Did it accelerate despite full pro-spin controls or was the stick allowed to come forward? Some power left on? Some aileron applied? Loaded outside C of G limits? I imagine you are talking about the Jordanian version which I think has an air conditioning pack in the rear. We used to spin the UK versions, normally to the left but not exclusively, normal and accelerated with no recovery problems beyond a delay in the accelerated case. Genghis is right, there is no general problem with the Firefly, you would have to be more specific.