Forced landing 11/06/11

[Zorro]

My first truly forced landing hopefully my last. in my Kitfox 4 1050 912ul. Was on cross wind runway 8 Pearson Field KVUO. Everything looked good for pre-flight and run up. I took off and when I turned cross wind,(900 feet) my RPM dropped and engine sputtered needle slogging around 3000- 3600 then down to 1500-2200 I immediately turned left toward runway looking over my shoulder, announcing to tower I was doing an emergency landing no one else was in pattern. I was high for 26 so I kept close and descended in my downwind keeping lots of options open. During the down wind it seamed to smooth out so I added full power and engine was coming back then did the same thing started to cough and sputter. When the time came I turned a base to final and wheel landed. Tower was happy said i did well A pilot friend was working on his ship and heard the engine quit, so he came running to see, said he saw the whole thing told me I did really well he has had 2 forced landings himself.
All I could think was I wanna fly now, darn it.
It's like everyone say's Everything gets clear and you see all your options open up in an instant. You just stay cool and sharp.
I can replicate this every time trying to trouble shoot, I have video of what happens, I don't know how to share the video here. would love any advice, I think it's the fuel pump.
I have 468 hours on the engine and have flown over 100 hours this year, new fuel filter and put another new one on yesterday, no joy! fuel is good hi grade stuff from an F.B.O.:eek:

I am glade that I have practiced this so many times, most of my landings I do as an engine out. Also I fly to train almost never am i dillying around up there. Constant improvement is the game in aviation.

[Zorro]

http://www.youtube.com/watch?v=ku7sEYc0Ces

video 1 what the engine is doing

runs ok at lowe rrpm but once I get up to 4600 or 5000 I go through the range of rpm ok , At 9min 20 seconds in video I go to high rpm then you see it drop off by it's self it looks like the throttle is pilled but it's just cutting out on it's own?
Any ideas?

video 2 of rpm wackiness

http://www.youtube.com/watch?v=1oLX8DQysCE

[Agfoxflyer]

Way to go. Been there done that. I had an off airport landing two years ago. I guess training paid off. I had probably one of my better landings! in a soybean field. Don't remember turning gas valve and switches off, but I did. I was at 1100 feet, so didn't have much time. One thing it taught me was pick your best landing spot and stick with it. Don't second guess during the event.

[DesertFox4]

fuel is good hi grade stuff from an F.B.O Is it 100 LL or auto fuel? Do you run any auto fuel?
Do you have any mil-spec black fuel lines in the aircraft? Those fuel lines were supplied with many kits years ago before they knew there was a concern. Still finding them in aircraft flying today. They are known for swelling on the inside causing fuel flow restriction with no apparent changes visible from the outside. Might be a reason you can run awhile at higher rpms then it drops off. Just one place to start your search for the cause. Good luck.

Congrats. on a successful landing.:)

[akflyer]

Hey mods, can you fix the title??? this landing is 4 days away from happening!

[Zorro]

your right it was last Sunday, I;m not planning on one next Sunday

[jtpitkin06]

From the comfort of my armchair and only two days past Monday I can only offer armchair advice. It's much better to be there in person but this will have to do.

It sounds like fuel starvation. So the first place I'd look is fuel flow. Take off the fuel supply lines and let the fuel flow into a bucket. See if the fuel flows freely for at least two gallons. A short squirt of a cup or two doesn't count. This will check if you have any problems as the header tank begins to drain. While you are doing the fuel flow testing, see if the header tank remains full. Any indication of header tank level dropping indicates you need to look at the fuel tank finger strainers. If you have any inline filters remove them and do the test again.

Next, look at the fuel pump. The spec for Rotax is about 5.7 psi. Excess pressure can cause flooding and the engine could falter the same as if pressure that is too low. There is a service letter on the Rotax fuel pumps. See if it applies to your pump.

That should get you started. Let us know what you find.

John Pitkin
Greenville, TX

[HighWing]

I think John nailed it. It sounds like exactly what happened to me once right after servicing the fuel system. I had just replaced all fuel lines forward of the firewall and an error on my part resulted in reduced fuel flow. It idled fine out to the run up area. Enough fuel in the bowls to sustain the run up, then as I taxied out for take off the bowls filled again, then after departure, I got to about 200 ft and rough running. Engine never quit and I was able to do a 180 and land. I would suspect that there is an issue with fuel flow introduced with yesterday's fuel filter change. My error was, I overtightened a fire sleeve clamp reducing the fuel flow to just above idle requirements.
Lowell

[Zorro]

Thanks, I did do some clamp tightening but it was on the coolant and oil system, every 20 hours they need to be checked. I'll look over the hoses today, it's painful to see the nice weather and be in a hanger.
I found this guy making pumps he claims are the last Rotax pump you will ever need to buy, Has anyone seen these or have any experience with them?

http://www.billetpump.com/home2/home.html


Fuel pumps and regulators for the Aviation Industry — The first "really new" mechanical fuel pump design in more than ten years engineered for the Rotax 912 and 914 engines.


