Rotax 582 Running Issues... Help

[lburnard]

Hi guys,

I've recently acquired a Kitfox 4 and I cant get in the air any long than about 30mins without something going wrong. (makes it quite hard to get my tail wheel endorsement when I cant stay in the air long enough) Its a Rotax 582 Grey Head, approx. 350 hours and 15 years old... never been rebuilt.

Also keep in mind I'm in the northern end of Australia and our flying conditions here are very humid and hot (38°C) 400ft MSL (3000ft Density Alt)

1. First flight : the engine would start to drop RPM (500-1000) for no apparent reason at high RPM. Especially after about 15 secs of WOT. High EGT and high Water Temps. I figured it was a fuel issue, cleaned out all the tanks and fuel, changed the coolant to more water based mix and dropped the radiator 3" into the air stream. I also richened up the mixture one clip on the needle.


2. Second flight : This time I had good EGT temps, Coolant Temps are fantastic... but once again... on a go around at WOT... engine uncommanded drop of 500-1000 RPM only for a short time though. This time I think it might be the fuel pump, so I replaced the gaskets, I also worked out my needle setting should be back on the leaner side due to the higher Density altitude (and slightly dark plugs) and put it back to 1 clip leaner setting and also changed the main jet to one size smaller (leaner). I've also pulled the heads off and noticed my pistons are covered in big flaky bits of crud and the rings are stuck. So, I cleaned it and reassemble.

3. Third flight : I work out I shouldn't be taking off with the flaps in the spoiler position, the aircraft leaps into the air and everything is running great and I'm starting to have hope. There is also a noticeable increase in performance, yes it was doing 70kts!!!!.

After about 10 minutes of circling an abandoned airfield the engine starts to (or at least what I think it doing) misfire! Randomly every 1 or 2 seconds you can feel a kick/thud through the airframe, no drop in RPM. My instructor took over and we headed back to the airfield and by the time we had landed it had gone away.

I'm at wits end with this engine... my instructor won't get back in it with me until I get a new engine. Why would it be misfiring? Should I keep trying to extend the life of this thing, or just bin it?

Help.

[SkyPirate]

take the cowl off,..with tail tied..fire it up..have someone spray some WD 40 on the plug lead wires..if its got a dried out plug lead,,it can arch which will make it run rough etc..try to do it at a darker time of day so he will see if the wires are the cause,,he will see sparks jumping from the wire to the metal it's closest to

[Av8r3400]

At 15 years and 350 hours, it is far past the 5 year/300 hour TBO that Rotax has for this motor.

I would be suspect of all of the "soft" parts on the motor, especially in your climate. Crank seals, hoses, carb gaskets, plug wires all would be suspect at this point. With the humidity and lack of run time, I'd also be very concerned about crank and rod bearing corrosion.

Just my opinion...

[JimS]

That old of an engine you could be sucking air through the seals on the crank. Another thing to check would be the pulse line to the fuel pump (and the pump itself). Good luck!

[Olle1975]

Hi!

Which propeller did you use and which pitch do you set?
Very high pitch and high humidity could drop the rpm by 1000-1500 rpm.

Check all fuelfilters. If you have a fuelcounter, check it, there is a filter inside.

Check your fuelpump (underpressure), there is an membrane inside, all wires from and to the fuelpump MUST be leakproof.

My greyhead had a break of 10 years, now it's 15 years old. I revival it last year and checked pistons and rings. The last 25 hrs, it works perfect.

Olaf

[lburnard]

The prop is a 3 blade carbon fibre unit made by Bolly, it's pitched so my static rpm at WOT gives me roughly 6250 rpm. I don't run a fuel pump and the only filter in the system is the gascolator. I only run fresh 91 RON fuel which gets filtered through a chamois first and I always check for particles from the drain. I stick to Rotaxs engine running proceedures before flight, but everything just seems to happen in the air. I tried running the aircraft on the ground at WOT for about 4 minutes for about 5 runs and it seems to run fine.

As for the rpm drop, it only happed on touch and go's, about 50 ft agl, reducing the throttle a little seemed to stop the problem but I can't really say too much about it because as soon as it happened my instructor pulled the throttle to land, not testing how to fix the situation as his knowledge of engine operation isn't that great.

After my last flight I pulled the carbs fully apart and gave them a good clean out, I synced them the best I could at idle and 3000 rpm. The only thing I noticed is one of my set of floats in the carb bowl have lost some of their bouancy. I've yet to replace them.

I'm going to get my tailwheel endorsement and then I'll be able to test her out at my local airfield and see if I can replicate the problems, hopefully all the work I've done so far will fix the issue. If it still plays up and I don't crash into some tiger country I think it will be time for an overhaul.

One other note, it doesn't seem to consume much / if any injection oil and it's all set up correctly. Should there be a filter between the tank and engine, it seems to restrict the flow quite a bit.

