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Environmental Testing Laboratory

Electromagnetic Compatibility

In recent years, the increased development of the electronics industries
influences the aviation industry. In particular aboard of modern civil aircraft a
wide range of communications and entertainment electronics is available to the EMC_Chamber.JPGpassenger. Consequently modern aircraft cabins contain besides electronic
systems necessary for flight, more and more devices solely for the convenience
of the passenger.

Such devices can cause a substantial increase in the electromagnetic radiation
and must therefore be subjected within the aeronautical approval to
electromagnetic compatibility (EMC) tests. The EMC guidelines give rules and
limitations of the influence of different devices from each other. A device must
function properly and reliably in its environment under certain interference
effects. At the same time it must not impose an unacceptable disturbance for its
environment.

A part of the environmental laboratory is especially designed for EMC testing.
There is an anechoic chamber and a number of special test devices that are
necessary to perform the required test, i.e. according to the RTCA/DO-160. Both,
conducted and radiated effects are analyzed. In particular, the electromagnetic
emission of a device is during the initial approval of the utmost importance, as
these devices could interfere other electronics in aircraft (i.e. avionic) that are
critical for safe flight (i.e. ILS receiver or autopilot).

 

HASS / HALT

HASS and HALT are increasingly in aviation applications. Their advantage is
given by the short-term nature of the results. Within a few days lessons can be
learned about a product that would otherwise be available only after lengthy
individual environmental tests.umweltlabor_mrz%202013_klein2.jpg

The Highly Accelerated Life Test (HALT) is a method that was originally
developed for the automotive industry. During a HALT thermal and multiaxial
mechanical loads are subjected simultaneously to a unit, which artificially
accelerate the aging of the unit. The test consists of several stages, that are
going consciously beyond the specification limits to deliberately provoke
failures. The HALT test is therefore suitable to detect weaknesses in the design
of electronic components early.
HALT is not standardized, thus HALT procedures will be tailored depending on
the test device and the product itself.

The Highly Accelerated Stress Screening (HASS) is performed with series
production units. It is based on the results of the HALT tests with much smaller
impact and shall ensure that the tracked faults during the HALT test are
remedied.

Shock & Vibration Tests

On the vibration table (shaker) in our environmental laboratory shock and
vibration tests are conducted. These tests simulate mechanical stress to which
aviation devices are exposed during their use in flight profile. That include mq2.jpgvibrations caused i.e. in engines, such as shocks and collisions, which occur
during takeoff and landing or in case of a crash.
Both types of stress do not affected only locally but globally the entire aircraft.
Thus, depending on the aircraft type and location of the device, different degrees
of load level and characteristics can be identified. These vibration profiles are
simulated by the shaker.
Relevant physical quantities in the vibration tests are the "frequency range" and
"acceleration", as well as for the impact and shock tests the variables
"acceleration", "pulse duration" and "shock profile".

The shock and vibration tests are carried out during qualification as part of a
certification process. They prove that the tested device withstands the strain of
aviation without affecting the functional operation of that device.

Temperature & Humidity Tests

With the climatic chamber of our environmental laboratory temperature and
humidity tests are conducted. These tests simulate thermal and climatic stress mq8.jpgto which aviation devices are exposed during operation in different climates and
weather conditions.
For scheduled flights operating in hot regions temperature changes of about
100 K (+40 °C on the ground and -55 °C in altitude) are not uncommon.
Temperature Variation Tests simulate these environmental conditions. Another
challenge is the combination of high temperature and high humidity, such as it
occurs in tropical regions. These conditions ar simulated by Humidity Tests.

The temperature and humidity tests during qualification as part of a certification
process proof that the tested devices function properly even under demanding
environmental impacts of aviation.

Fluids Susceptibility Tests

Depending on the location on the aircraft, a component might come into contact
with different fluids. Such fluids are i.e. cleaning fluids and drinks in the cabin,
as well as oils and hydraulic fluids for example in the landing gear. Components mq6.jpgin the wing area might come in contact with kerosene or deicing fluids.

To test the compatibility with the above-mentioned and other agents (fluids) the
Fluids Susceptibility Test is carried out. Here, either complete devices or only
their materials in the form of material samples are subjected to the test. These
tests are carried out either as a spray or optionally as an immersion test with
partially different temperatures of the fluids. A storage during or after the tests at
a temperature of +65° C provides a potentially higher susceptibility.

 

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