Designed for carburetor, fuel injection, and turbocharger applications. Patented variable displacement design, only flows as much fuel as the engine requires. No diaphragm, valves, rocker arm, block plate, or gaskets. Hardcoated 6061–T6 billet aluminum housing with stainless steel internal parts. Design to be the last Rotax fuel pump you will have to purchase.

United States Patent Number 7,318,416

[Zorro]

I believe it's a 1994, aircraft is 1996, books are in hanger at the moment

[rogerh12]

Don't forget your vent lines. For fuel to flow out, air has to flow in somewhere.

Roger

[Zorro]

I put the video up on youtube you can see whats happening


http://www.youtube.com/watch?v=1oLX8DQysCE

in this second video you see it will run on low power settings, but around 9 min 15 sec. at high power it dropps and then really drops

http://www.youtube.com/watch?v=ku7sEYc0Ces

[Wheels]

I had an Identical power failure a few months ago. I replaced the entire fuel system. The carburators may have been the problem but finding a new fuel pump is the problem now. The one you mentioned wasn't in stock when I called the manufacturer. He no longer supplies a pressure regulator with it. He said to get one from a performance shop but I am having my old pump tested and if it tests good, I"ll use it until the manufacturer comes up with a replacement item.
Jack

[Dave S]

A couple additional tips on potential fuel restriction.

1) The "T" on the 1/4' line which splits the flow between two carburetors on the rotax can be a spot foreign material can hang up in. Any place a line goes onto a metal fitting may provide a place for material to hang up on.
2) When cutting in new fuel line or replacing fuel system parts - never assume the new line is free of bad stuff - good idea to cut the replacement line, then hit it with the air compressor and run sufficient fuel through it next to be sure it is clear before installing - look into the ends as far as is possible. Same with fuel pumps and filters - run fuel through them for a flush before hooking them up.
3) When you are all done - get a new gravity flow rate at the carbs - the data can be used for future comparisons as a quick test to see if the system is still flowing correctly.
4) When you are all done - get an operating pressure reading between the pump and carb with a temporary gauge if you don't have an installed gauge - again - this will provide data for future comparisons as a quick test to see if the system is still operating correctly.
5) Fuel systems can mess up in several ways - slow deterioration caused by swelling lines, clogging filter or a wearing pump can often be picked up during annual checks using 3) and 4) above - long before it becomes an operational issue.

It is amazing how close to zero fuel pressure can be with a high flow rate under full power on a carbureted system without causing a hic-up - but then it is right on the edge failure.

Sincerely,

Dave S

[catz631]

Jack ,
Check this out from Rotax-owner.com forums.The new pump from Rotax might solve your problem.Roger is a great guy and knows these engines !

"Hi all,
Just a quick note about the new Rotax fuel pump. The first production pumps did have a little issue at times with high fuel pressure and I understand it was from an issue at assembly and not the actual design. The newer production models don't have that issue. If you do happen to get one of the new fuel pumps that are too high in fuel pressure then send it back and they will be happy to replace it. You should always check the fuel pressure when installing a new pump and or an electric pump. Many have fuel pressure gauges in the cockpit and that works. If you don't then hook up a mechanical gauge and check the pressure at cruise rpm (i.e. 5000-5300 rpm) on the ground."

Roger Lee
LSRM-A & Rotax IRMT
Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell

[Zorro]

Ok I just got the new pump and it's different. pt# 893 110, it has a fuel overflow line and different size barbs on the inlet/outlet. Is their anything I need to do for this installation? Can I just adapt the hose to fit new barb?
To check the pressure (every one seams to agree I need to have a pressure reading) can I install a pressure gauge and read it from there?

[Zorro]

New fuel pump no joy, same trouble, good news I have 2 fuel pumps!
So I will start going through the whole thing, thanks for everyone's input Iv'e got plenty to look at.
Guess I will have to rent to get some flight time.

[Zorro]

pump was my best guess, I'm coming up with a plan. I don't want to replace my whole fuel system I want to find whats broke and fix that. It would be a waste to just rip everything out if it's not broken. I think first I'll go from gascolator to carbs looking for a clog. If nothing then my headder tank to on/off valve if not that change the lines from tanks to header. At that point I'll have changed the whole fuel system.
It started all at once, only happens after a minute of full power, and was flying great I fly almost every day 7 to 12 hours a week (building time to get a job). I took a week off and came beck to an emergency landing. Now Iv'e got ground sickness and need to fly.

[Zorro]

So the new pump didn't fix it, I started following the line back checked the Flow rate, it was really low with gravity feed.

gascolator was fine, then I got to the main fuel shut off, and I recalled that two weeks ago it got really easy to switch on and off. Prior it took pliers and I was planing on looking into it.

When I took it out, with my wing tanks inline valves off, the header tank drained just fine. The on/off main valve was missing a retention cir-clip, you could just pull the the thing right out of the valve body. I believe it was pulled out just enough to slightly retard fuel flow. After this the gravity feed is 1/6 a gallon in 15 min.
I will put it all back together on Monday and run it up to see what happens , crossing my fingers.

