an uncontained PRT failure started a fire...
Same thing brought down a Northwest DC7 just north of Manila, as I recall.
When the PRT failed, it would initially torch out the exhaust stack, big time, and would be noticed by an approximate 20 BMEP decrease on the affected engine.
Shutdown, right now.
The CurtisWright turbocompound engine was a paragon of efficiency, but somewhat unreliable in service.