My 1st aviation hiccup

ahmad

ahmad

Pre-takeoff checklist
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Apr 9, 2017
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Midwest Aviator
Just hit 480 hrs.

150 NM leg. Flying vfr at 3500 ft under a layer at 4500. 75 miles into it the winds started picking up. I noticed that my rpm dropped to 2300. I get it back to 2400. a min later it is at 2300 again. ok adjust it back to 2400. Soon it drops to 2200. I push the throttle in more and notice I'm at full throttle now but still getting 2300 (usually get 2700). So, I knew something was wrong. I called center and said I am diverting to DEC 14 NM to my left because I am losing my engine. She says ok radar services terminated. Contact DEC tower. I ask her for the tower freq then switch to tower. At this point I am trimmed for best glide and getting a good vibration from the engine and rpm has dropped to 2000 and I couldn't maintain altitude. Called the tower and report 13 miles out. he says ok but you aren't declaring emergency? I responded I am and that I also won't make the field. Told them I was putting it down in the fields under me. my gauges all in the green. everything looks good but no power. I am scratching my head as to what's happening. then my ppl material rushes to my head. loss of rpm. rough running engine. it's carb ice you idiot. I am at 2000 agl and heading for the field when I turned the carb heat on. 15 secs later got full power and climbed. Headed back towards DEC just in case but by the time I got there all felt fine so I continued on.

I feel a bit stupid and think carb ice should have been my 1st thought. I pulled the checklist out after trimming for best glide but I was looking for trouble shooting partial power. so, I completely overlooked the loss of engine during flight and started to figure it out in my head thinking the checklist isn't helping me. confirmation bias?

This was another lesson learned.
 
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First, if this was you first experience with carb ice in cruise, don’t beat yourself up too bad. When faced with an unknown partial loss of power you did the aviate, navigate, communicate thing and made sound decisions.

This experience will now be seared into your brain the next time you have a partial loss of power.
 
Thanks for sharing. That was exciting.

As I was reading, I was thinking you bought a plane with a bum engine…glad you’re safe and wallet intact.

Were you calm, panicked, or something in between?
 
Thanks for that story and reminder about carb ice. I’ve only had that happen once, and it does tend to get your attention.
 
Carb ice can be a little insidious if you aren't expecting it. My first experience with it in cruise I had a more experienced pilot riding in the right seat. He picked up on the indicators before I even noticed anything different. Loss of manifold pressure, increase in CHT, slight stumble to engine.
 
That’s why a good memory checklist is something you should learn early on.

My first instructor liked ABCFAST:

A - Airspeed / trim for best glide
B - Best landing spot selected (don’t waste a lot or time)
C - Checklist / FAST
F - Fuel
A - Air / Carb Heat
S - Spark / Squawk / Starter
T - Troubleshoot / Talk

I still have that memorized 20 years later.

If you use something like that you should be pulling the carb heat 10 seconds or less (hopefully much less) into the problem.
 
Whew... glad you got it figured out before you were on the ground. Good job on that part. I've never experienced carb ice, but I only have about 35 hours in a cessna.

It is hard to pull out a checklist in an emergency. I had a magneto intermittently failing a couple years ago and ended up declaring and diverting. The FSDO called later and one of the questions the ASI asked was if used a checklist. It was then I realized I hadn't. I did the "fuel, air, spark" thing in my head, and spent a lot of time thinking through the issue, but didn't actually pull out the written "loss of power" checklist.

FWIW, you might get a call from the FSDO. The one I described above felt a little confrontational on the phone, and she asked me to send her some records on myself and the plane, but after that, nothing came of it. She was very pleasant in the second and final call. The call I got after my second forced landing was very short and informal. He did go look at the plane, but never requested any info from me.
 
This is sort of related, I was heading to KSAC from KLLR and descending from the geyser mountains, I had this loss of power that progressively got worse, and I thought I wasn't going to make it. I started to line up for a nearby non towered airport, went through the checklist, and wa lah, I was too lean!

