten

  19. #19
    mvivion's Avatar
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    SC3,

    You hang onto that girl!!! She's a good one.

    I use carb heat regularly on approach, abeam the numbers on downwind, about where I reduce power.

    I leave it on to the landing. If I need to go around, I push up the power and a 1/4 second later push carb heat to cold. That's the way I've done it for decades, and it's ingrained.

    Now, IF it's really HOT out, I MAY opt not to use carb heat. Just to be different. But, like most things in aviation, this should be the result of a conscious thought process, not just doing by rote.

    Richard,

    Carburetor heat application, even for extended periods of time will not harm the valves, if done in flight.

    The only real down side to use of carb heat is that generally you are putting unfiltered air into the engine, so extended operations with carb heat to hot on the ground should be avoided to prevent induction of debris.

    Otherwise, I sure don't see any down side to using carburetor heat every time you land or reduce power.

    When I flew in Kodiak (land of perpetual carburetor icing) my procedure was to pull on carb heat for 30 seconds every time I crossed a bay in the Cub. I had some interesting moments in that Cub in Kodiak. The temperatures and humidity there are nearly perfect for carburetor icing. And, it was worse in my 180.

    MTV

  20. #20
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    Sunday, I was following Tim (2+2) with Dick (Champ) following me heading west to get out of the VT mountains. I tried to slow down for the slower Champ as we were winding our way thru low clouds and moist cool air. I had to periodically use carb heat with a noticable jump in increased rpm most of the time. I eventually added more power (but had then had to get out of line) that reduced the problem until I broke free of the VT conditions. My early in production O-320 when overhauled in the mid-90s was changed from an A1A to an A1B. Not sure but I think the change was in the carb/intake area. Maybe that has something to do with my engine seemingly being more sensitive to carb ice than other later O-320 versions.

    Long ago with my then young wife, traveling in a C170 over NC farm land, the engine began running rough. We had problems with a weak cylinder so I convinced myself that that was the problem. But it was rapidly getting worse. I was adding more and more throttle until I ran out of throttle and we started to decend. After picking out a field and on a base of sorts, it popped in to my head to check the carb heat. Man, what a supprise! That plane shook and coughed and then developed full power and an immediate climb! My wife was quiet through the whole thing.

    I was told long ago that is was not uncommon that some pilots were forced to land only to find water dripping from their carb when on the ground.
    Jim Newton
    --------------

  21. #21

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    [quote="HydroCub"][quote="WSH"]
    In Lycoming powered aircraft, simply closing the carb heat on short final (when going to full flaps is a good time) is a good habit pattern to prevent icing on the approach and make full power available for a potential go-around. This also prevents ground operations in dirty conditions (unfiltered air).


    Not disagreeing with you so much as just offering a slightly different take on it.

    I believe leaving the carb heat on all the way to the ground is the safest. Here's why. Worst case scenario, what we're all trying to avoid. You turn the carb heat off on short final. And unknowingly you start to make ice immediately. Then for whatever reason you have to go around. So you then apply full throttle and what happens? Now your making even more ice with the increased volume of air rushing through the carb at full throttle. You now feel the power slipping away and are forced to use carb heat to break it up and ingest all of that ice and water at the absolutely worst possible time, while trying to arrest the descent and start climbing out, i.e. low and slow. Not good.

    Worst case scenario for leaving it on would be. You apply full throttle, and notice a slight reduction of power from being overly rich, you'll still be getting nearly full power and it won't be getting any worse, unlike what it would be with ice continuing to accrete in the carb throat. You now can arrest the descent and slowly turn off the carb heat and climb out with full power and without any chance of carburetor ice.

    I use carb heat on the ground all the time on a regular basis out of necessity to help get my # 5 and 6 cylinders on a 0470 to "light off" when it's cold. And also use and leave it on while on the runway, as described above. I get regular oil analysis also and have never had any issues/problems/concerns with any of my engines from using unfiltered air. At low power and the brief exposure they get to unfiltered air just doesn't seem to have any long term effect. At least in my experience, on my engines it hasn't. Corrosion will kill them long before ingesting a little dust will. Within reason of course.

