Zeldman
Touchdown! Greaser!
OWT.
Near Engine Failure Tonight
- Thread starter steviedeviant
- Start date
OWT.
Clip4
Touchdown! Greaser!
Which is a known problem in Piper PA28 with a service bulletin to remove and test the muffler.
N659HB
En-Route
Seems lately there are more engine failures on takeoff.
Clip4
Touchdown! Greaser!
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danhagan
En-Route
I've had these in the rentals, that caused RPM reductions
1. Carb ice after landing on TNG, full power than loss as soon as no useable runway
2. Mag failure
3. Exhaust baffle worked loose
After those and a couple of other issues, I got my own plane
1. Carb ice after landing on TNG, full power than loss as soon as no useable runway
2. Mag failure
3. Exhaust baffle worked loose
After those and a couple of other issues, I got my own plane
ElPaso Pilot
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ElPaso Pilot
"Seems lately" depends heavily on what the news is reporting, what is in the forums, what is near you, and what you happen to be paying attention to.
On the other hand, what does Nall, or any other data source say? It was flat to declining over a decade last time I looked.
N659HB
En-Route
Sorry, I meant lately (past couple of weeks) there are more crashes on takeoff.
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Bob Gardner
Let's all dig out our copies of "Key Reprints from the Lycoming Flyer" to see what the engine manufacturer has to say.
http://11hc.44rf.com/manuals/engine-prop/lycoming/lycoming---flyer_key_reprints.pdf
Bob
http://11hc.44rf.com/manuals/engine-prop/lycoming/lycoming---flyer_key_reprints.pdf
Bob
brien23
Cleared for Takeoff
Your lucky your still alive oh wait that was a Piper not a Cessna your alright.
Harold Rutila
Pre-takeoff checklist
It's entitled "Don't Touch Carb Heat Until You've Seen This," which is a shameful attempt at "dispelling" a "rumor" that the carb heat shouldn't be used in Pipers, relying on an example of agricultural pilots who don't use it because they fly low near sediment and grass, a condition that does not apply to 90% of that channel's viewing audience.
The NTSB has previously released safety bulletins stressing the importance of using the carb heat. The FAA has an entire AC about it. Meanwhile we have Youtube video creators telling Piper pilots not to bother with it, because "carb ice never happens in Pipers." One of top comments below the video is portrays the narrator as a dispeller of "old man aviation myths."
The lack of understanding of carburetor ice has caused fatal accidents in Pipers, and there is no excuse for people to be spreading misinformation based on one or two anecdotal examples of when use of carburetor ice may not be advantageous.
To quote the narrator, he says: "Lastly, in any type of aircraft, carb heat should never be used when outside of well-known carburetor icing conditions, which can be ascertained by this simple chart." The chart he shows is adapted from the Airplane Flying Handbook, Figure 7-12. The description of that figure specifically states "Although carburetor ice is most likely to form when the temperature and humidity are in ranges indicated by this chart, carburetor icing is possible under conditions not depicted."
Anyway, I digress. I would guess the issue with the Cherokee 140 in this thread is carburetor or magneto related. Fouled spark plug(s) or carb ice seem likely given the conditions.
denverpilot
Tied Down
A fouled plug would have shown up in his ground mag check.
But I have seen a fouled plug in flight once in a 172RG and the symptoms were nearly the same.
I'm going with busted muffler baffle on that aircraft, for the guessing pool.
steviedeviant
Pre-takeoff checklist
I haven't head back from the owner of the plane yet, and I hope they can possibly tell me something tomorrow. However, consider this: On my second touch and go, I had the carb heat on and turn it off prior to my third departure. That means the ice would have had to form in a very short amount of time (from time it takes to get from upwind to the downwind about mid field). When I pulled it back, the rpm dropped a lot and then moved immediately back up to about 1700 RPM and never would go above that. I was thinking if it has knocked some ice lose, that after 30 seconds or so it would have been done and everything would have been fine. Also, the engine ran rough all the way to landing, so again, however long it took me to go ahead and get the plane down.
With that said one more question: If you were taking off in a potential condition of carb icing, I assume you wouldn't have carb heat on during takoff but would do it at cruise. So when do some of you turn on yor carb heat when you suspect conditions could warrant carb icing?
steviedeviant
Pre-takeoff checklist
As soon as I hear back from the school I will post it here - or least what they think it is.
I have to admit, all this discussion is helpful, but I sure as heck hope this wasn't some carb ice situation. I realize this wasn't a big deal for some of your more experienced guys, but with me an 100 hours, the more I think about it more the I realized it as a somewhat disturbing experience for me. I don't want to spend all my worry on carb ice!vvI was suppose to go up in another plane on Saturday and backed out because I wanted to wait and hear back from the school to be sure it wasn't something stupid I did. Even though there was moister in the air from the storm that went through, everything I am reading makes me believe this was something mechanical. I hope to know something tomorrow and as soon as I do will post.
