Recent purchase of this aircraft, not too impressed, does not behave as well as some others or even FSX standard Aircraft.

However, this could be teething problems

But, only with this Aircraft, when i click "End Flight" it closes FSX entirely!

Every time and only this Aircraft.

What is the fix please guys?

 

Cheers

Baz

P.S.

One more small thing, I am unable to change the Tail Number on the physical Aircraft!

 

It is not uncommon with FSX aircraft because the memory management inside FS is not the best. I have seen it happen with almost any aircraft, not the Katana though. I have no work-around for that at the moment. 

It only crashes on this Aircraft and no other! FSX standard or any of the multiple add on 3rd party aircraft

On your system. On one of my systems all of the PMDG aircraft do it.  It's an issue we are unable to correct, sorry.