[JimS]

I had a similar problem years ago. Take off was strong but about the time you were clearing the trees at the runway end the motor would start to sag. I have a backup electric fuel pump and the first time this happened the first engine failure item is to turn on the fuel pump. Viola, back to full power. Found I could consistently repeat the issue. Always full throttle with a nose high attitude. It would take about 15 seconds and I could watch the EGTs start to climb followed by the RPM sag. I pulled strainer screens, cleaned gascolator, rebuilt the fuel pump, pulled small pieces of rag through all of the gas lines, test flying each time to find the same problem. Finally removed the pulse line from the engine and found that the hose clamp holding it on the nipple coming off the engine had been slightly past the end of the nipple and was closing the diameter of the pulse line down. (Don't we all give those hose clamps just a slight turn at each condition inspection.) ID of the line was down to about 50%. Enough to run the engine at cruise power and even full power for just enough time to cause trouble. The backup electric fuel pump saved me the first time it happened. Of course this was the last thing I checked (when you find a solution it is usually the last thing you check).
Bottom line, watch the EGTs when your engine sags. If they are starting to climb right before, you probably have a fuel delivery issue.
Good Luck!

[Olle1975]

removed the pulse line from the engine

Do you mean the pneumatic wire whitch is mount from the engine to the fuel pump? Sry my english isn't the best.


I don't run a fuel pump

I've never seen a rotax eingine without a fuelpump. I suggest to mount a fuel pump, I think this is the only way to have a constant fuelpressure (must have between 0,2-0,5 bar) to the carbs.
During the start you need much fuel, I don't know if the fuellevel in the wingtanks deliver enough pressure for the fuellevel in the carbs.
It will be an explanation for this.....
As for the rpm drop, it only happed on touch and go's, about 50 ft agl, reducing the throttle a little seemed to stop the problem
I tried running the aircraft on the ground at WOT for about 4 minutes for about 5 runs and it seems to run fine

Olaf

[lburnard]

Sorry what I meant to say was, I don't run an electric fuel pump, although I do have one waiting to be installed.

I checked my pulse line, there is nothing visibly wrong with it.

The only other thing I have done to the mikuni fuel pump is change the gaskets and remounted it horizontally as stated from a few different sources.

[Av8r_Sed]

I'd suggest performing a fuel flow test per this FAA Advisory Circular:

http://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/media/ac90-89a.pdf

Also,

One other note, it doesn't seem to consume much / if any injection oil and it's all set up correctly. Should there be a filter between the tank and engine, it seems to restrict the flow quite a bit.

It should be consuming injection oil. Make sure the alignment marks are matched up between the injection pump arm and casting at low throttle. The arm should advance smoothly as the throttle is opened. You should have a filter between the injection oil tank and engine. It should be a stainless steel wire mesh type, not a paper or fiber element. This will prevent the filter blocking off if you get any water in the injection oil system.

[lburnard]

Thanks for that link, good info.

The oil filter looks like one of those paper types, so I'm not surprised it's restricting flow, I'll have to get it changed.

[Olle1975]

The marks must be matched, but I think this isn't the problem.
Check the fuelpressure between your fuelpump and carbs and you know if there is something wrong about your fuelflow.

Olaf

[JimS]

When you say you checked your pulse line and there is nothing VISIBLY wrong with it, did that include removing the pulse line and inspecting the "INSIDE" of the line or just looking at it as it is installed and calling it good?

JimS

[JimS]

Iburnard,
Have you made any progress with your engine problems?
JimS

[lburnard]

Hi Jim,

This weekend I'm travelling to another state to do my tail wheel endorsement, as soon as I get back I will take her down the airfield and give her a test run provided it stops raining.

And as far as the pulse line goes, I actually have some of that ridged line that CPS sells and its new, so there shouldn't be any dramas there.

I'm pretty sure the marks match on my oil injection system as well.

Before I take her on another run, I'll install the fuel pump as well...

So, Ill post back in about a week and a half on my progress.

[Olle1975]

Hi!


change the gaskets and remounted it horizontally as stated from a few different sources.

Horizontally is the right position but it's more important for fuelmixture like 1:50.

Do you have an instrument to read the fuel pressure, that will be my first step?

What about your EGT, is it balanced or did you see a difference?

If you have a camera, mount it in cockpit before your next start and record your flight. It's easier to evalute your temp., EGT, rpm after flight and you have the possibily to share it with us for locating the mistake.

Olaf

[lburnard]

Okay, I finally have my endorsements to fly the Kitfox, I've yet to return home though.

The aircraft I did my conversion on was the Australian Drifter ultralight with a new zero time 582 so I now have an understanding of how the 2-stoke engine normally runs and I also have a lot more confidence behind one.

I did notice a few things...

The oil filter on my engine is correct, but my oil injection system is setup incorrectly, while my marks do line up... they don't line up at the correct position! (lined up at closed throttle, as opposed the idle throttle position 3000rpm).

My engine runs smoother at a lower idle so i'm not particularly concerned with that. I know now where a stock 582s EGTs will sit, and I'm confident I have jetted mine appropriately for the conditions.


