520 turbo run rough on final

[Marshall]

I have a 1976 Cessna 206G 520 turbo. I have only about 30 hrs flying it, new plane for me.
I have new plugs and mags recently timed. When I am on final at 18 inches and lower just before push prop in , engine runs rough like it is over rich. I normaly run full rich on final, but I have tried leaning to 15 gal per hour. I have a JPI 930 . Any tips for how you have set up, or suggestions?

 

[Checkout_my_Six]

It may be too rich. Not uncommon to run a little lean and "not" go firewall full rich.

You'll want the ability to run more fuel on takeoff to keep the CHTs cool....

 

[mondtster]

I normaly run full rich on final, but I have tried leaning to 15 gal per hour.

What are the results of flying final with the mixture leaned?

The fuel injection setup may need some attention. Some systems seem more fussy than others, and some mechanics are better at setting the systems up than others.

 

[Clip4]

There could be several possibilities, but the fuel control unit calibration is where I would start because that is a maintenance item periodically required.

 

[Jim Carpenter]

As others suggested, try leaving the mixture somewhat leaned on final. At what altitudes are you operating?
I'd try leaving the mixture at whatever cruise setting it might be, all the way down final. Yes, you'll have another knob to push in if you have to go around, but no big deal. If that doesn't help, then more troubleshooting is in order.

 

[SloRoam]

I also fly behind the TSI 0520, and I was taught by an authority on Cessna 210's that while I'm in my descent, I actually will run the engine effectively extremely lean to keep CHT's high so the engine doesn't cool down as rapidly as it would if you just ran it rich during the descent.

This sets you up so that when you're in the pattern the engine is already become relatively cool, and the setting you'll find is already pre-leaned.

You will need to push in the mixture knob if you want to go around.

So now the question is how do you get it to the right mixture during the descent and when you're on final?

For that you should look at your turbine inlet temperature, and maybe try to keep it up around 14 or 1500, or whatever max temperature you can get it at when you're at 18 in.

If I were you, I would fly my final with the mixture just enriching a touch more than that, just in case you did forget to push in the mixture during a go around it gives you a few seconds to figure things out.

For a fuller description, try Chuck McGills 210 book, which covers TSI 0520 Cessna operations pretty well.

 

[mondtster]

I'd try leaving the mixture at whatever cruise setting it might be, all the way down final. Yes, you'll have another knob to push in if you have to go around, but no big deal.

That’s what I always do too, but I personally would still want to investigate the rough running to determine if something is really wrong with the engine or the fuel system setup.

 

[Tantalum]

engine runs rough like it is over rich

Have you tried to leaning it out a little?

 

[Clip4]

I also fly behind the TSI 0520, and I was taught by an authority on Cessna 210's that while I'm in my descent, I actually will run the engine effectively extremely lean to keep CHT's high so the engine doesn't cool down as rapidly as it would if you just ran it rich during the descent.

This sets you up so that when you're in the pattern the engine is already become relatively cool, and the setting you'll find is already pre-leaned.

You will need to push in the mixture knob if you want to go around.

So now the question is how do you get it to the right mixture during the descent and when you're on final?

For that you should look at your turbine inlet temperature, and maybe try to keep it up around 14 or 1500, or whatever max temperature you can get it at when you're at 18 in.

If I were you, I would fly my final with the mixture just enriching a touch more than that, just in case you did forget to push in the mixture during a go around it gives you a few seconds to figure things out.

For a fuller description, try Chuck McGills 210 book, which covers TSI 0520 Cessna operations pretty well.

extremely lean = burnt valves

 

[Checkout_my_Six]

extremely lean = burnt valves

now that right there is funny......

if it's that lean....the engine will quit and CHTs will be cool...cool...cool to the touch. Burning occurs when near peak EGT and high power settings.....or if something isn't working or setup properly.