DA40 NG, available power check

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Pipeorgan
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DA40 NG, available power check

Post by Pipeorgan »

Where should the available power check be performed and for how long?

The Diamond checklist edition 17.3 states that it should be performed as the last item on the line up procedure which implies that it is performed on the runway. However the AFM states that it should be performed as one of the last items on the before takeoff check list, which implies that it should be performed in the run up area!

In both cases it states that full power, as per the OAT/Altitude table, should be applied for 10 seconds with the brakes on. Do pilots always do this as I have been told by some pilots that this is excessive and not necessary?!
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Re: DA40 NG, available power check

Post by jast »

I do it on the runway: go to a full stop at the takeoff point and hold the breaks, set full power and when it reaches the expected power output + 1 second I let the brakes go and execute the takeoff. It is important to let the power settle as the moving air can already influence the achievable power according to my MEP training in the DA62. For sure the 10s recommendation is very conservative. Maybe on a 8000ft rather short runway I would do that as safety precaution.

Hope that helps.

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Jan
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Re: DA40 NG, available power check

Post by Pipeorgan »

Thanks Jan for the advice. My runway, for the winter, is a very short 498 m which I guess I should have mentioned in my original post. Are you then advising me to hold on the brakes, at the take off point, with full power for the full 10 seconds?
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Re: DA40 NG, available power check

Post by jast »

At least hold with full power until you see the expected power level (there is a table in the checklist depending on pressure altitude) and add a few moments to be comfortable that the power is stable.
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Re: DA40 NG, available power check

Post by Pipeorgan »

Thanks for the response. Yes that’s what I am doing at the moment as I can’t really hold on full power for 10 seconds on the runway as ATS and other pilots would not be too happy as I am supposed to be ready for departure😊
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Re: DA40 NG, available power check

Post by CFIDave »

I don't perform a separate "available power check" on Austro-engined aircraft, since I don't think it's necessary.

If making a short-field takeoff where applying full power before releasing the brakes, you're already performing the power check before brake release.

And if making a normal takeoff with plenty of runway -- applying full power while rolling down the runway -- you can check for full power while the aircraft is accelerating. If you're not happy with the power indication, then immediately close the throttle(s) and abort early during the takeoff roll. I've had to do this more than once after the "con-rod fail-safe bridge AD" was performed on my Austro engines, and one engine's turbo boost controller rod was mis-adjusted by the maintenance shop; it does get exciting on a twin with asymmetrical thrust, but easily handled. :)
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Pipeorgan
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Re: DA40 NG, available power check

Post by Pipeorgan »

OK many thanks for the clarification. Seems as if no-one thinks that applying full power for 10 seconds with the brakes on, as specified in the DA40 NG AFM, is necessary for an available power check. Maybe I should check with Diamond as I am always being reminded that tests and checks should always be performed according to the AFM!
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Re: DA40 NG, available power check

Post by AaronF »

During the factory training in Neustadt, our instructor advised against available power checks with stationary airplane, especially when performed on places other than the runway - and to definitely avoid it on grass airfields.
He said the check could be easily performed during the take-off run: Smoothly apply full power + verify load % and other engine parameters within normal range.
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Re: DA40 NG, available power check

Post by Colin »

+1 for the power check on the runway. I was taught (by a Diamond Flight Academy, back when they were certifying and naming things), hold brakes until 50% was reached, confirming green-green-lotsa-green, then release brakes. Watch engine parameters, especially percentage power, as we accelerated to rotation speed.
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