Using modern digital microprocessor technology to build avionics systems helped to significantly improve its functionality and mobility. Despite this, microprocessor systems are very sensitive to changes in voltage and static electricity. Every separate LRU should be well protected from the effects of these factors to ensure correct operation.
Great significance in the design LRU given Electromagnetic Interference (Electromagnetic Interference - EMI).
Electromagnetic Interference - the ability of electronic devices to operate simultaneously in actual use with the required quality when exposed to unintentional interference created not cause harmful interference to other electronic devices and systems.
LRU Electromagnetic Interference types
- EMI LRU radio devices placed not on board the aircraft (eg, ground radars and communications equipment);
- EMI LRU with other radio devices and onboard avionics systems and radio devices used by passengers during the flight (computers, cell phones, gaming devices, iPods and other portable devices).
In addition, LRU should be protected from the effects of lightning and different types of physical effects:
- Changes in temperature,
- Air pressure
- Various chemicals (fuel oil) and others.