ground, turn the bleed air valve
switches to ENVIRO OFF position.
AC/DC power Check for:
AC frequency 394 to 406 Hz.
AC voltage 104 to 124 VAC.
DC load Check.
DC voltage 28.0 to 28.5 VDC.
Do not operate radar in congested
areas. Injury could result to
personnel in close proximity to
Do not operate the weather radar in
an area where the nearest effective
surface is 50 feet or less from the
antenna reflector. Scanning such
surfaces within 50 feet of the
Avionics master switch ON.
Mission panel Set and checked as required.
Electric elevator trim and autopilot/flight director
operation Check as follows:
Pilot's and copilot's 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 manual trim.
DISC TRIM switch Press to second detent
and verify that electric trim disconnects and
ELEV TRIM annunciator light (in pedestal)
Flight director (FDI) and Radio Magnetic
Since the pressure of airflow that
normally opposes movement of
control surfaces is absent during
preflight check, it is possible to get
deflection if an autopilot command
is allowed to remain active for any
appreciable length of time. Move
turn knob and pitch thumbwheel
only enough to check operation,
then return them to the center
Autopilot mode selector panel Select HDG
Horizontal Situation Indicator (HSI) Set
heading marker under lubber line.
Autopilot Engage. Check that controls are
stiff and that AP ENG, HDG, and AIL HI
TORQUE annunciator lights illuminate.
AIL HI TORQUE test switch Engage.
HSI heading marker Move 10° left and right
and verify that flight director and control
wheels respond in the appropriate direction.
(control wheels) Press to first detent and
verify that autopilot disengages (AP DISC
annunciator illuminates) and that flight
controls are free.
extension) Command 5° trim UP and verify
that manual trim wheel moves nose up and
AP trim light indicates UP trim.
Command nose down and verify that
autopilot disengages and AP TRIM FAIL
and MASTER WARNING annunciator lights