Stab trim can run away and there are two cut out switches next to the power levers. Haven't heard of it failing. QRH doesn't mention any limits if one yaw damper fails, but MEL says the acft needs at least one of the yaw dampers. The acft is great to fly, good luck with the type rating, I know a couple of Biochemists that fly commercially. With the spiraling cost of drugs (medicinal type) I would have thought it would be well paid.