Bruce is correct. I did not mean to mislead, just attempting to help.

The failsafe simply lets you set servo positions in the event of loss signal.
His explanation is more accurate and the fact that is can still crash is very true.

PCM modulation does indeed require the PCM capable reciever. Many Futaba PCM receivers avialble.
The recivers will tell you in their specs if they are PCM or PPM.
A PCM Receiver is just PCM, cannot be set for either like the TX. Must change the Paramater setting on the TX to match the reciever.
Futaba instruction manuals explain all.