Low Load on Take-off

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Ed McDonald
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Low Load on Take-off

Post by Ed McDonald »

My new DA62 presented the following issue. When applying full power on the ground the left engine does not produce maximum load (94% vs 98%). When the throttle was reduced by about 1/2 a knob the load increased to near that of the right engine. This test was done with ECU A and B with the same results. See the photos attached.
The left prop governor was replaced (kudos to Diamond Canada for getting the replacement delivered the next day) with no change. The power split in the air improved but no significant change on the ground.
Any ideas what the problem may be? My maintainer, Diamond Service Centre, thought it would be the governor but doesn’t look like the issue.
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Boatguy
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Re: Low Load on Take-off

Post by Boatguy »

I observed an anomaly like this on the DA62 on which I was doing training a couple of weeks ago. Pulling back the throttle from 92%, it would briefly jump up to 100%, then back down. I suspect the "Hall effect" throttle rather than the engine. Perhaps contamination of a faulty sensor. I believe the ECU data will show power called for which can be compared to power produced.

That said, you just replaced the governor on that side and the governor has some settings that might not be correct. And the governor on the training plane failed the third day of training, though I'm not sure if it was the same engine on which I saw the power anomaly.
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robottwo
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Low Load on Take-off

Post by robottwo »

I’ve seen the same thing on the left engine on my DA62. I had a problem with the prop governor and waste gate controller on that engine a while ago, and I suspect it hasn’t been fully tuned. I’m planning to have it looked at in my next annual, but it’s only been a few %.

Having said that, I used to see the same thing on my cheap joystick when playing games on my PC. Given that it’s a digital throttle, it could just be a glitchy sensor on the throttle knob itself.


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Re: Low Load on Take-off

Post by CFIDave »

My DA62 has always suffered from the same issue: I only get 97-98% power with the levers full forward, but if I pull them back slightly I can get 100%. It's because the hall effect sensors that read the throttle lever positions aren't adjusted properly.

Years ago when my DA62 was still under warranty, I asked a Diamond Service Center to fix this. They adjusted the position sensors using the Austro Engine Wizard software to show 100% load when levers were full forward, but this didn't change what shows up on the G1000 when the engines are running.
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thommy152
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Re: Low Load on Take-off

Post by thommy152 »

Does the load % show the actual power output percentage of the engine or simply the requested load % by virtue of the throttle position?
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Re: Low Load on Take-off

Post by Karl »

thommy152 wrote: Thu May 19, 2022 10:38 pm Does the load % show the actual power output percentage of the engine or simply the requested load % by virtue of the throttle position?
On the Continental Diesel engines with the engine shut down it will indicate throttle position, with the engine running it is a calculation of the load based upon a number of things, MP, RPM etc.

I know this is an Austro but they are pretty much a copy of the CD engines so there is a high chance it is the same.
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Re: Low Load on Take-off

Post by thommy152 »

Thank you, Karl. I’ve been curious about this for a while, but couldn’t find anything in the engine manuals that gave me an answer.
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Re: Low Load on Take-off

Post by Davestation »

Curious that their first suspect was the governor when it seems to be making rated RPM? If it wasn't making rated RPM then the max pitch stop could be adjusted. The first thing that caught my eye is that the fuel flow on the left is significantly lower than the right. This could be due to improper rigging of the power lever sensors, or something else. Did they do a live data download? That should easily confirm it.
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