• If You Are Having Trouble Logging In with Your Old Username and Password, Please use this Forgot Your Password link to get re-established.
  • Hey! Be sure to login or register!

Engine out

cub_driver

Registered User
Big Lake AK
I was flying this morning the weather was great it was 41 degrees and sunny. I had been in the air for less then a half hour when all of the sudden my enging started running rough matter of fact it felt like it quit running all together a couple of times. First thing I did was apply carb heat it didnt seem to help, then I switched fuel tanks I even pumped my throttle a couple of times. I started to turn the plane around to land on a road that was about a half mile behind me that was my only option other then putting my bird down in the woods. Let me tell you turning a airplane with the engine running then not running then running again is rather interesting. The engine started to run good well into my turn but I still flew over the road for a while. After I felt better about the engine I returned home the rest of the trip was uneventfull. Yes I was flying a little higher after that also.

If I had picked up carb ice I sure didnt have any indication of it before hand, it may have been carb ice I am just not convinced of it.. The low point drains where free of water when I checked them this morning and my run up was normal. There has been no work done to the engine I had just changed the oil and added a can of AVblend for the first time. I have 400 hours on this engine flying in all kinds of conditions and have never had it act like this. Anyone have any ideas of what else I should look over?

I just returned from my plane after taking another look at everything I am no expert when it comes to engines, I was not able to find a smoking gun.
 
Oh? don?t cha just hate these type of flights. Scares the baJesus out of ya when you?re flying, but then you can?t get it to do it again on the ground. Last time this happened to me, the IA swore that it was water in the fuel, but it turned out to be a 2 piece carburetor where the venturi would fall out of it?s holder, and then under the right differential pressure, it would suck its self back up where it belongs. Almost killed an instructor and student, but they made it back to the field (well almost, landed just a little short).
 
Could it be a stuck valve. Lycoming Service Bulletin 338B refers to sticking valves and gives the procedure for doing the wobble test. They recommend doing this every 400 hrs. I just got finished doing it on a Husky engine. I've seen them run fine on the ground and then get in the air and get hot and the engine starts running rough. We finally figured out the guides were to tight. Reamed them and never had it happen again.
 
Given the weather conditions here this morning, could've been water OR ice. Something to keep in mind if you think it's water in the gas, slowly pump the primer. If it runs......
SB
 
Up here in God's country, last night it rained, and this morning (at my place) it was 38* and NOAA weather said 97% humidity. Lot's of termination dust, too. (Snow on the mountains.) Perfect conditions for either water or ice.
SB
 
I guess it?s time to start talking about water/ice and such. 36f here this morning.

Wanted to order the Niagara oil cooler but bought the Reiff engine heater instead. Where did summer go?
 
I will be flying again in the morning you can bet I will be draining more fuel out of those low point drains.

Cub_Driver
 
Don't forget to pull the plug on the carb float bowl and drain that. Also pull the finger screen at the carb inlet and give it a close look. If is was H2O, you should find some still in the float bowl. Check all this along with the fuel bowl and screen.

If you can't find any dirt or water anywhere, it would be wise to have a experienced mechanic check the engine over, it could be anything. Better to play it safe than just blame carb ice.
 
Also, go down to the auto parts store, and buy some of the small red plastic cans of ISO HEET. DO NOT buy the yellow cans of HEET.

The ISO HEET product is, by the manufacturer's claim, over 96 % Iso Propyl alchohol, which is a legal additive for aircraft piston engines for anti icing in fuel systems.

I put a can of ISO HEET in each wing tank occasionally during winter. This stuff will help to "find" the water in the fuel system (it essentially gloms onto water droplets, and coalesces them into larger drops), as well as keeping it from freezing in the tanks, gascolators, etc.

The FAA will never tell you that ISO HEET is a legal additive, only that any additive for aircraft piston engines must be pure iso propyl alchohol. I've bought research grade Iso Propyl from the chemical suppliers, and they only claim 96 %, so if you believe HEET's claim, it should work fine. My experience is that it has for a number of years.

I like the stuff, cause it is conveniently packaged, sealed to prevent absorbing water (which is its purpose, and it does with a vengeance, from the atmosphere, once exposed) and easily dispensed, while fueling.