    BTW: Jet engines don't use an air filter, and they all seem to do alright!
    Carb icing is a gradual process, especially if not flying in visible moisture. The brief period on short final is insignificant. Applying full throttle with carb heat on (especially in warmer conditions and high density altitudes) can create a rich mixture that will cause a large loss of power available.... and often make the engine "stumble" as it tries to accelerate to full rpm. Also, a low altitude abort can be high stress for the pilot which might inhibit the pilot from "remembering" to turn the carb heat off. I've seen this many times with numerous students... and also IFR training pilots who tend to think less about the airplane when faced with missed approach procedures, etc.

    As for ground operations.... I've seen air conditions so dirty that visibility is a problem.... stuff I don't want going into the engine.

    and.... I've seen the inside of several jet engines and the repair of the damage from sand and grit costs tens of thousands of $$

    Not trying to be argumentative here... just passing on what I've seen in almost 50 years of operating a lot of different aircraft in many conditions
    .

    Respectfully, if the engine is "stumbling" with the application of carb heat and full throttle, then the mixture is not adjusted properly for the current conditions. A separate issue, if you will and should have been already sorted out in the pattern, prior to landing.

    And it's not that turning it off on "short final" is so significant. It's that the carb heat is off when you could likely need it the most, when your much more likely to develop carb ice, going to full throttle. With the mixture set properly, it's a non-issue and no carb ice is assured. With the carb heat already turned off, it's a crap shoot!

    Of course, We've all seen extreme conditions and the exception rather than the rule and common sense should prevail. However, if it happens to be so "dirty" that visibility is problem, then your going to ingest the "dirt" whether your on the ground or in the air.

    It seems to me most Jet engines do just fine under normal conditions over their lifetime without an air filter. Flying through Volcanic ash and a Haboob notwithstanding!

    BTW: And I'm NOT taking your opinion as being "argumentative"! Keep it coming
    Likes Bowie liked this post

  22. #22
    Bill Ingerson's Avatar
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    Carb Heat

    Good Subject:

    Going back to my Ground school in 1972, I was taught as already mentioned to pull the throttle back when passing the numbers on the runway prior to landing then pull out the carb heat. Never part way but slowly open it all the way. Put the first notch of flaps in then turn base, full flaps then turn off the carb heat and turn final and land. I use the carb heat probably more than needed. Never had a indication of carb heat in my SuperCub yet but while traveling around I will throttle back about every 30 minutes put in a little carb heat, opened all the way of course then put it back where it was and continue on. I do this all year around. Guess I just worry to much, but have not had any problem using this method yet, only when I forget to turn it off on take off going around do I notice a drop in power.

    Bill

  23. #23
    StewartB
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    Whether or not I use carb heat depends on the day. On on downwind, off on final. If I use it at all.

    If I ever touch down with carb heat on I've screwed up. Been there, done that, never again.

    SB

  24. #24
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    If you want to fly in the NE you have to get used to low ceilings and moist air most of the year even in winter on rare day's, my C90 in my Pa11 never made ice that I knew of in over 2000 hrs but the C90 champ I had stopped running on me in the middle of the Adirondacks on skis one warm winter day because the Pa11 made me less aware of looking for an ice problem untill it got very quiet in the Champ that day, pulled carb heat and set up best glide speed to nowhere and kept it windmilling and after what seemed like a long time but only really 10 to 20 seconds it started to cough and sneeze with a few barks thrown in and then it returned to normal RPM and flew from ice covered lake to ice covered lake till I was sure that it was all caused by carb ice, I now pull it on when I'm about a mile out while there's still alot of heat in the exhaust and push it off on short final. I fly in the mist and rain all the time and pull it on every 10 min or so now mostly because it makes me feel better.

    Glenn

  25. #25
    JP's Avatar
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    Don't forget to use it during taxi on dew, misty wet grass on those lovely New England late summer early mornings...you can pick up a lot of moisture on the way to departure that may result in ice.
    JP Russell--The Cub Therapist
    1947 PA-11 Cub Special
    www.bloomerrussellbeaupain.com

  26. #26
    Tim's Avatar
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    I put 1800 hours on my 2+2 with an 0-320 narrow deck and fly in the same conditions Glenn described and have never experienced carb. ice.

