Cessna T-206 w IO-520T

Dave Anderson

Dave Anderson

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So we are running the 206 and it’s 30 degrees here in PA/MD. In takeoff with mixture full rich we are getting the engine bogging down a bit at about 300’ and losing a bit of power The fuel pressure is like 29 psi and burn is mid-20’s

Does the mixture in these engines need slightly leaned in this colder denser air?

What are others SOPs when it comes to cold flying them?
 
Sounds like its running out of fuel to me (lean die out), like it needs more.
 
More dense air needs more fuel to keep mixture % the same. That's why on normally aspirated engines, it is leaned to best power at higher density altitudes.

So at lower density it would need more fuel for best power. Now I don't know on a turbocharged engine what the temperature rise is between turbocharger and engine inlet, but it can be quite high depending on configuration.

There should be a chart for setting fuel flow for OAT and MP and rpm.
 
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so do people lean out like 1/4” on takeoff because of the colder dense air ? I think density altitude was like -1200

This seems backwards I feel like you should only lean when it’s a high density altitude >5000 lets say

It’s a fuel injected Turbo it only had done it a fee times
 
Dave Anderson said:
so do people lean out like 1/4” on takeoff because of the colder dense air ? I think density altitude was like -1200
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That's the wrong way. You want it richer.

I assume you meant the TSIO-520-T (there is no IO-520-T).
 
Dave Anderson said:
so do people lean out like 1/4” on takeoff because of the colder dense air ? I think density altitude was like -1200

This seems backwards I feel like you should only lean when it’s a high density altitude >5000 lets say

It’s a fuel injected Turbo it only had done it a fee times
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No ít should not be leaned at lower density altitudes. It needs to be enriched more.
 
I'm not exactly sure how the fuel metering works on that engine. But hp numbers are normally published at sea level at 15 degree celsius. So if you are below sea level or below a standard temp then more hp can be attained.
 
Also that engine with everything firewall forward is in the yellow on RPM and manifold pressure on takeoff Usually we pull back after establishing positive rate or climb at say 2-300 ft to get everything in the green
 
Dave Anderson said:
We are at full rich so does that means something g needs adjusted ?
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Yes. There is a mixture adjustment a knowledgable mechanic can and should set for proper fuel flow for WOT in accordance with your engine's factory Maintenance Manual. The A&P's who do it properly use calibrated gauges. Too many set the fuel system up by "ear" or "feel". I'd want a log book entry which states it was checked and set in accordance with the Continental M-O book.
 
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There is a complete setup procedure by Continental for adjusting the fuel on the TSIO-520 engines, it's rather extensive, and, sorry, I don't recall the number of that publication, I think it was/is an SB (service bulletin). The 340s I've flown, more or less the same engine, often had to be tweaked with change of seasons to get desired fuel flow for takeoff. Also, not surprised that with throttle firewalled for takeoff, you're slightly overboosting MP. Yeah, they can be set up just right, but may change over time. I've never flown a turbo 206 (or 210, or 340, etc., all similar engines) that you didn't have to watch your MP and stop short of firewalling the throttle.

Edit.: More or less what NordicDave is referring to, above.
 
My thought is a clogged/restricted injector. Conditions just right to show the issue? An engine monitor would easily show this, especially if you did try to lean it out a bit.

I have had this happen, engine runs great but when you tried to lean it out one cylinder EGT decreases while the rest increase. Essentially one cylinder is running lean of peak while the rest are rich of peak.

As I thought about it a bit more. The issue I saw above was that at full rich the one cylinder essentially was running at peak EGT, probably giving it the best chance of Detonation not sure that this would cause the reduction in power you are seeing. Or other WAG is that at full power take off the cylinder is loaded up enough from running full rich to keep it running ok until you get to about 300 feet then the mixture stabilizes at the to lean setting.

Brian
CFIIG/ASEL
 
Start with the Continental Service Bulletin and make sure the flows are properly set in the first place. In a turbo, which can always make SL manifold pressure regardless of local pressure altitude, the mixture should be forward.

A TSIO-520T (if that's what you are running) can go to 39.5 "Hg/2700 rpm, and fuel flows are in the low 30s in gps according to a very quick read of the set-up bulletin. Pressure would be above 33 psi as well.
 
brcase said:
My thought is a clogged/restricted injector. Conditions just right to show the issue? An engine monitor would easily show this, especially if you did try to lean it out a bit.

I have had this happen, engine runs great but when you tried to lean it out one cylinder EGT decreases while the rest increase. Essentially one cylinder is running lean of peak while the rest are rich of peak.

As I thought about it a bit more. The issue I saw above was that at full rich the one cylinder essentially was running at peak EGT, probably giving it the best chance of Detonation not sure that this would cause the reduction in power you are seeing. Or other WAG is that at full power take off the cylinder is loaded up enough from running full rich to keep it running ok until you get to about 300 feet then the mixture stabilizes at the to lean setting.

Brian
CFIIG/ASEL
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This flight roughness /bog was with fuel mixture rich before leaning.
 
Dave Anderson said:
We are thinking we may have had pump on low setting. I’m wondering if that caused enough fuel flow difference ? Even they we had high fuel PSI
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Note sure what you mean by pump on a low setting. Look at SID97-3G; the TSIO-520T is requires fuel pressure and flow in the low 30s. Unless you have a different engine - the letters at the end are the key for TSIO-520x family.
 
I would run the fuel system set up, spelled out in CAT (Cont Aero Tech, used to be TCM or "Continental")'s Standard Practice Maintenance Manual "M-0".
(previously known by the series of SIDs 97-XX). Look for 6-4.7.1. Fuel Injection System Specifications
Available free on CSOB website. (caution this link is a direct 186mb pdf download)
 
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Dave Anderson said:
TSIO-520M
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SID97-03G from 2015 indicates 33-37 psi unmetered fuel pressure and 29-31.7 gph full power flows and pressures for TSIO-520M. Likely similar values in current M0 manual, but your mechanic would have to check.
 
your mechanic will check for the latest version of M-0; this is what the CSOB version shows for TSIO-520
Appears to agree with Steam's post above

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