The F50 has an electronic engine system, on take off the power levers are moved into a "gate" where they stay, climb power, MCT, go-around power etc are selected on the ERP (engine rating panel). During decent and landing the power levers are moved out of the detent (gate) and operated manually, in theory they cannot be moved past flight idle until a weight on wheels switch activates a solenoid, after which ground idle and reverse can be selected. There are no prop levers on the F50, the props are managed electronically by the PEC (prop electronic control) system. Also after landing the weight on wheels switch commands the ERP to select Go- around power in case of a missed approach, this is normally not a problem as the pilot would normally have selected ground idle by this point, if however the solenoid sticks as has happened before, the aircraft could accelerate!! If this happens the procedure is to feather the affected engine by closing the fuel lever, but this is alot to ask of a pilot already concentrating on a short field landing, by the time you realise what has happened it is too late.
I believe in the case of the luxair F50 this solenoid had stuck open allowing the power levers to be moved into ground idle while airborne with disasterous concequences, this is yet to be confirmed by the investigating authorities.
Hope this helps, Regards......