Pratt & Whitney Canada PT6A-27

The PT6, manufactured by Pratt & Whitney Canada, is the most popular turboprop aircraft engine in history.
It is produced in a wide variety of models, covering the power range between 580 and 920 shp in the original series, and up to 1,940 shp in the "large" line.
Development of the PT6 family started in the late 1950s, apparently as a modern replacement for the Pratt & Whitney Wasp radial engines they were producing at that time. It first flew on 30 May 1961, mounted on a Beech 18 aircraft at de Havilland Canada's Downsview, Ontario facility. Full-scale production started in 1963, entering service the next year. By its 40th anniversary in 2001 over 36,000 PT6As had been delivered, not including the other versions.

The engine consists of two sections that can be easily separated for maintenance. In the gas-generator section air enters through a grill into the low-pressure three-stage axial compressor, then into a single-stage centrifugal compressor, through the annular reverse-flow combustion chamber, and finally through a single-stage turbine that powers the compressors at about 45,000 rpm.
Some power is also taken off of the compressor end of the shaft to power an accessories section, which also loads the engine when idle to keep it from racing out of control.