Originally Posted by
A Squared
It's possible. There are systems in the prop intended to prevent a prop going into flat pitch in flight, but like anything, they're not infallible. I know of at least one instance where a prop has gone below the low-pitch stop in flight.
An overspeed with a failure to pitch lock and a runaway propeller can cause a severe yawing motion and application of power makes it worse, as does any increase in airspeed.