NAVAIR 01-1A-509-3
01 March 2005
TM 1-1500-344-23-3
TO 1-1-689-3
Chapter 2), soaked with the Water Displacing,
a. Moisture and fluid intrusion (rain, condensation
Corrosion Preventive Compound, MIL-C-81309 Type II,
fuel, or hydraulic fluid).
so the fluid can penetrate around the individual strands.
b. C o r r o s i v e elements in the surrounding
g. To prevent moisture from entering the insulator,
atmosphere.
fill the space around the wire where it enters the
insulator with Room Temperature Vulcanizing,
c. M a l f u n c t i o n i n g
or
inadequate
shop
Adhesive Sealant, RTV 3140, Clear, MIL-A-46146
environmental control systems.
(Volume IV or V, Chapter 2). Seal both ends of the
insulator in this manner.
d. Malfunctioning or inadequate built-in filter
systems.
6-3.1.12. Antenna Bonding/Grounding Connection
Electrical Resistance Test. The electrical resistance
NOTE
test is performed after an antenna base is mounted or
ground installation is assembled. The test shall take
In this section, use of the term "avionic test
place prior to applying sealant, if applicable. Proper
equipment" shall refer to all aircraft electrical
torquing of connections , good resistance readings,
and electronic system test equipment. This
and complete sealing are all essential to ensure a
includes support equipment, oscilloscopes,
connection will function reliably in field service.
signal generators, meters, automatic test
equipment (ATE), or any equipment used to
perform measurements, test, or troubleshoot
CAUTION
avionic systems.
It is essential that the probe be placed against
6-3.2.1. Cleaning Versus Calibration. A problem
bare metal when taking the reading. The
rotating probe tips will create bare metal contact
common to all automatic/manual test equipment is the
when pressed into the surface.
effects dirt, dust, and lint have on equipment calibration.
Most test equipment, particularly older units, has not
6-3.1.12.1. Using a milliohm meter, such as the R1-LE
been cleaned periodically. This allows contaminants
milliohm meter, conduct an electrical resistance-bonding
to collect on components and become an integral part
test to measure resistance between antenna/equipment
of the circuit, altering circuit parameters. For example,
base and the aircraft structure. Select a scale on the
a small amount of dust around a vacuum tube socket
milliohmmeter such that the maximum allowable reading
can
affect
circuit
parameters.
These
(2.5 millohms) is near mid-range. This will to ensure
contaminantinduced changes are compensated for
maximum instrument accuracy.
during each recalibration process and can limit the
equipment's peak operating efficiency over time. Also,
6-3.1.12.2. The resistance between the antenna base/
it is easy for calibration of equipment to shift in service
equipment to be grounded and aircraft structure shall
when some of the contaminants are dislodged. Because
not exceed 2.5 milliohms.
of the effect that contaminants can have on electrical
characteristics, it is common for cleaning to significantly
6-3.2. A V I O N I C TEST EQUIPMENT. Precision
affect the electrical performance. Cleaning (and
measurement/ test equipment is required for testing,
p r e s e r v a t i o n ) is mandatory immediately after
troubleshooting, and repairing modern avionic systems.
equipment exposure to any of the following conditions:
This makes the reliability of these test systems in any
environment critical for aircraft flight and mission
a. External exposure to wet weather conditions.
essential functions. Aircraft operational requirements
often result in short turnaround repair times for
b. Internal exposure to water or any other fluid.
damaged/malfunctioning avionic equipment. This
p r o v i d e s the avionic technician little time to
c. Internal or external exposure to fire extinguishing
troubleshoot, test, and repair an avionic system.
agents.
Valuable maintenance time is lost if test equipment is
not functioning properly. A major source of equipment
d. Internal exposure to electrolyte or corrosive
malfunction is due to corrosion. The corrosion sources
deposits from batteries.
that are particularly detrimental to avionic test
equipment include:
6-17
