SECTION 7
DESCRIPTION
TBM
700
PILOT’S OPERATING HANDBOOK
Page 7.6.1
Edition 1 -- November 30, 2010
Rev. 0
7.6 -- POWER PLANT
TURBOPROP ENGINE OPERATION
(Figure 7.6.1)
The PRATT & WHITNEY CANADA turboprop engine (PT6A--64 type) is a
free turbine engine developing thermodynamic power of 1580 SHP, derated
to 700 SHP.
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 and
propeller governor, are installed on accessory gearbox located rearward of
engine.
PRATT & WHITNEY CANADA PT6A--64 turboprop engines do not require
any specific running--in procedure. They can be safety used in all normal
ranges allowed by the manufacturer at the time of delivery of the airplane or a
new engine or an engine having undergone an overhaul or a reconditioning.