    On the ride home from NH. the other day that Jim mentioned, I was at reduced throttle slowing for the Champ also, and no ice. I check the carb. heat on runup, thats about the only time I use it

    Tim

  27. #27
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    Delete

  28. #28
    mvivion's Avatar
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    I flew a Super Cub in Kodiak for a couple years and quite a few hours, and really never experienced much carb ice.

    Engine was at TBO, so the engine was changed and new fabric on the plane at the same time. The new engine was a Lyc reman.

    THAT engine made carb ice LIKE CRAZY, which is when I started pulling on carb heat every few minutes in flight. I never figured out what changed, other than the engine. I was told the air box was the same, but whatever happened in the rebuild process, that airplane was a whole different beast when it came to making carb ice.

    MTV

  29. #29
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    Quote Originally Posted by Fuel
    Most planes I've flown have around 1000 RPM or less drop when applying the carb heat but my Cub drops 1500 RPM, and on a 90 degree plus day it will drop more than 2000 RPM.
    I'm interested to know what the real numbers are I'm looking for during my run-up. I'm assuming Fuel has 1 too many zeros in his calculation. I'll pay close attention on my way to Fall Colors on Thursday but I believe I normally only see about a 25RPM drop IF THAT and I thought 50 RPM sounded about right which is what I think we get in the 180 at least. In the 180 I can hear and feel it working, the cub is very subtle when I apply carb heat, almost unnoticable but I do get a little drop. Should this be reason for concern?
    Thanks
    Fast or slow, always low, freedom of flight soothes the soul.

  30. #30
    StewartB
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    I get 200rpm drops when running up at 1600-1800. Cessna or -12, both are similar.

    SB

  31. #31
    behindpropellers's Avatar
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    Maybe we should change the title of this thread to something about carb ice?

  32. #32

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    Quote Originally Posted by Richard Deblack
    Quote Originally Posted by Fuel
    Most planes I've flown have around 1000 RPM or less drop when applying the carb heat but my Cub drops 1500 RPM, and on a 90 degree plus day it will drop more than 2000 RPM.
    I'm interested to know what the real numbers are I'm looking for during my run-up. I'm assuming Fuel has 1 too many zeros in his calculation. I'll pay close attention on my way to Fall Colors on Thursday but I believe I normally only see about a 25RPM drop IF THAT and I thought 50 RPM sounded about right which is what I think we get in the 180 at least. In the 180 I can hear and feel it working, the cub is very subtle when I apply carb heat, almost unnoticable but I do get a little drop. Should this be reason for concern?
    Thanks
    Well, more than anything, it depends on where you have the mixture set.

    And, to reduce plug fouling and "gumming" up the exhaust guides with excessive fuel byproducts, you should have the mixture leaned brutally on the ground, to the point the engine stumbles when adding more throttle. Your NOT making enough power to do any damage to anything in the engine, so lean it until it stumbles, and then en-richen just enough for smooth operation while on the ground. Then the RPM will actually go UP, when you add carb heat, which makes the mixture richer and puts you back on the ROP side at about "best power", if done right.

    So the main thing is to see some change in RPM's, one way or the other, just to let you know it's working, the amount is not that important. Your also checking for full, smooth, easy, movement of the carb heat cable and airbox.

  33. #33

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    Quote Originally Posted by Richard Deblack
    Quote Originally Posted by Fuel
    Most planes I've flown have around 1000 RPM or less drop when applying the carb heat but my Cub drops 1500 RPM, and on a 90 degree plus day it will drop more than 2000 RPM.
    I'm interested to know what the real numbers are I'm looking for during my run-up. I'm assuming Fuel has 1 too many zeros in his calculation. I'll pay close attention on my way to Fall Colors on Thursday but I believe I normally only see about a 25RPM drop IF THAT and I thought 50 RPM sounded about right which is what I think we get in the 180 at least. In the 180 I can hear and feel it working, the cub is very subtle when I apply carb heat, almost unnoticable but I do get a little drop. Should this be reason for concern?
    Thanks
    Well, more than anything, it depends on where you have the mixture set.

