Locking the fan is done on certain aircraft where a 3 engined ferry is allowed (i.e 146 due to inop engine) to get the aircraft to a maintenance base under strict conditions.
As for locking it on a ground runs, this would just cook the engine as it wouldnt get enough air. This for instance is why you never do a compressor wash or fresh water wash on a LF500 series engine below +4 degrees (I think) as the water could freeze the fan.