It was a hot day, and I normally cruise at LOP. I guess it could have been a cold day with the same result. This was an Arrow II with an IO 360 that obviously has no sort of carburetor altitude compensation, so naturally it leaned out on descent. I hadn't been flying the plane long, and most of my time prior to that was in a Turbo Arrow, where high altitude descents (and climbs) generally don't result in significant mixture changes.
 
Honestly I was as calm as this moment writing about it. Panic and freaking out does nothing but make the situation worst. The ironic part was the fact that 5 mins prior to this I was thinking man this plane has been actually pretty nice. I like it. I have not had any major issues. When I realized I had an issue I went to action and was more annoyed than nervous or anything. After landing I noticed that the humidity was at 65% and the temps at my altitude was at 1C. I have gone over the emergency checklist a bunch of times and usually look at it every time I fly. In this instance I was looking for partial power loss in the checklist. It wasnt there so I moved on to what could it be. My 1st thought was loss of oil pressure. Nope that looks good. Then I thought water condensation in the fuel(I had strained fuel but still thought this). Not much I can do about that. Next I thought I hope its not a busted cylinder head. Not much I can do about that. Checked the mixture and primer and verified both were good. Then the loss of rpm and rough running engine from the ppl studies came to mind and I knew exactly what was going on then. Turned the carb heat on and saw a slight drop in RPM which I expected. For the next 10 secs I was expecting full power and if that didnt happen I was committed to the field in front of me. That vrooom RPM increase sounded awesome to my ears.
 
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Mother nature almost gave you the lesson after the event (which didn't happen....the Landout). But she relented :) and you prevailed.
(At least in a 150 you likely didn't freak out the family....(!))
 
Thanks for Sharing. Can be easy to just learn the lesson and move on and not admit your mistake.

Took a friend of mine 3 years to admit he flew his glider one afternoon and after landing reached in his pocket and found the main pin for the horizontal stabilizer still in his pocket. He had forgot to install it during assembly, and didn't catch it on the preflight.
He had flown for 3+ hours with only some electrical tape and aerodynamic pressures holding the horizontal stabilizer on the glider. I couldn't find it, but have seen a video of a glider losing it's horizontal stabilizer during the takeoff roll when the pilot failed to install the main pin.

Your event should be a reminder for all of use to practice (when able) and review our emergency procedures frequently, Not just every two years during your flight review.
If you fly infrequently, probably should review and practice at least one emergency procedure every flight.
If flying regularly, probably twice a month is a good plan.

I have had Solo Students have carb ice on their 2nd or 3rd solo flight. Which is why I make all my student practice power loss procedures prior to solo. They won't solo until they consistently turn on the Carb heat and check the fuel selector and/or fuel pump, when I simulate a power loss.

Brian
CFIIG/ASEL
 
brcase said:
Thanks for Sharing. Can be easy to just learn the lesson and move on and not admit your mistake.

Took a friend of mine 3 years to admit he flew his glider one afternoon and after landing reached in his pocket and found the main pin for the horizontal stabilizer still in his pocket. He had forgot to install it during assembly, and didn't catch it on the preflight.
He had flown for 3+ hours with only some electrical tape and aerodynamic pressures holding the horizontal stabilizer on the glider. I couldn't find it, but have seen a video of a glider losing it's horizontal stabilizer during the takeoff roll when the pilot failed to install the main pin.

Your event should be a reminder for all of use to practice (when able) and review our emergency procedures frequently, Not just every two years during your flight review.
If you fly infrequently, probably should review and practice at least one emergency procedure every flight.
If flying regularly, probably twice a month is a good plan.

I have had Solo Students have carb ice on their 2nd or 3rd solo flight. Which is why I make all my student practice power loss procedures prior to solo. They won't solo until they consistently turn on the Carb heat and check the fuel selector and/or fuel pump, when I simulate a power loss. The Muscle memory of at least touching each control is important when practicing procedures.

Brian
CFIIG/ASEL
Click to expand...
 
