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Pipistrel Electro accident in Norway, and electric propulsion reliability

There was a loss of power accident with a Norwegian Pipistrel Electro today.

Translated from an interview with the pilot in Norwegian media:

- We were heading towards the airport when there was an indication that something was wrong with the engine power. Then the engine power weakened and disappeared completely. Then I had to send a mayday and try to find a place to land, he said, adding:

- There was a lot of forest there, so I headed for a lake on which we landed.

The pilot was the managing director of Avinor, the Norwegian ATS and state airport company. No injuries to the pilot and passenger.

Last Edited by Airborne_Again at 16 Aug 13:11
ESKC (Uppsala/Sundbro), Sweden

It was two days ago actually. Glad he made it OK. Judging by the terrain there, he did a very good job. According to him he had 80% battery charge. The engine just quit for some reason.

The elephant is the circulation
ENVA ENOP ENMO, Norway

A great pity. I saw that aeroplane at ENKJ Kjeller about a year ago and had to pass up an invitation to ride in it due to a pressing schedule. The big fear with AC motors has to be inexplicable driver transistor failure and it will be interesting to discover what happened here. The pic makes it look as if he’s ditched long right up to the shoreline, quite an achievement if that’s right.

EGBW / KPRC, United Kingdom

Aveling wrote:

The big fear with AC motors has to be inexplicable driver transistor failure and it will be interesting to discover what happened here

Do they really use bog-standard AC motor electronics for aviation? I would certainly hope that they either have a separate set of circuits to take over, or design one that can keep going if a single component fails, and self-diagnose to announce such a defect.

Last Edited by Cobalt at 16 Aug 14:31
Biggin Hill

The big fear with AC motors has to be inexplicable driver transistor failure and it will be interesting to discover what happened here.

Indeed – damn hard to make power electronics reliable enough for this job. One can over-engineer everything massively, which helps, but it is obvious from the various development grant applications exhibits that a lot of heat is being generated / a lot of cooling is needed, and thermal cycling is the biggest killer of power electronics.

And it is difficult to have a duplicate inverter (brushless motor drives tend to be called “inverters”) and have a means of switching over to it. It will increase the cost a lot, and the heavy currents would probably need a large mechanical switchover arrangement. I doubt anybody has an appetite for going down that route. It’s different with say a train, which just stops…

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

It’s different with say a train, which just stops

Or not. Typical electric locomotive has 4 independent traction motors with independent controllers (‘sepex’ – separately excited – mainly for wheelslip control rather than redundancy). Weight is also a much smaller issue with a locomotive so you can just make stuff beefier.

Last Edited by alioth at 16 Aug 14:41
Andreas IOM

alioth wrote:

4 independent traction motors

Indeed. And the way forward with aviation may be multiple motors too, but no doubt the efficiency suffers with smaller props and more gubbins generating drag. I’m still uncomfortable with the propensity of power electronics toward ‘inexplicable’ failures, though the reliability being achieved in cars probably far exceeds IC engine standards The trouble is that an aeroplane is full power all the time, something not seen in other applications where over engineering is King.

EGBW / KPRC, United Kingdom

Great job by the pilot, but I would also give some credit to the airplane.

If you take a look at the video in the link above, the plane has barely any damage. They just take off the wings and carry it out of there. Also no AVGAS in the lake, good for the fishes ;)

ESME, ESMS

“Also no AVGAS in the lake, good for the fishes”
Can the batteries leak anything? If so then possibly longer lasting and more harmful than avgas.

Maoraigh
EGPE, United Kingdom

Last time I put a lithium battery in the water it didn’t leak anything. Although I set it on fire first.

ESME, ESMS
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