stabilization system is designed to maintain the
antenna beam at the selected tilt angle relative to the
earth's surface. The stabilization system uses the
aircraft vertical gyros as a reference and is comprised
of electronic amplifiers in the Receiver/Transmitter
interconnected with electro-mechanical components in
(7) Level Flight. Trim aircraft for straight and
level flight in smooth, clear air, over level terrain.
Select a 50-mile range and set STAB to OFF.
Rotate tilt control upward until all ground returns
disappear. Then rotate tilt downward until ground
returns just begin to appear. After several antenna
sweeps, check to see that ground returns are equally
displayed. If returns are only on one side of the radar
screen or uneven across the radar screen, this
indicates a misalignment of the radar antenna
mounting and should be corrected before proceeding.
Repeat this procedure until a balanced display is
stabilization off, select stabilization ON and tilt upward
once again to remove all returns. Rotate tilt downward
and check for even displays of ground returns. If this
test indicates improper display, possible errors in the
radar stabilization circuits or aircraft gyro exist.
It is typical of a processing aircraft gyro to
cause ground returns to first appear on
one side of the display, have them shift to
the opposite side of the display. This
precession may not be readily apparent
with respect to flight control instruments.
established in level flight, rotate the TILT control
upward in 1 increments until ground returns just
disappear, rotate an additional 2 upward.
Place the aircraft in a standard rate turn to the
right. Note the radar display. It should be free of
If returns display on the right side of radar
indicator, the radar system is understabilizing. Targets
on the left side of radar display indicate the system is
In prolonged turns, gyro precession may occur
which will be tracked by the stabilization system and
appear as undesirable ground targets on the indicator.
d. Maximum Permissible Exposure Level
(MPEL). Heating and radiation effects of weather
radar can be hazardous. Personnel should remain at
a distance greater than 5 feet from the radiating
antenna in order to be outside of the envelope in which
radiation exposure levels equal or exceed 10 mW/cm2.
The distance of the MPEL boundary is calculated for
the radar system on the basis of radiation diameter,
rated peak-power output, and duty cycle.
3C-35. TRANSPONDER APX-100.
Refer to Paragraph 3-5 for information on the
a. Description. The Stormscope System
consists of three components that detect, locate, and
map areas of vertical electrical discharge activity
contained within thunderstorms. The antenna mounts
externally to the aircraft and detects electrical
discharges associated with thunderstorms over a
125,000 square mile area around the aircraft. The
lightning and to determine range and azimuth for
display in the cockpit. The analysis is completed in
milliseconds. The location of a vertical electrical
discharge associated with a thunderstorm is plotted on
the CRT display on the instrument panel as an
individual discharge point (+).
b. Controls and Functions.
(1) Power/brightness Control. Rotate to turn
on the system and adjust the brightness of the display.
(2) Selector Buttons. The specific function of
each button is displayed adjacent to the button in each
c. Normal Operation.
(1) Self Test. Each time the system is turned
on it will automatically cycle through a series of self-
tests which ensure that all major functions are
approximately 15 seconds to complete, check antenna
reception, processor circuitry calibration, memory and
microprocessor function, and proper operation of the
options. After proper operation has been verified by
the self-test program, a confirmation message, ALL
TESTS ARE OK will display in reverse video. This
message will remain on the display for approximately
3 seconds and then will be replaced automatically with