You won't make that mistake again. I bet it ran really crappy right after putting the carb heat in. Good job getting it done.
 
RyanShort1 said:
That’s why a good memory checklist is something you should learn early on.

My first instructor liked ABCFAST:

A - Airspeed / trim for best glide
B - Best landing spot selected (don’t waste a lot or time)
C - Checklist / FAST
F - Fuel
A - Air / Carb Heat
S - Spark / Squawk / Starter
T - Troubleshoot / Talk
Click to expand...

I like this. I'm going to shamelessly start using this.
 
PaulS said:
You won't make that mistake again. I bet it ran really crappy right after putting the carb heat in. Good job getting it done.
Click to expand...
Never. It did run rougher with more drop in RPM which actually sounded good to me because I was expecting that.
Nothing teaches more than experience. One of my professors back in the day would let us screw up then laugh and say "That'll learn him". ha
 
That airframe is particularly susceptible to carburetor icing. On the takeoff roll I like to apply full carb heat and full throttle...........then in a couple of seconds push the carb heat back in. Here is my 150J on the beach!

1702399320699.png
 
ahmad said:
Just hit 480 hrs.

150 NM leg. Flying vfr at 3500 ft under a layer at 4500. 75 miles into it the winds started picking up. I noticed that my rpm dropped to 2300. I get it back to 2400. a min later it is at 2300 again. ok adjust it back to 2400. Soon it drops to 2200. I push the throttle in more and notice I'm at full throttle now but still getting 2300 (usually get 2700). So, I knew something was wrong. I called center and said I am diverting to DEC 14 NM to my left because I am losing my engine. She says ok radar services terminated. Contact DEC tower. I ask her for the tower freq then switch to tower. At this point I am trimmed for best glide and getting a good vibration from the engine and rpm has dropped to 2000 and I couldn't maintain altitude. Called the tower and report 13 miles out. he says ok but you aren't declaring emergency? I responded I am and that I also won't make the field. Told them I was putting it down in the fields under me. my gauges all in the green. everything looks good but no power. I am scratching my head as to what's happening. then my ppl material rushes to my head. loss of rpm. rough running engine. it's carb ice you idiot. I am at 2000 agl and heading for the field when I turned the carb heat on. 15 secs later got full power and climbed. Headed back towards DEC just in case but by the time I got there all felt fine so I continued on.

I feel a bit stupid and think carb ice should have been my 1st thought. I pulled the checklist out after trimming for best glide but I was looking for trouble shooting partial power. so, I completely overlooked the loss of engine during flight and started to figure it out in my head thinking the checklist isn't helping me. confirmation bias?

This was another lesson learned.
Click to expand...
Congratulations on resolving the challenge in a timely way.

In my opinion it is best to declare an emergency at the first sign of trouble so ATC can use all the tools they have to help you.
 
Had carb ice in cruise on my first XC flight after getting my PPL. Also in a C150. Had wife and dog on board. Similar experience, turned to nearest airfield, lost some altitude, figured it out while troubleshooting. Wife has not liked flying with me since that day 30 years ago.

Good job, glad it turned out fine.
 
brcase said:
Took a friend of mine 3 years to admit he flew his glider one afternoon and after landing reached in his pocket and found the main pin for the horizontal stabilizer still in his pocket. He had forgot to install it during assembly, and didn't catch it on the preflight.
He had flown for 3+ hours with only some electrical tape and aerodynamic pressures holding the horizontal stabilizer on the glider. I couldn't find it, but have seen a video of a glider losing it's horizontal stabilizer during the takeoff roll when the pilot failed to install the main pin.
Click to expand...

OMG! That's a terrifying story!
 
Ed Haywood said:
Had carb ice in cruise on my first XC flight after getting my PPL. Also in a C150. Had wife and dog on board. Similar experience, turned to nearest airfield, lost some altitude, figured it out while troubleshooting. Wife has not liked flying with me since that day 30 years ago.