PaulS
Touchdown! Greaser!
Did you leave the carb heat on once you pulled it on?
denverpilot
Tied Down
Plenty of time to form. It doesn't take a whole lot of ice to create a problem in a carb. And sometimes it does take many many seconds for carb heat to work to remove it. Especially at lower power settings. And carb ice *creates* a lower power setting... see the Catch 22?
I still think it's something else, but just answering your questions.
As far as takeoff goes, there's a lot of heat being produced in the engine compartment and depending on the location and mounting of the carb, this helps protect against carb ice in a way.
In my "likes to make carb ice" 182 (that's the airport gossip anyway, I've not experienced serious carb ice more than a handful of times in it, but the general consensus is that a 182 will make carb ice and most Pipers like you're flying rarely do) in conditions "ripe" for Carb ice, I watch the manifold pressure for unexplained/uncommanded drops and will even occasionally "check" in cruise or long low power approaches or descents by noting the MP, applying carb heat for at least 20-30 seconds (no rush), and then removing it if no signs of stumble or ice melt off, and noting the MP again. If it came up an inch or more without touching the throttle it's a big hint that my carb is making small amounts of ice. If the engine suddenly coughs as a blob of ice melts at about the 15-20 second mark, it's making a LOT of ice and the carb heat goes back on and stays on.
Like I said though, this is a rare event on an engine and carb combo known to "make ice" unlike your Piper. I've seen this maybe happen ten times in almost a decade of owning it. Probably less.
But my procedures for long low power descents definitely include carb heat on and wait. The melting process often isn't fast when making low power.
Dan Thomas
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In the OP's description, the engine ran a little rough when the RPM loss occured. A busted piece of muffler baffle blocking the outlet shouldn't cause roughness. A piece of the intake SCAT hose folding inward and partially blocking induction air, or a failed Brackett filter screen (AD on that) letting the foam filter get in there, could both drop the RPM by reducing air, and making the engine rough by increasing the mixture due to the choking effect.
A mag gone rogue will do it, too. The plastic distributor gears can wear badly enough that they slip a few teeth and start sending sparks to the wrong plugs. That sets off intake air/fuel in whatever cylinder that's on its intake stroke, maybe backfiring right back through the induction system, reducing power enormously and making lots of roughness. That's why they give us mag switches: to shut off a rogue mag so we can continue safely on the good mag.
Maybe the engine burned a valve. Or a valve started sticking. Or an intake hose failed, leaning the induction system, especially the cylinder nearest the failed hose. RPM loss and roughness.
The usual fuel-supply guesses, again. Fuel system troubles are really rare. Really, really rare. If the fuel flow is reduced somehow, the engine leans badly and quits. Dead. It might run at a much-reduced throttle setting, but if you open the throttle much, the mixture goes beyond the combustible range and the engine quits. Water in the fuel? It will either suck it through the main jet and burp a bit and continue OK, or it will refuse to pass through the jet (surface tension) and the engine quits.
The fact that the OP couldn't get more than 2000 RPM on a runup after landing tells me that there's a mechanical or electrical problem here. Carb ice should have either killed it or have melted in the engine's heat after landing.
A mag gone rogue will do it, too. The plastic distributor gears can wear badly enough that they slip a few teeth and start sending sparks to the wrong plugs. That sets off intake air/fuel in whatever cylinder that's on its intake stroke, maybe backfiring right back through the induction system, reducing power enormously and making lots of roughness. That's why they give us mag switches: to shut off a rogue mag so we can continue safely on the good mag.
Maybe the engine burned a valve. Or a valve started sticking. Or an intake hose failed, leaning the induction system, especially the cylinder nearest the failed hose. RPM loss and roughness.
The usual fuel-supply guesses, again. Fuel system troubles are really rare. Really, really rare. If the fuel flow is reduced somehow, the engine leans badly and quits. Dead. It might run at a much-reduced throttle setting, but if you open the throttle much, the mixture goes beyond the combustible range and the engine quits. Water in the fuel? It will either suck it through the main jet and burp a bit and continue OK, or it will refuse to pass through the jet (surface tension) and the engine quits.
The fact that the OP couldn't get more than 2000 RPM on a runup after landing tells me that there's a mechanical or electrical problem here. Carb ice should have either killed it or have melted in the engine's heat after landing.
nrpetersen
Line Up and Wait
This all is why we installed a manifold pressure gage and an EGT gage in our 172M when new even tough it was a fixed pitch propeller. With ice, we could see only some reduction in power from reduced manifold pressure but we could also see that the mixture had gotten rich reducing the EGT. This was a Lycoming engine (O320E2D) which was not known for icing but many times we could see that it would ice up only slightly and then not get any worse. But the combination of these two gages could assure us that the engine was properly mixing and burning fuel to make power.
