Engine failure on Astro DA42-VI

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Karl
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Re: Engine failure on Astro DA42-VI

Post by Karl »


That description makes it sound more confusing to me. The whole point of autofeathering is if you lose oil pressure, ie the engine shut down. I think the POH is describing a loss of oil pressure but making it sound backwards. Oil is flowing back from the hub because of the loss of pressure. The counterweights are what automatically drive it into feather, you just need to be above 1300rpm for the high pitch stops to be disengaged.

And when it says accumulator pressure is “restored” it should say “stored” as the accumulator is holding system pressure all the time while the engine is running. The valve needs to close to lock in that pressure so that when you go to restart the engine the valve will open and dump the accumulator pressure to unfeather the prop. Oil pressure is what keeps it out of feather, so loss of oil pressure puts it into feather.

I suppose they’re saying you have to turn the master switch off to feather it (on purpose) because that’s the expected scenario. I don’t think that means if you don’t turn the master switch off feathering will be prevented in case of engine failure. Although unless you starve it if fuel the only likely scenario where the engine quits involves an electrical failure so at that point the switch is effectively off anyway.
As an engineer, this is exactly my understanding.

Recently we had an issue where the hose to the accumulator chafed and started to leak.

The pilot reported that the engine slowly lost RPM despite the throttle being at full power.
This was of course due to the prop becoming more and more coarse due to the reduction of oil available to keep it in fine pitch, it would have eventually moved into the fully feathered position had the pilot not elected to shut it down/feather it manually.
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krellis
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Re: Engine failure on Astro DA42-VI

Post by krellis »

Curious as to what happens with the current Austro piston problem - does the engine seize up and if so, how do you then feather the prop?
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Mdm0515
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Re: Engine failure on Astro DA42-VI

Post by Mdm0515 »

Has anyone seen any additional reporting on this incident re cause?
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