DA42 TDI Cold weather operations

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MAGDOM
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DA42 TDI Cold weather operations

Post by MAGDOM »

Newbie to the forum, new to the DA42 TDI.

Looking to see other owners experience with operating the Continental CD-135 engine in the DA42 TDI in a cold weather climate. As we train with our TDI in cold weather (by cold weather I mean 0 degrees C or colder), when practicing simulated engine failures, we have found our TDI exhausting heavy white smoke after 2-3 minutes of engine operation at idle power. This is followed by a rough running engine and the inability to resume full engine power. Power is regained after some time while operating the engine at 55-60 % power, and cycling the power control back and forth from idle to full power setting. This has been experienced with both engines (separately of course) somewhat eliminating the chances that the issue is isolated to one engine over the other. No indications of any faults appear on the G1000. Aircraft is being flown with full fuel

Any thoughts on this? Could this really be a characteristic of the Continental Diesel in cold weather operations?
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Karl
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Re: DA42 TDI Cold weather operations

Post by Karl »

We would need a lot more information to be able to give any diagnosis of the problem. White smoke can indicate unburnt fuel which could be related to the cold. It does sound like it could be low fuel temperature.

What fuel are you using?

I would really need to see fuel temperatures, pressures, coolant and manifold data to offer any advice.

Best thing would be to contact Continental Diesel with a data download so they can analyse it.

Please let me know what response you get from them.
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ememic99
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Re: DA42 TDI Cold weather operations

Post by ememic99 »

I can't say I operate DA42 TDI in particularly cold climate (winter temperatures on the ground go to -5) but I regularly fly it in temperature range down to -30 degrees Celsius (at FL180) without any problem. I'm now on the second set of engines, previously I had Thielert 2.0, now I have CD-155. I remember that sometimes Thielerts used to throw white smoke on startup in winter but no rough running or instable RPM.
MAGDOM
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Re: DA42 TDI Cold weather operations

Post by MAGDOM »

We are operating these engine with Jet A-1 fuel all of the time. Temperatures and pressure were slightly lower than the fully operating engine, but still in the green arc indicating normal acceptable parameters.
An ECU download was sent to Continental Diesel right away after the first time this was experienced. Continental's response was to check the gearbox oil level, the gearbox filter and gearbox preset pressure. They even suggest increasing the gearbox pressure 2-3 bar for cold weather operation. One engine was adjusted at that time. They also suggested to inspect the induction and wastegate for freedom from jamming. We found no defects with either engine.

A second download was sent to Continental Diesel since it reoccurred again with the colder days we have been experiencing. Awaiting a response on that.
We do not see this same issue on the warmer days.

Thanks for your input.
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Re: DA42 TDI Cold weather operations

Post by Karl »

Loaded question, is anyone adding anything to the fuel? Prist for instance?

Not sure what CD are thinking with the gearbox oil etc, that would affect prop pitch and RPM.

To me white smoke sounds like unburnt fuel, especially combined with rough running. Sounds like at least one cylinder isn't firing.
I would be looking at MAP temperature/pressure, fuel temperature, rail pressure, coolant temperature etc. Things to do with combustion.

Can your engineers reproduce it on the ground and do a real time download?

Perhaps try doing single engine ops with the dead engine at slightly higher power 10-14%. I believe some think that better represents a feathered prop. I understand Diamond do the training with it closer to 20% though most think that is too high. Might be worth a try to see if it eliminates the problem.
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Re: DA42 TDI Cold weather operations

Post by Davestation »

Was this resolved? Definitely sounds like flame out - combustion chambers getting too cold from the combo of low ambient temp and low power setting.
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