Make sure it's mixed properly, and understand that the manufacturers say "up to" 1 % by volume of fuel may be added. That's a lot, but.....

I use one of the small red cans per tank any time I fill up initially, and perhaps half a can per tank when re-fueling.

Don't use the yellow can HEET. It contains methanol, which can attack numerous rubber parts in your fuel system, and is not approved for aircraft piston engines.

Pour a couple cans of this stuff in the tanks, rattle the thing around, sump the hey out of it, and go fly.

Mike V
 
Just had a 160 hp PA-12 do that here. The engine started to run really rough and the pilot pulled on carb heat. That killed the engine and he landed in a field. A local mechanic inspected it for water or split carb then fired it up again. Same problem. Took the carb off and found the problem was a stuck float. How rare is that? If he had leaned it way out instead of applying carb heat he probably could have made the runway at Hackensack but he was thinking ice instead.

Brad
 
annestoy said:
How does leaning an engine help a stuck float?

Anne.

Stuck float leaves the float valve full open... More fuel enters the bowl than is consumed, creating an extreme rich situation...
 
Stuck Float Valve

The stuck float valve is familiar....had that happen a couple of times in the Cub before we diagnosed it. Thought it was carb ice given prevailing conditions at the time. Well, one day it bogged right out at 50 ft, half way down the air strip with about 500 feet left. I slipped sideways and landed. It wouldn't run up and ran rough. We took the cowl off and a mechanic friend tapped the carb with a wrench--presto! Replaced the valve seating and cured that and I learned a lot about the carb when I rebuilt it....
 
almost quit

Had happen to me once was a dirt dobbers nest in muffler, second time baffling came loose in muffler and got the same results. A buddy had same problem with a piece of foam off foam covered air cleaner plugged carb. I guess there could be a number of things so check carefully it might not be carb ice let me kow for my own good what you find.
 
Just replaced the float and valve seat on my sons cessna 150 this weekend. On final ,RPM dropped about 300 , unexpectedly . He landed with fuel running from the carb heat box . replaced the parts [cheep fix] and it flies like new. Rick :lol:
 
I hate to admit it but I think I had a bad case of carb ice. I have had it many times in the past but never this fast and never this extream. Flying in Alaska you just learn to keep a eye out for it. That is what has me baffled I never seen a drop in RPMs untill my engine quiet, when I looked at the tach I was still turning 2490 RPMs and falling I cruise at 2500 RPMs. I guess carb ice can be a real sniper.

I have flow my plane the last two days it has run like a well oiled clock.

Cub_Driver
 
I hate to admit it but I think I had a bad case of carb ice. I have had it many times in the past but never this fast and never this extream. Flying in Alaska you just learn to keep a eye out for it. That is what has me baffled I never seen a drop in RPMs untill my engine quiet, when I looked at the tach I was still turning 2490 RPMs and falling I cruise at 2500 RPMs. I guess carb ice can be a real sniper.

I have flow my plane the last two days it has run like a well oiled clock. Thanks to every buddy that has taken the time to suggest possible causes.

Cub_Driver
 
Carb Ice

Everyone has probably already seen the carb icing probability chart published by Transport Canada (I think), but for those that haven't, here it is.

Carb Icing Chart

Jim
 
Nice chart, thanks. From the URL, it looks like it was published by EAA Chapter 1094. Wonder how they came up with it?

Anne.
 
Carb Ice Chart

Anne,
I happen to be the webmaster for EAA 1094 and instead of bugging Steve when I want to post a picture or something like this chart, I just make a page off of the chapter web site and put it up for all to see. I downloaded the chart from a Transport Canada link somewhere, but I can't find the actual reference to credit the proper authority. I went ahead and put it up without being able to cite the source because I feel that this is a safety item that needs to be shared. I live in N E Texas, and according to this chart, it is unbelievable how often the weather conditions are conducive to carb ice.
Another page that I recently made was a photo gallery for Will's J-3 Cub site from the Bartlesville Fly-In last weekend.

Bartlesville Cubs 2003

Jim
 
I found that chart in the book "from the ground up"The chart is a bit smaller and in black and white, page 54. From the ground up, is published by aviation publishers, Ottawa Canada and is the 26' revised edition. This book is kind of the learning bible for pilots up here. Lots of good stuff.
J.C.
 
Back
Top