Good job, glad it turned out fine.
Click to expand...
haha.
I told my wife this and she said she wouldn't have been nervous. Nothing honestly phases her. She's the calm one in the family and she also trusts me more than I do. I am glad I was solo. It probably made it easier for me to deal with the situation instead of having to now worry about passengers.
 
RyanShort1 said:
That’s why a good memory checklist is something you should learn early on.

My first instructor liked ABCFAST:

A - Airspeed / trim for best glide
B - Best landing spot selected (don’t waste a lot or time)
C - Checklist / FAST
F - Fuel
A - Air / Carb Heat
S - Spark / Squawk / Starter
T - Troubleshoot / Talk

I still have that memorized 20 years later.

If you use something like that you should be pulling the carb heat 10 seconds or less (hopefully much less) into the problem.
Click to expand...
When I instructed in a 150, I taught Carb Heat was WHILE setting up best glide.

Reason being, if you have a total failure, if you wait, there will be no heat left in the system to deal with any ice, so get it on early. And you can do so while pulling back on the yoke.
 
Pinecone said:
When I instructed in a 150, I taught Carb Heat was WHILE setting up best glide.

Reason being, if you have a total failure, if you wait, there will be no heat left in the system to deal with any ice, so get it on early. And you can do so while pulling back on the yoke.
Click to expand...
I don’t see a problem with that, but the mnemonic is a way to make sure you don’t miss it. It’s easy to miss something under stress.
 
RyanShort1 said:
I don’t see a problem with that, but the mnemonic is a way to make sure you don’t miss it. It’s easy to miss something under stress.
Click to expand...
Kind of like when I started flying complex aircraft, shouting BGUMPS BGUMPS BGUMPS from downwind to touchdown.
 
I've always known those planes to be ice-monsters. Congratulations on sound decision making and a calm, prompt response.

Life gives us the test sometimes before we get all the lessons.
 
While reading the OP I was suspecting that carb ice was the cause ...

Good work pilot!
 
This sort of thing is mostly the fault of the flight school. Carb ice is poorly understood, and many pilots think it's just a wintertime thing. The physics of carb ice are not being taught in ground school or in flight training, and because it's hard to simulate, it doesn't get covered.

As the air flows through the carburetor, it accelerates though the venturi. Accelerating air reduces its pressure, which reduces its temperature. The pressure drop is necessary to suck the fuel from the nozzle, which is why the venturi is there. The fuel being sprayed into the venturi consumes heat from the air as it evaporates, lowering the temperature even more. Soon the temperature gets down to the dewpoint, and moisture begins to collect and freeze in that carb and on the throttle plate, choking off the airflow. One can get as much as a 70°F temp drop in that carb, all the way from an ambient temp of 100°F to 30°F, below freezing. It sure ain't just a wintertime thing.

Now, the OP was flying 1000 feet below an overcast. The temperature drop with altitude averages 2°C per thousand feet, and the cloud represents temperature and dewpoint being the same, so he was only 2°C from the dewpoint, and the OAT was 2°C higher. A carb ice chart, in degrees C:

1702487864680.png


Pick a temperature, such as 10°C along the bottom axis, the temp axis, and run up that line to about 8°C and see where the intersection is. It's right in the middle of the worst possible place for ice.

Here's a current METAR for Vancouver, BC.

1702488220315.png

Temps and dewpoints in the red squares. This is the sort of thing a pilot MUST check before taking off, and understanding what those two numbers are telling him. Even if their spread is larger, that temp will fall as you climb while the dewpoint will remain the same, and they get close, like the two-degree spread 1000 feet below the cloud deck. In Vancouver at this time, the clouds are high, reflecting the likelihood of overrunning warm air. It doesn't mean that the carb ice risk isn't there near the ground.

Understanding carb ice, and indeed basic meteorology, is critical to survival.
 
I wonder how much time the OP had left before there wasn't enough heat to melt and eat the ice.

The carb eating the ice is also a pretty undesirable sound.

Very glad you figured it out!!!
 
Only time I ever got carb ice was in a Conti powered 152 during training, never since ...
 
