Pilot's Operating Handbook
Section 7
Description
Edition 0 - March 05, 2019
Rev. 0
Page 7.6.1
7.6
- Powerplant
Turboprop engine operation
- see figure 7.6.1
The PRATT & WHITNEY CANADA turboprop engine (PT6A-66D model) is a free
turbine engine rated at 850 SHP and developing a thermodynamic power
of 1825 ESHP.
Intake air enters engine through an annular casing and is then ducted toward
compressor. The latter consists of four axial stages and one single centrifugal stage
assembly to form a whole assembly. Compressed air and fuel are mixed and sprayed
into combustion chamber by fuel nozzles. The mixture is first ignited by two spark
igniter plugs, then combustion continues as a result of air-fuel mixture flow. Gases
resulting from combustion expand through a series of turbines. The first one (gas
generator turbine) drives compressor assembly and accessories, the two other ones
(power turbines), independant from the first one, drive propeller shaft through a
reduction gear box. Hot gases are evacuated through two exhaust stubs located
laterally on both sides forward of engine cowling.
All engine driven accessories, except power turbine tachometer, propeller governor
and overspeed governor are installed on accessory gearbox located rearward of
engine.
PIM - DO NOT USE FOR FLIGHT OPERATIONS