    And, to reduce plug fouling and "gumming" up the exhaust guides with excessive fuel byproducts, you should have the mixture leaned brutally on the ground, to the point the engine stumbles when adding more throttle. Your NOT making enough power to do any damage to anything in the engine, so lean it until it stumbles, and then en-richen just enough for smooth operation while on the ground. Then the RPM will actually go UP, when you add carb heat, which makes the mixture richer and puts you back on the ROP side at about "best power", if done right.

    So the main thing is to see some change in RPM's, one way or the other, just to let you know it's working, the amount of RPM change is not that important. Your also checking for full, smooth, easy, movement of the carb heat cable and airbox.

  34. #34
    OVEREASYGUY's Avatar
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    So suppose the engine does quit on final and it's carb ice. After it quits you pull carb heat and try to restart - how long is it apt to take one to restart it?

    And might the ice be so bad it simply wont start?


    with the engine stopped - will carb heat on do anything to melt the ice? Or do you need the engine running for carb heat to get into the carburetor?

    cliff in Maine

  35. #35
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    Quote Originally Posted by OVEREASYGUY
    So suppose the engine does quit on final and it's carb ice. After it quits you pull carb heat and try to restart - how long is it apt to take one to restart it?

    And might the ice be so bad it simply wont start?


    with the engine stopped - will carb heat on do anything to melt the ice? Or do you need the engine running for carb heat to get into the carburetor?

    cliff in Maine
    An engine quitting on final is irrelevant if you understand how to properly set up an (power off) approach with a thourough understanding of "the power curve".

    Tim

  36. #36
    StewartB
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    Quote Originally Posted by behindpropellers

    An engine quitting on final is irrelevant if you understand how to properly set up an (power off) approach with a thourough understanding of "the power curve".

    Tim
    Huh? You'll need to enlighten me. A quiet engine is always relevant.

    SB

  37. #37
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    Quote Originally Posted by StewartB
    Quote Originally Posted by behindpropellers

    An engine quitting on final is irrelevant if you understand how to properly set up an (power off) approach with a thourough understanding of "the power curve".

    Tim
    Huh? You'll need to enlighten me. A quiet engine is always relevant.

    SB
    Why is it relevant if you are on final approach already set up for landing?

    I consider set up for landing as no power, perfect speed and descent angle.

    If you are dragging it in with power....it is relevant.

    Fumbling around switching tanks and carb heat on final is a waste of time when you should be flying the plane.

  38. #38
    StewartB
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    Thorough understanding of the power curve? Precision landings require airspeed control, pitch, and glide path control, power. I use both. Both are important. As the wind changes and my loads change I can't anticipate how to fly power off with acceptable accuracy to a spot landing.

    A quiet engine on final is an emergency in my book. If its caused by carb ice that's pilot error, but its still an emergency.

    SB

  39. #39
    behindpropellers's Avatar
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    Quote Originally Posted by StewartB
    Thorough understanding of the power curve? Precision landings require airspeed control, pitch, and glide path control, power. I use both. Both are important. As the wind changes and my loads change I can't anticipate how to fly power off with acceptable accuracy to a spot landing.

    SB
    You can use pitch to control your airspeed and glide path. Power curve has nothing to do with that hunk of aluminum and steel on the front of the plane.

    Find a good glider guy to explain it to you.

  40. #40

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    Quote Originally Posted by Richard Deblack
    Quote Originally Posted by Fuel
    Most planes I've flown have around 1000 RPM or less drop when applying the carb heat but my Cub drops 1500 RPM, and on a 90 degree plus day it will drop more than 2000 RPM.
    I'm assuming Fuel has 1 too many zeros in his calculation.
    Thanks
    No wonder my engine nearly dies, it would with a 2000 RPM drop.

    I have one too many zeros. I meant 100, 150 and 200 RPM drops.

    I have a very noticeable drop when I use carb heat regardless of the outside air temp.

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