Dan Thomas said:
This sort of thing is mostly the fault of the flight school. Carb ice is poorly understood, and many pilots think it's just a wintertime thing. The physics of carb ice are not being taught in ground school or in flight training, and because it's hard to simulate, it doesn't get covered.
Click to expand...

I took a printed chart just like that to my CFI during private training to discuss it, as it had never been mentioned.
He was completely disinterested in it or talking about it.
 
Skyrys62 said:
I took a printed chart just like that to my CFI during private training to discuss it, as it had never been mentioned.
He was completely disinterested in it or talking about it.
Click to expand...
Because he knew nothing about it, and didn't want that to show.
 
Dan Thomas said:
This sort of thing is mostly the fault of the flight school. Carb ice is poorly understood, and many pilots think it's just a wintertime thing. The physics of carb ice are not being taught in ground school or in flight training, and because it's hard to simulate, it doesn't get covered.

As the air flows through the carburetor, it accelerates though the venturi. Accelerating air reduces its pressure, which reduces its temperature. The pressure drop is necessary to suck the fuel from the nozzle, which is why the venturi is there. The fuel being sprayed into the venturi consumes heat from the air as it evaporates, lowering the temperature even more. Soon the temperature gets down to the dewpoint, and moisture begins to collect and freeze in that carb and on the throttle plate, choking off the airflow. One can get as much as a 70°F temp drop in that carb, all the way from an ambient temp of 100°F to 30°F, below freezing. It sure ain't just a wintertime thing.

Now, the OP was flying 1000 feet below an overcast. The temperature drop with altitude averages 2°C per thousand feet, and the cloud represents temperature and dewpoint being the same, so he was only 2°C from the dewpoint, and the OAT was 2°C higher. A carb ice chart, in degrees C:

View attachment 123235

Pick a temperature, such as 10°C along the bottom axis, the temp axis, and run up that line to about 8°C and see where the intersection is. It's right in the middle of the worst possible place for ice.

Here's a current METAR for Vancouver, BC.

View attachment 123236
Temps and dewpoints in the red squares. This is the sort of thing a pilot MUST check before taking off, and understanding what those two numbers are telling him. Even if their spread is larger, that temp will fall as you climb while the dewpoint will remain the same, and they get close, like the two-degree spread 1000 feet below the cloud deck. In Vancouver at this time, the clouds are high, reflecting the likelihood of overrunning warm air. It doesn't mean that the carb ice risk isn't there near the ground.

Understanding carb ice, and indeed basic meteorology, is critical to survival.
Click to expand...
The first time I ever encountered the venturi icing effect was draining an air compressor under pressure. Open the valve to drain all the air out to service it. After a couple minutes the whole valve was iced over and air had all but stopped flowing despite plenty of pressure in the tank.
 
Racerx said:
The first time I ever encountered the venturi icing effect was draining an air compressor under pressure. Open the valve to drain all the air out to service it. After a couple minutes the whole valve was iced over and air had all but stopped flowing despite plenty of pressure in the tank.
Click to expand...
That's very common. The pressure drop as the air leaves the tank does it.
 
Racerx said:
The first time I ever encountered the venturi icing effect was draining an air compressor under pressure. Open the valve to drain all the air out to service it. After a couple minutes the whole valve was iced over and air had all but stopped flowing despite plenty of pressure in the tank.
Click to expand...
I have an old Wisconsin engine on a trencher that will make ice on a hot, humid summer day. You can see ice forming on the outside of the carb. I assume it's building ice inside as well, but it doesn't seem to be enough to effect the performance (such as it is for a 50 year old single cylinder engine). Kind of cool to actually see it happening though. I've seen other carburetors sweat before, but that's the only one I've seen make ice.
 
Dan Thomas said:
That's very common. The pressure drop as the air leaves the tank does it.
Click to expand...
This was well before I knew the what and why of what happened. Was probably 15. But that moment always stuck.

If only they taught stuff like this in high school, I might not have slept through it.
 
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