Environmental 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 passenger. 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.

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 vibrations 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 to 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 in 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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