There is no official information yet. However, two things to note:
1. This was a flight with two very experienced instructors, presumably doing some continuation training exercises.
2. The crash site photos imply an almost vertical impact with little or no pitch angle. I remember seeing confirmation of this somewhere else. The second photo I posted shows an impact scar which might indicate rotation, but it might also have been caused by the wreckage sliding downslope.
I've not been able to find any information on stall-spin Tecnam twin accidents.
Second hand information as I've not flown it but friends who do operate it say the stall characteristics are closer to a Tomahawk than a Seneca however that is just a lead in from the last comment above about stall/spin. I've got no idea as to the cause here, haven't looked into it at all.
It's been a while since I looked this up but twin engine aircraft have no certification requirements as far as spins...as you're not supposed to spin them. I don't know of any GA twin which is authorized to spin. But an accident with two experienced instructor pilots is usually training related which would lead you to believe a SE demo gone wrong.
14. APPROVED MANEUVERS The aircraft is certified in normal category in accordance with EASA CS-23 regulation. Non aerobatic operations include:
Any manoeuvre pertaining to “normal” flight
Stalls (except whip stalls)
Turns in which the angle of bank is not more than 60°
And then, with a big red warning triangle next to it:
Acrobatic manoeuvres, including spins and turns with angle of bank of more than 60°, are not approved for such a category. In addition, stall with one engine inoperative is forbidden.
...and from Section 3, with another red triangle:
The spin recovery has not been demonstrated during certification process being not required for this aircraft category. Should an unintentional spin occur, the classic recovery ma- noeuvre is deemed as being the best action to undertake.
Thank you for that information, which was as I suspected.
During some searching, I stumbled on this interesting video of spin-testing a Beech Duchess:
As pointed out in the video, even after successful spin-testing during certification test-flying, the Duchess was certified in the Normal Category and placarded "Normal Category Aircraft: No acrobatic maneuvers, including spins, approved."
Normal category singles may be spin approved, but are not required to be. They will, however, for certification, have demonstrated recovery from a one turn spin in no more than one additional turn. Nothing says that this recovery has to be easy, just possible.
Utility category aircraft, if to be spin approved, are required to demonstrate recovery from more demanding spin conditions.
The forgoing shows the difference on the spinning categories approved for the 172 - normal vs utility.
Multi engined aircraft are not required to demonstrate spin compliance at all for certification, unless they are requesting spinning approval as a utility aircraft. I'm not aware of any examples of this. They are required to demonstrate single engined stalls, but if you're spinning a multi engined aircraft you are probably a test pilot for that flight.
That accident report is pretty interesting reading. I have not flown the Tecnam, but other types I have flown, including the Partenavia Observer, demonstrated good tolerance to wing drop and spin entry, when flown within their certified parameters. The flying I did on these types included single engined and 30 degree banked stalls. Though I was guarding myself for an upset, I was always rewarded with a benign aircraft.