I will be running a electrical fuel pump.
I will be replacing my needle jet and jet needles. (never been replaced)
I will be replacing my floats. (one set had sunk)
I will replace the plugs and leads.
Last but not least, I will run a higher octane fuel (95RON) minimum.


I'll post more information after my test flight, I'll also get it on the GoPro so you guys might notice something I dont.

[Olle1975]

lined up at closed throttle, as opposed the idle throttle position 3000rpm

Your idle have to set by 2000 rpm and in this position your marks have to line up.

My engine runs smooth only up to 3000 rpm, under 3000 rpm it's shaky.

I recommend to check your fuelpressure between pump and carbs.

Olaf

[lburnard]

The CPS Part45 (manual dictates "around 3000 rpm")

The Rotax 582 Installation manual states "At throttle lever idle position the 2 marks must align" Operating Manual states idle speed is "ca. 2000 RPM"

But... one is IDLE POSITION and the other is IDLE SPEED. To me idle position is fully closed.

So, now there needs to be a definition of idle.. is it smooth idle @ 3000 rpm (CPS)... or is it rough idle @ 2000 rpm (Rotax). Or is it full idle / fully closed @ 1800 rpm.

My opinion would generally fall somewhere in between the two figures, if it smooth idles at 2500 rpm, then that's where I'll set it. Either way hopefully it starts lubricating my engine a bit better.

Idle idle idle...

[lburnard]

Well, took the Kitfox out to the field this morning and she ran like a dream...

Engine temps good, no missing, I was extremely pleased and I even took my missus for a fly and she was thrilled as well...

Until I was about 30 feet from my house with the aircraft on its trailer, and the rh wing security strut disconnected, the wing opened up into a power pole.

She is now a write off, and I was still in the process of insuring it.

Gone, What a **** week.

[Dorsal]

Sooo sorry to hear, the post started out so well :(

[SkyPirate]

That is the second time recently this has happened, sorry to hear about that, i had put many miles on my model 2 towing it backwards, luckily this never happened to me

[Av8r3400]

Aw, Man! That just stinks. Is there no salvaging the plane with a new wing? Did the impact take the plane off the trailer? Why is she a write off?

[lburnard]

The aircraft was dragged off of the trailer, the rh wing is missing most of its trailing edge, the aileron is a crumpled mess, propeller damaged.

I really don't know what to do with it now, maybe strip it for parts...

[ackselle]

Oh that sucks and blows....all at the same time!

[Pilot4Life]

lburnard,
Sorry to hear about your Fox! What a hit on a great day. Perhaps the consolation is that you DID FLY HER, and maybe that'll be a motivation to repair with another fuse and wing or finding another kit to finish! Keep us posted on what you decide...

[Geowitz]

Wow. I am really sorry for you. I tow to the airport every time I fly and always tell people, "the most risky part of it is the ride to the airport". Obviously, this doesn't help you now and I am by no means trying to make you feel worse, but if anyone else should see this it would help to keep this from happening to them.

I made up this simple strap from nylon strap and a backpack clip. Both available at typical craft stores. If my pins ever slip out the strap keeps everything together.

[Paul Z]

lburnard,
Sorry about your Fox!

Paul Zz

[SkyPirate]

I have seen worse case situations get fixed,..don't give up on her..you can fix it :)

[lburnard]

Skypirate, I think I will try to fix her, it's not going to be easy but it's better than putting her in the trash. We have the technology to rebuild her... and I suppose aircraft structures is my trade but I've never worked on anything like this before.

[SkyPirate]

I'm sure you will do a good job,..since you don't have any jigs,..cut and fit all your main structural pieces ,,use clamps, tack welded stanchions , spreaders ,etc to hold her true once your ready to start 100% welds pay mind to the welds pulling,..if you have to flash cool your welds ..(using a torch brush the heat across the weld to let it cool slowly) sometimes it eliminates pulling completely

[Olle1975]

Oh sry to see these pictures, but don't give up, I'm sure you do a good job to to fix this nice kitfox!!

Fingers crossed....

Olaf

[lburnard]

I've managed to strip the windshield and seat out, most of the frame has crumpled under the seat pan, but because the frame has been pulled down and my forward carry through spar is bent I'm not sure what original diamesions are to rebuild the frame and apparently skystar don't / won't release any drawings.

Can anybody help with diamesions of a simular frame? Tonight I will post some more pictures showing damage.

[lburnard]

This is probably the last post I will put under this section.

My major concern at the moment is, the airframe is bent so much that I'm going to find it hard to refit new structure without some sort of measurements to go by. I've figured I can cut the structure between the rear of the seat and just behind the control column, plus all the structure above the cockpit apart from the rear carry through spar.

+I've still got to work out what to do with the wing, I could probably manufacture aluminium ribs to replace the broken ones.

Its still a lot of work and I really can't believe this happened...

Thanks to everyone for the support.