CLEARANCE DELIVERY HEAD (CDH)
The clearance delivery head (CDH or CLR
DLY) is located on the right, front corner of
the center pedestal (Figure 16-18). The CDH
provides an alternative capability for tuning
the No.1 VHF COM transceiver and the No.1
VHF NAV radio. Also, the CDH can be used
to tune the VHF COM radio prior to applying
electrical power to the airplane.
The CDH control head is normally powered by
the left essential bus through the AUDIO 1 cir-
cuit breaker; however, it and other communi-
cation related equipment can also be powered
from the right forward hot bus, prior to ap-
plying electrical power to the aircraft.
With airplane batteries OFF, depressing the mo-
mentary action RADIO CTL HOT BUS switch
on the center pedestal applies power from the
right hot bus to the following equipment:
• Left and right audio control panels. (Some
earlier airplanes–left audio only.)
• CDH control panel.
• Comm section of the integrated commu-
nication unit #1. (ATC portion not pow-
ered.)
• Nav section of the integrated navigation
unit #1. (DME/ADF portion not powered.)
The RADIO CTL HOT BUS is only functional
when power is not applied to the left essen-
tial bus. When the airplane batteries are on, the
above equipment receives power from the es-
sential busses and the RADIO CTL HOT BUS
cannot be selected. If it was selected before
airplane batteries were turned on, the ON an-
nunciator on the RADIO CTL HOT BUS
switch will extinguish when airplane batter-
ies are turned on.
The display on the CDH is liquid crystal type
with white letters on a black background. The
pushbuttons, the display, and the control iden-
LEARJET 45 PILOT TRAINING MANUAL
16-26
FOR TRAINING PURPOSES ONLY
FlightSafety
international
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