OS 50SX Hyper Gone Crazy.

[chuckjones]

Hello -

I'm on my 3rd Gallon of fuel, I do forward flight, mostly around 70% throttle, learning rolls and stall turns.... basic stuff.

About 5 flights ago, I had a crash, which visible bent a couple of the head fins back - and cracked the first one. Since then it hasn't sounded the same. A little noisier. Hard to describe how so, a little more cracky and unmuffled?

Last flight, I was doing some nice stall turns, closer to 100% throttle. At some point, maybe 1/4 tank left, it started to die when I gave it more throttle, instead of powering up. I landed it, can smell it's burning something. I let if cool down, and waited a couple hours.

Then it wouldn't start.

I changed the glow plug today, it was clearly dead. Odd that it would replacement this quick, but think that's symptomatic of the "real" issue".

It started up fine with the new plug. Let it hover at 65% for about 2 minutes, and then it starts to rev really high. I throw the throttle cut switch, but it still is running, sounds completely different now. I had to pinch the line to get it to stop running.

Smells crappy again, and there are some visible signs of problems. What the heck is this about? The photos show the "black" stuff leaking. Scared now.

[Ah Clem]

The black stuff is usually aluminum particles in suspension in the fuel oil.

You said the fins were damanged. Any chance the head itself is loose or cracked.

Look for the obvious when looking for the source of the erratic running and the black stuff: leaking fuel lines (in tank or external, allowing air to enter), plugged carb, loose carb, loose backplate, loose muffler, loose mounting bolts, etc.

[chuckjones]

Ok,

You were correct, the muffler was loose, the paper gasket was gone.

It ran fine.

For 5 minutes, and then the same original problem came back. It started to stall when I gave it throttle, from about 75% to 100%.

I thought it was me, until it stalled a good 100 feet in the air, and had to do an emergency auto that I landed in some brush that just resulted in a broken tail boom.

Someone at the field suggested it may have been too lean (a plane guy), but I've never adjusted the needle valve, in fact the manual says you probably don't have to. And there is always a real steady stream of thick white smoke coming out.

Any ideas for this new? Sorry, I'm used to - and prefer electrics for a reason.

[Laurens]

Souns like you're running a too high headspeed and running lean. When you feel the underside of the crankcase you should be able to touch it for five seconds.

[Ah Clem]

I agree with Laurens about the mixture being lean.

"but I've never adjusted the needle valve, in fact the manual says you probably don't have to"

The needle valves need to be adjusted both initially, and occasionally, depending on conditions If it is a particularly cold, dry morning, the motor will tend to run lean. Hot and muggy, it will run rich.

OS motors are pretty easy to set, but you do need to get used to doing it (i.e. what it sounds like when it is lean vs. rich, etc.). Smoke is a reasonably good indicator, but unless you are used to knowing how much smoke is appropriate for a specific fuel, etc. it is not the be all and end all).

Without being able to see it and hear it, it is hard to diagnose. It may be running erratically due to an air leak, the damaged head etc.

Is there anyone local who can assist you?

[phantom1500]

it is leaning out from air getting in some how, with bent and cracked barrel fins it might have warped the barrel to head mating surface, if you have a true straight edge you can check both the barrel and head when seperated? or sit it on glass to see if it sits dead flat with out rocking?