5 seconds, then ON.
When voltage drops below approximately
20 volts, the red anticollision light may
8-28. BEFORE TAXIING.
1. BLEED AIR VALVES As required.
2. BRAKE DEICE As required. To activate
the brake deice system, proceed as follows.
a. BLEED AIR VALVES OPEN both.
b. CONDITION levers HIGH IDLE.
c. BRAKE DEICE switch DEICE on.
Check BRAKE DEICE light illuminated.
CONDITION lever may be returned to LOW
Brake deice control valves may become
inoperative if valves are not cycled
periodically. One cycle of the valves is
required daily, regardless of weather
3. CABIN TEMP MODE and temperature
switches Set as desired.
For maximum cooling on the ground, turn
the BLEED AIR VALVE switches to ENVIRO
4. AC/DC power Check as follows:
a. AC frequency 394 - 406 Hz.
b. AC voltage 104 -124 Vac.
c. DC load 85% maximum per generator.
d. DC voltage 28 - 28.5 Vdc.
5. AVIONICS MASTER POWER switch ON.
Do not operate radar in congested areas.
Do not operate the weather radar system in
a confined space where the nearest metal
wall is 50 feet or less from the antenna
reflector. Scanning such surfaces within
50 feet of the antenna reflector may
damage receiver crystals.
6. Avionics controls As required.
The radar system should be tested before
each flight on which the system is to be
used. If no significant weather is in the
immediate area of the aircraft, the system
should be left in the STBY position.
7. Electric elevator trim, autopilot/flight director
operation C D1 When PC determines
that an autopilot check is required, check as
a. Pilot and copilot PITCH TRIM switches
Press to NOSE UP and NOSE DN
positions, singularly and in pairs. Check
that trim wheel moves in proper direction
and operates only when trim switches
are pressed in pairs. Any deviation
requires that electric elevator trim be
turned off and flight conducted using only
b. DISC TRIM switch Press to second
detent and verify that electric trim
disconnects and that ELEC TRIM light
c. Flight Director (FD) and Radio Magnetic
Indicator (RMI) warning flags masked
Since the pressure of airflow that normally
opposes movement of control surfaces is
absent during preflight check, it is possible
to get a hard over control surface
deflection if an autopilot command is
appreciable length of time. Move turn knob
and pitch thumbwheel only enough to
check operation, then return them to the
d. Select HDG mode Check.