Originally Posted by
Australopithecus
Nope. They cannot make an engine containment ring strong enough for turbine blades, so imagine the energy in a much heavier object released from the hub. A friend was once torpedoed by a runaway towbar as they we’re taxiing onto the gate in a Convair 580. The engine was already running down when the towbar hit the prop (at 700 rpm). The blade released and ended up 200m away planted vertically in the ramp.
Actually, turbine
blades are required to be contained (as are compressor blades - including the fan) as a cert requirement. They can come out the back (or front) as low energy debris, but not out the side. Turbine (and compressor/fan)
discs are another story - the energy is so high that containment is simply not practical (we're talking inches of armor plate).
I'm not sure how practical it would be to shield passengers from propeller intrusion - the energy of a released prop is going to be very high, so it would take a considerable amount of Kevlar/carbon fiber/whatever to prevent intrusion, and due to the aerodynamic properties of a prop blade, the trajectory is rather unpredictable so the potential impact area of the fuselage would be rather large.
I did some work on another proposed installation of the engine used on the Saab many years ago, and as I recall the prop was certified as primary structure - i.e. it should never fail - because if they lost a prop at power the resultant imbalance could fail the wing structure.
Then again, I don't think the structural cert requirement for the props included impacting a rock wall...