7-19
FOR TRAINING PURPOSES ONLY
LEARJET 20 SERIES PILOT TRAINING MANUAL
FlightSafety
international
CONTROL AND INDICATION
The thrust reverser control switches and an-
nunciator lights are located in a subpanel
mounted either above the glareshield light
panel or in the center instrument panel (Figure
7-16). Switches are provided to arm the sys-
tems for normal operation, emergency stow-
ing, and for the test functions. Annunciation
lights are provided to indicate left and right
system armed, unsafe, and deployed. With the
control switches in NORMAL and ARMED,
the deployment or stowing of the thrust re-
versers and engine rpm in reverse is controlled
by piggyback subthrottles (see Figure 7-13)
mounted on the engine thrust levers. The sub-
throttles can be raised only with the engine
thrust levers in the IDLE position.
Raising the subthrottles to the IDLE detent
position deploys the reversers with no in-
crease in engine rpm. A mechanical lockout
prevents engine acceleration in reverse until
the appropriate doors are deployed. A ground
adjustable stop in the thrust levers limits en-
gine rpm in reverse to a maximum of 85%. A
system of mechanical and electrical inter-
locks is provided to prevent unwanted or in-
advertent deployment. With the engine thrust
levers in forward thrust above idle, the T/R
system cannot be armed. Electrical inter-
locks are provided through landing gear squat
switches to prevent in-flight deployment.
AUTOMATIC STOW
An automatic stow system is also incorpo-
rated into the system. In flight, a stow com-
mand is automatically introduced whenever the
T/R is in any position except fully stowed.
EMERGENCY STOW
An emergency stow switch is mounted on the
control switch panel (Figure 7-16). Actuation
of this switch bypasses all interlocks and all
other signals with a direct stow command if
the ARM switches are off. Proper functioning
of the normal deploy/stow and emergency
stow systems is accomplished during system
checkout. If a malfunction is indicated, flight
with the system disabled and safety pins in-
stalled is permitted.
NOTE
With the ARM switches on, the emer-
gency stow function is inoperative.
With switches to EMERG STOW, the
arm function of the system is inoper-
a t ive . Fo r l i m i t a t i o n s , p r e f l i g h t
checks, normal and emergency proce-
dures, consult the AFM.
Figure 7-16. Thrust Reverser Control, Test, and Indicating Panel (Typical)