Yes I know that this is so old.I am an eye witness of an accident in witch my brother and a student lost their life's. That was 20 years ago,the investigation did blame the instructor but that is not the point.I will have it in front of may eye's for the rest of my life and it did puzzle me what rely happen there it is not going to bring life back but my save someone other people.

So Christian Ortner writes :

"Probably when trying the halv snap roll, the
wooden support of rudder segment were the pins of the rudder grip in is broken,
so the rudder action was not ok"

After reading this now everything makes sens. They had no rudder.

I did find a document witch stets that during development and trials of szd 50 they had a massive problem with recovering form spins so they did redesign the elevator to fix this