[jtpitkin06]

The flow rate of 1/6 gal in 15 minutes is inadequate. At take-off power the engine may consume over 10 gph or about one gallon in 6 minutes. You need at least that amount of flow in gravity feed. Preferably more.

Remember it is gravity feed that supplies the fuel pump. The pump supplies the carburetors.

If the pump doesn't get the supply it will cavitate or quickly drain the header and start sucking air.

Keep looking. You have something blocking your fuel.

JP

[szicree]

After this the gravity feed is 1/6 a gallon in 15 min.

That's only 2/3 gallons per hour! I drool faster than that when I'm sleeping. Something is plugged for sure.

[Zorro]

ahhh, I know its pathetic, going to keep going up the line, maybe slyfox will be right and I'll end up with all new fuel lines. BUMMER IT WAS NICE OUT TO. I might have to rent the citabria and do some lops and spins to vent my frustrations.
Thanks for all you input

[HighWing]

Just like my experience - enough flow to partially empty the carburetor bowls during run up and refill during taxi to the take off point, then emptying on full throttle climb out and having just enough fuel for rough running - mine ran at about 3500 RPM so easy to do a gentle return to the runway. I wouldn't be surprized if you already found the problem with the shut off valve malfinction. Good work. One more thought I had a Facet pump just down stream from the header tank with the on switch thumb distance away from the throttle. It went on immediately with the rough engine and likely helped a bit with fuel flow.
Lowell

[Zorro]

I found it at last, you folk were right on the track, flow was 8.75 gph at every point except 1, the hose exiting the gascolator, I saw that the hose didn't cover the whole barb, and the hose clamp (recently tightened) It closed over the top of the barb, This also caused the barb to cut into the hose, making a flap like check valve, the more fuel I demanded the harder it closed off the flow! So a 24 inch hose worth 8.50$ could have been a disaster.
Thank you every one I hope this thread contributes the grater good.

[Dorsal]

Happy Days, glad you found the problem.

[HighWing]

This is the second report of a "recently tightened" clamp issue. Mine makes three if you want to consider the firesleeve clamp. It makes me wonder about regularly checking the clamps and giving a little twist. It is exactly what happened in the first instance about ten years ago - give a twist every annual. I wonder if this is a good idea.
Lowell

[DesertFox4]

Thanks Zorro for the update on your fuel problem. Sometimes issues like yours take a methodical step by step approach to find.


It makes me wonder about regularly checking the clamps and giving a little twist. I wonder if this is a good idea.Lowell, I've done it also and for several years I've had to tell myself every conditional inspection not to mess with any hose clamps. If I'm actually replacing the hose due to a leak or deterioration then new clamps are used and an initial tightening with a follow up check a couple of flights later then I leave it alone if it ain't leaking.

As for flow testing: A fuel flow test is absolutely critical to execute before first flight. You have to know your engine will be receiving enough fuel to keep it operating at full throttle plus a good safety margin. I tested my system with the tail touching the ground as in a take-off/climb attitude. Mine being a tri-gear makes that fairly steep.

I would think a flow test would be a good practice also if ever you make changes to your fuel delivery system such as adding different type fuel filters , adding or removing components like gascolators or re-routing fuel lines, adding or removing secondary fuel pumps, fuel shutoff valves, changing header tanks ect. Last place you want to learn you have a reduced fuel flow issue is shortly after take off when many of your options have evaporated. Be safe out there guys.

[kitfox2009]

Great advice, Steve.

Cheers
Don

[Zorro]

well after testing the problem is still there. The fuel is flowing great. I had written a test flight plan, and never got past the full power run up.
27 seconds into the full power it did exactly the same thing.
I pulled the plugs the plugs and all 4 plugs on right side are black and carbon covered on the left they are perfect.

[szicree]

Perhaps fuel pump is overpowering right side carb float when you're at full throttle.

[jamesmil]

hi guys after looking at the pic,s of plugs i would say that the right side carb is very rich but the left side carb is running extremely lean to the point of fuel starvation. the ground strap is showing signs of discoloration from high heat and the porcelin insulator is clean. not as clean as we would see on a race engin after a clean cut but those plugs tell me to look at the float levels in both carbs.
it looks like the float is to low or there is trash in the needle and seat or trash in the high speed jet of the left carb.
i would also check the float leval on the right carb. hope this helps:)

[jtpitkin06]

Just a thought... have you tried bypassing the fuel pump and running on gravity feed alone? Without the pump it should run on the ground just fine. Do not fly it this way! This is for a test to see if the fuel pressure is too high and if the carb has any problems such as a float valve problem.
If it runs OK without the pump, look to the float valve.

If it still has a problem, reconnect the fuel pump and swap the carbs left to right to see if the problem follows.

You're going to find the problem, it's just a matter of eliminatiing everything step by step.

JP

[tahquitz]

I agree it looks like the left is running lean from the picture of the plug which can cause difficulty reaching/holding higher RPM. The main jet could be plugging with a bit of material, you could pull the jet and blow it out with a little compressed air or use a thin wire...be careful not to scrape the inside of the jet. Hope you find it soon.