Apparently back in the olden days, there was a procedure on the 3 to deliberately seize the engine. I’m not sure if me old mate is having a lend of me on this, but he swears it is true.
If the controllability of the aircraft was compromised by an uncontrollable overspeeding prop (for example, would not feather due Feather pump u/s) the idea was to close the Emergency Fire Shut Off Valve. This would shut off the engine oil, engine seize, the prop shaft would shear at the prop gearbox outlet and prop separate…overspeeding prop fixed!
That was the theory. In practice, it could get a bit messy. For a start, if the prop did not separate, the drag of the frozen prop was greater than a windmilling prop. But assuming it did separate, apart from the risk of substantial damage to the fuselage, if the gearbox inlet sheared instead of the outlet you had a rotating gearbox without oil cooling. The overheating would ignite the magnesium gearbox casing. Of course the prop and gearbox assembly would soon separate so then all you had to deal with was an uncontrollable engine fire.
Dose any one know if there is a skerrick of truth in this or is me old mate taking the piss?