I have had one real failure, and 2 precautionary shutdowns in my 8k hours of PT-6. 1. bad bearing overtemp, chewed up hot section 2.blown prop seal/smoke in aircraft precautionary ie: still made power, but for how long, 3. low oil pressure/leak shutdown at 60 psi as per mfr's instructions.
I Love them, but you would have to pay me an awful lot to fly a single again.