To the OP - was the engine running smoothly at reduced power or was it rough? If smoothly, I'd also first look up the exhaust stack with a flashlight to see if the muffler was disintegrating from the inside. If the engine was suddenly rough I'd suspect fouled plug/ignition lead or stuck valve or some other single cylinder problem etc.
There is a lot to cover in a PPL instruction, but I wish there was a way more attention could be given to engine theory and diagnosis.
To the OP - was the engine running smoothly at reduced power or was it rough? If smoothly, I'd also first look up the exhaust stack with a flashlight to see if the muffler was disintegrating from the inside. If the engine was suddenly rough I'd suspect fouled plug/ignition lead or stuck valve or some other single cylinder problem etc.
There is a lot to cover in a PPL instruction, but I wish there was a way more attention could be given to engine theory and diagnosis.
WannFly
Final Approach
I am not saying blindly trust what he said in the video or that piper will never produce ice. I am saying just because it has carb doesn't mean carb heat is required. If it was the case, piper would have put that in POH. The inlet design makes a lot of sense, but I am very low time student, so I will be interested to hear an APs opinion. Just because there is an AC, doesn't mean we throw out the POH or what the carb temp probe is saying. That is the specific reason i got a carb temp probe and after flying with it in ripe ice conditions, I have never seen the carb temp to go down below 46 degrees. There is no point applying carb heat when the temp is that high.
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Harold Rutila
Pre-takeoff checklist
Please go read the NTSB Safety Briefing on carburetor icing. The Piper POH guidance was directly criticized by NTSB as a contributor to several Piper carb ice-related accidents. So yes -- what I am saying in this instance is that you do disregard the POH guidance on carburetor heat because newer research and guidance as a result of accidents supersedes it. If you have a carb temp monitor, that's great and it can be used as you specified, but I'm talking about airplanes that don't have such a tool.
WannFly
Final Approach
Makes sense, may be because of the POH pilots get into the mode of I am flying piper hence forget carb temp.
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Harold Rutila
Pre-takeoff checklist
Agreed. I see it a lot, unfortunately.
JonH
Pre-takeoff checklist
400 RPM sound like more than losing a mag. With ice I doubt you'd get stuck at any particular RPM, it should get better or worse, but what do I know. I'm looking forward to hearing the determination.
I hope you get a maintenance flight out of it
I've had 3, none were engine related, thank god!
I hope you get a maintenance flight out of it
I've had 3, none were engine related, thank god!
I flew for years on an GOpher engine with a pressure carb. The pressure carb was more of a throttle-body fuel injection system than a carb and presumed resistant to carb ice. After departing on a fairly mild day from the next airport over where my wife was doing t&g's we headed back to Potomac. It's only 5 miles or so, so she kept the power back. Right about the time she hit the pattern the engine started choking. She decided to head direct for the numbers and put it down (don't blame her). On roll out I got the idea to pull car heat and have her give me a little power. Sure enough, it cleared up. Carb Ice. If the conditions are right, you can always get ice.
steviedeviant
Pre-takeoff checklist
So after the plane was looked at and flown serveral times Sunday after they reviewed everything and after talking with the owner and mechanic, the conclusion has been that is was carb ice. they all admit that it is very rare for them to experience it, but with the moisture in the air that evening, it appears that is the only conclusion they can come up with.
Although I did apply carb heat, I believe that I didn't leave it on long enough as I was trouble shoooting. so lesson learned.
Needless to say, I have studied up more on this to make sure I understand it more for next time.
Still, scary experience for me but hopefully a learning lesson.
Thanks,
Stephen
Although I did apply carb heat, I believe that I didn't leave it on long enough as I was trouble shoooting. so lesson learned.
Needless to say, I have studied up more on this to make sure I understand it more for next time.
Still, scary experience for me but hopefully a learning lesson.
Thanks,
Stephen
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WannFly
Final Approach
Thanks for reporting back. good to know
BigBadLou
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Lou
True.
Though there is another option of the mag turning out of adjustment and working against the other mag and causing a drastic power drop, a possibly worsening condition. An in-flight mag check usually reveals a mag problem very quickly.
Stephen, thanks for posting back. Did the mechanics just "look" at the airplane or did anybody actually test-run it or even fly it? Big difference.
steviedeviant
Pre-takeoff checklist
True.
