Pratt & Whitney Canada PT6,
From Wikipedia, the free encyclopedia, The PT6 is a turboprop aircraft engine manufactured by Pratt & Whitney Canada and is the most popular turboprop in history . It has an unusual design in that the air enters from the rear of the engine and the power section is at the front. However, it is the power section that requires the most maintenance and having it at the front makes it more accessible than burying it in an engine nacelle or the body of the aircraft.
Air enters the PT6A through a scoop at the rear of the engine, passes through a three-stage axial compressor, a single-stage radial compressor, then through the combustion chamber. The hot exhaust gases pass through a single-stage turbine which drives the engine compressor shaft, and then through a two-stage turbine which drives the propeller shaft, before exiting at the front of the engine. The PT6 is especially noted for its reliability and ease of maintenance. It is now sometimes chosen for projects simply because it is so well known and liked throughout the world.