INTRODUCTION
This chapter describes the powerplant installed on Learjet 20 series airplanes. In addi-
tion to the powerplant, the chapter describes such engine-related systems as oil, fuel,
ignition, engine controls and instrumentation, engine synchronization, and the Dee
Howard thrust reversers.
GENERAL
T h e a i r p l a n e i s p ow e r e d b y t wo G e n e r a l
Electric, CJ610 single rotor, axial-flow turbo-
jet engines. The engines are installed in pylon-
m o u n t e d n a c e l l e s . T h e e n g i n e a s s e m b l y
consists of an eight-stage, axial-flow com-
pressor, driven by a two-stage turbine, an an-
nular combustion section, and a fixed-area
concentric exhaust cone. Each engine is at-
tached to the engine beam at three attachment
points. Eight thermocouples generate an av-
erage value of exhaust gas temperature, indi-
cated on the EGT gages in the cockpit. An
engine-driven starter-generator is installed on
each engine to provide engine starting and
furnish DC power to the airplane’s electrical
system. Compressor discharge air (bleed air),
through a mainframe port on each engine, is
utilized for cabin pressurization and cabin
heating, windshield defogging, wing anti-ice,
engine front frame anti-icing, and, on models
2 4 - 2 9 7 a n d s u b s e q u e n t a n d 2 5 - 1 3 5 ,
-181, and subsequent, for hydraulic reservoir
pressurization. On 24-350, -352, and subse-
quent and 25-227 and subsequent, bleed air is
also used for windshield/radome alcohol and
cabin temperature/pressurization control.
#1 DC
GEN
CHAPTER 7
POWERPLANT
7-1
FOR TRAINING PURPOSES ONLY
LEARJET 20 SERIES PILOT TRAINING MANUAL
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