Though there is another option of the mag turning out of adjustment and working against the other mag and causing a drastic power drop, a possibly worsening condition. An in-flight mag check usually reveals a mag problem very quickly.
Stephen, thanks for posting back. Did the mechanics just "look" at the airplane or did anybody actually test-run it or even fly it? Big difference.
Ha. So thye reviewed it on the ground and once they determined it was safe to fly they took it up. I understand that it has flown three hours since Friday. Like getting a car fixed, never does what you want when you take it in.
PaulS
Touchdown! Greaser!
Carb ice is tough, especially if the engine starts running crappy before you apply. The heat in the muffler shroud dissipates quickly if the engine isn't running well, so carb heat needs to be put on and left on, especially if the engine gets worse when you apply it, if you landed with the carb heat off, you probably still had a lot of it in there.
I've never really had carb ice in an airplane, but I had a lot of it in my 73 charger that had a 318 v8. Took me a while to figure out the problem until one day I took off the air cleaner and looked down the carb while the carb was iced up. I was amazed at the amount of ice and frost in there. That engine had a port in the manifold that ran from exhaust manifold to exhaust manifold which kept the carb warm. That port was clogged with carbon, I pulled the manifold, cleaned the carbon out, and never had carb ice again. I'm pretty sure airplane engines don't have those hence the need for the pilot to pull carb heat. I just started flying again after a long lay off. Carb heat goes on every time in the pattern.
I've never really had carb ice in an airplane, but I had a lot of it in my 73 charger that had a 318 v8. Took me a while to figure out the problem until one day I took off the air cleaner and looked down the carb while the carb was iced up. I was amazed at the amount of ice and frost in there. That engine had a port in the manifold that ran from exhaust manifold to exhaust manifold which kept the carb warm. That port was clogged with carbon, I pulled the manifold, cleaned the carbon out, and never had carb ice again. I'm pretty sure airplane engines don't have those hence the need for the pilot to pull carb heat. I just started flying again after a long lay off. Carb heat goes on every time in the pattern.
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JM
Thanks for posting the outcome!
N659HB
En-Route
What's that mean?
I stand corrected. Glad they could determine an outcome. Safe flying!
ElPaso Pilot
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Dan Thomas
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Cars had that exhaust passage, but they also had a thermostatically-controlled carb air heating system to keep the induction air at around 70°F. Lots of guys took the stock air cleaner off and installed fancy chrome air cleaners for better breathing, but the stock unit that they threw away had the carb heat provision. Carb ice became a real hassle for many.
PaulS
Touchdown! Greaser!
My car was all stock, that that system consisted of a shroud around the manifold, a corrugated foiled tube and a vacuum operated valve on the intake of the air cleaner. That wasn't enough on cool wet days. It took me about 30 minutes to chisel through the carbon in that channel once I got the manifold off. I paid $600 for that car in 1983, it never let me down, but it was a beater.
ironnerd
Ejection Handle Pulled
Did you notice a drop in RPM when you applied Carb Heat?
(I'm a little embarrassed I didn't think of this earlier)
No doubt it was scary! The AA-1A I fly has a carb temp sensor, so I know if Carb Ice is a hazard.
Dan Thomas
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That carb air temp system can't solve everything. Its sensor is near the throttle butterfly, and as long as the throttle is open for takeoff or cruise, the pressure drop is primarily in the venturi, upstream of the butterfly. The temp in the venturi might be, and probably is, lower than indicated. And when you close the throttle, the pressure drop in the venturi falls off but the drop around the edges of the butterfly goes way up, and ice forms there. It's a big pressure drop, which is why ice is much more likely at lower throttle settings.
The METAR gives you temp and dewpoint. Pay attention to those numbers. Make a habit of it. When the difference between them is small, ice is far more likely.
nrpetersen
Line Up and Wait
To the OP - I wouldn't assume yet that your problem was carb heat/icing even though your mechanic etc has said so. The symptoms as you describe them in the first post don't all match carb ice.
ironnerd
Ejection Handle Pulled
The carb temp indicator is just a belt to go with my suspenders.
But I do appreciate the reminder to not get so wrapped up in gadgets that I forget to "Fly the [expletive deleted] airplane".
pigpenracing
En-Route
USE THE CARB HEAT ON EVERY LANDING!
I probably don't need the carb heat in my 172 but I use it on every single landing. It is there for a reason. Your manual says use carb heat as needed??? Well when its needed its probably to late to use it. Not fun when you are low and slow and the engine doesn't want to make power because the carb is frozen.
I probably don't need the carb heat in my 172 but I use it on every single landing. It is there for a reason. Your manual says use carb heat as needed??? Well when its needed its probably to late to use it. Not fun when you are low and slow and the engine doesn't want to make power because the carb is frozen.