PC-6 Engine Performance

Horsepower

The aircraft is powered by a Pratt & Whitney PT6-27 engine which produces 550hp at 101.5%Ng (38,100rpm) [TCDSr13].  The same engine installed on a deHavilland Twin Otter -300 produces 620hp at 101.5%Ng (38,100rpm) [1].  It seems then that Pilatus derated the PT6-27 engine by reducing the Np speed by ~100rpm and possibly reducing the pitch of the propeller although this can't be verified by comparing the two TCDS documents.

References

[1] deHavilland Twin Otter TCDS A9EArev15 held by Viking Air Limited
http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/408846401A43B20386257A44005C3957?OpenDocument