Learjet 20 Series Pilot Training Manual page 141

STATOR CASING
ROTOR BLADE
BALANCE
WASHER
OIL SLINGER
CARBON
SEAL
RUNNER
DISC SHAFT
NO. 1 BEARING
INNER RACE
FORWARD AIR
SEAL
stiffening ribs. The upper and lower halves are
bolted together along the horizontal centerline.
The casing is bolted to the front frame at the for-
ward end and to the mainframe at the aft end.
The compressor rotor assembly is made up of
an integrated front shaft-disc-spacer assembly,
a drive shaft, spacers, and eight stages of rotor
discs and blades.
Stall and surge protection is provided for the
compressor by the variable geometry system.
Variable inlet guide vanes operate in conjunc-
tion with bleed valves at the third, fourth, and
fifth compressor stages to provide a safe stall-
surge margin during acceleration, deceleration,
and steady-state operation.
7-4
LEARJET 20 SERIES PILOT TRAINING MANUAL
STATOR VANE
Figure 7-3. Compressor Section
FOR TRAINING PURPOSES ONLY
SPACER
AIR DUCT
ROTOR DISC
BLEED PORTS
Mainframe
The mainframe (Figure 7-4) section is the main
structural support of the engine. It consists of
a frame which houses the power takeoff hous-
ing and drive assembly and provides a mount
for the twelve fuel flow divider fuel nozzles,
the fuel manifolds, two eighth-stage air leak-
age check valves, and the gearbox assembly.
The eighth-stage stators and exit guide vanes
are mounted on twelve segments dovetailed
into a track cut into the front of the mainframe.
The No. 2 bearing is enclosed in a bearing sup-
port which bolts to the mainframe.
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CARBON SEAL RUNNER
NO. 2 BEARING INNER RACE
FORWARD HALF
COMPRESSOR DRIVE SHAFT
8TH-STAGE
AIR SEAL