Allison 250 Turbo-Shaft.

[Aesir]

I like that you call it an Allison and not RR

I read somewhere (500guy): "Rolls Royce claims allison 250 series engines have a 1:10,000,000 flight hour Design/Manufactured parts (properly installed) failure rate".

http://www.pprune.org/rotorheads/479...ure-rates.html