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Environmental testing
Electronics are now
integral to many of the
objects we interface
with every day. As we
continue to demand more functionality and
connectivity as consumers, engineers strive to create,
design and test new products which use electronics.
Aerospace electronics is advancing at the same
astounding pace as consumer electronics. However, the
environment for a phone in your pocket or a watch on
your wrist is different than an aircraft’s operational
environment in the sky. The testing of electronics for use
in aviation applications therefore often leads the way for
other sectors. The only way to ensure safety in aviation
is through sound engineering and quality practices,
coupled with proper testing. For testing to be effective, it
must be integrated into the design process and once the
product is operational, reliably included with long term
support. The testing must be based on accepted
methods, while also keeping up with new
technologies, modes of operation and enhanced
requirements. There is no easy way or short cuts;
but the results speak for themselves, especially
when it comes to electronics.
ENVIRONMENTAL STRESSES
Engineered Testing Systems (ETS) in Indianapolis,
Indiana, is a full-service test facility for military,
aerospace, automotive and medical equipment
co-managed by Bruce Justus and Steve Golten. Much of
their work involves ESS (Environmental Stress
Screening). “ESS is a combination of vibration and
thermal exposure that is used to weed out weak parts
and workmanship problems such as poor solder joints
and misaligned parts,” says Justus.
The use of ESS has been standard for aviation for
many years, but Justus says “as the use of electronics
18 months
worst-case scenario
to solve an
intermittent fault
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becomes more
embedded, old
designs that
required strictly
mechanical tests are now being
subjected to EMC environment”. The
various requirements to be met come
from MIL-STD-810 (Env) and MILSTD
461 (EMI) for the military and RTCA
DO-160 for commercial aircraft.
Commercial equipment typically uses IEC
(International Electrotechnical
Commission), CISPR (Comité
International Spécial des
Perturbations Radioélectriques)
and FCC standards.
Justus believes that the
increase in complexity and test
methodology has extended from
aerospace and military to other
industries. “Alternators, starters, dash
components, sensors…. all have to be
qualified just like military products.”
Steve Hayes, technical director
aerospace PQT (product quality testing)
for materials testing provider Element
says that “ensuring airworthiness
encompasses many different phenomena
including environmental effects such as
vibration, altitude, temperature/humidity
extremes, EMI, effects of direct lightning,
mold growth and many other hazards.”
These threats are accentuated because
of the dramatic increase in consumer
technology brought onto aircraft and
their use during critical phases of flight.
This has led to a change in how testing is
performed. Hayes says, “Products which
are connected with the safety of the flight
must be tested for HIRF High Intensity
RF fields, but in recent years, the airline
operator is responsible for performing a
HIRF assessment.”
Airline operators will perform a HIRF
assessment at the whole aircraft level
while equipment manufacturers test at
the product and system level. This
accounts for the complexity introduced
when individual airlines change the
configuration of an aircraft, adjusting
things such as seating arrangements and
the galley’s location.
1 // The Voyager
Intermittent Fault Detector
in use with a FA-18 during
routine maintenance
2 // The device is rugged
and portable so problems
with wiring and
interconnectors can be
found in the field
MIL-
2
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