Avionics News November 2014 - 60

AVIONICS TECHNICIAN CERTIFICATIONS
Continued from page 59

operational checks and troubleshooting, transmission
lines, and antennas. Moreover, the requirements include
specific knowledge of aviation VHF communications,
HF communications and satellite communications.
Regarding satcom, the panel of experts brought together
by the NCATT recognized SiriusXM as an important factor
in many aircraft. Many of us learned about satcom systems
designed for business and dispatching use, but not so much
for broadcasting. The endorsement test gives technicians
incentive to study SiriusXM.
All of the endorsements address safety. In the
case of the RCS, the endorsement test may ask about
protection of personnel from physical contact injuries
from antennas, radio frequency radiation hazards and
electromagnetic field hazards. In addition, though
airborne weather radar is not a communication system,
communication technicians may be working around
weather radar-equipped aircraft; therefore, technicians
are required to demonstrate knowledge of the dangers
inherent in working near an operating radar system.
You must know the lay of the communication
frequency landscape for the RCS exam. In other words,
you should know the frequency bands designated by
the FCC and how signals propagate within those bands.
You also must have an understanding of modulation
modes of operation and how they are used. Included
in the landscape knowledge is a requirement to know
the frequencies used and number of channels, if
applicable, and modes of operation of various avionics
communication systems.
For the most part, you must demonstrate knowledge
of radio receiver and transmitter theory to the block
diagram level. There is some overlap with the AET
certification exam, so earning an RCS endorsement
requires you to be familiar with tuning circuits,
amplifiers, oscillators and filters. Furthermore, you
will need to demonstrate knowledge of modulators and
demodulators.
Don't forget to review antenna and transmission line
theory. Not only should you know basic antenna theory,
but also the type of antenna used for each system, how
they are installed and where they would be mounted
on an airframe. The endorsement requires technicians
to be familiar with the transmission lines used in
communication systems and the various means of
making connections.
The RCS endorsement exam requires technicians to
understand how communication systems are integrated
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into the aircraft. As result, you should be familiar with
bus requirements, audio systems, control heads (panels)
and auto tuning from flight management systems.
As one would expect, knowledge of troubleshooting
is an important factor for the RCS exam; therefore, you
must have a familiarity with the test equipment used to
ramp test communication systems, the types of tests to
make on the flight line and how to mitigate electrical
noise problems.
Dependent Navigation Systems
Endorsement
This is the second of the bread and butter systems.
Why? It's because virtually any aircraft on which we can
make a living has at least one of each. Although there are
some avionics-free airplanes flying, they aren't putting
bread and butter on any of our tables.
Like the RCS, this endorsement requires safety
knowledge. But if you passed the communication test
recently, you are unlikely to require further study.
The DNS standard requires you to demonstrate a
thorough understanding of the antenna types in use.
Review mounting systems on light aircraft, business
jets, transport category aircraft and military aircraft.
Moreover, you should review antenna installation,
bonding, tuning and troubleshooting. At the very least,
technicians should be able to differentiate between VOR,
DME, marker, GPS and ADF antennas. It wouldn't hurt
to read over a few antenna specification sheets.
You must be familiar with coaxial and triaxial cables
and the various types of connectors used in the industry.
The NCATT standard completes the antenna section with
a reference to FAA Advisory Circular 43.13-1B CHG 1,
chapter 12.
Review the Earth coordinate system along with the
concept of great circle navigation. You must be familiar
with GPS theory of operation, including GPS segments,
almanacs and databases. GPS comes with a whole bucket
full of abbreviations, and you will need to be familiar
with all of them.
The DNS standard requires you to understand how
the GPS integrates with other systems. The standard
mentions autopilots, FMS, INS, IRS, altimetry systems,
annunciators and displays.
The GPS section of this standard has a slight overlap
with the ANS endorsement. This makes sense, since an
IRS-equipped aircraft will use great circle navigation
and have the system closely integrated with the GPS and
the FMS.
You must be familiar with theory behind the VOR
system, including the radio and modulating frequencies
Avionics News November 2014

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