When I had my interview for a trainee position, I was asked very little technical questions. If you could call them technical questions at all! I was asked basic things like why do we have an APU. Name the different sources of electrical and hydraulic power. I was then asked about VSV's and VBV's. So my advice would be to obviously just have a basic understanding of aircraft systems.
Most of the interview was HR related. What would you do in this situation? Describe a time when you had to do this? Etc. That was the main bulk of the interview. Obviously you need to understand a bit of the companies history. I think that is a real HR pleaser, when they see you have taken a keen interest in not only the role that you are applying for but also the history behind the company. You could maybe also try to find out what the company plans to do for the future. They obviously don't want you to obtain your licences through the company and then leave! I think in these current times, loyalty goes a long way.
Just a few thoughts. Good luck!
