EUROCAE ED-90A PDF

PURPOSE AND SCOPE

The purpose and scope of this Users Guide is to provide additional information and clarification on the test procedures. To this end, ED-14D, Change 1,Section 20, which is included at Appendix C, should be read in conjunction with this document.

The purpose of testing to Section 20 of ED-14D is to ensure that equipment will continue to operate within its performance specification when the equipment and its interconnecting wiring are exposed to levels of RF current and RF fields of defined levels. Two test procedures are used. First: the injection of RF currents by means of specially designed injection probes into the interconnecting bulk cables or individual power lines of the equipment. Second: electric field illumination of the equipment and its interconnecting wiring by means of an antenna placed 1 metre away or by the use of a reverberation chamber. The drawings provided in Section 20 could be difficult to interpret and this report, in some cases, contains some different presentations of these figures.

The tests are designed to simulate the effects of high power onboard or external RF transmitters eg radar or communications transmitters.

New categories have been introduced in Change 1 of Section 20 of ED-14D directly related to the aircraft HIRF environments. These new categories can be used to aid in the certification of Level A Display systems. (as defined in AC/AMJ 1309). Certification of such systems under JAA requirements allows the use of fixed test levels related to the external HIRF environment. The use of these new categories is discussed in the appropriate sections of this document. Although these new categories are adequate to aid in the certification of Level A Display systems additional installation requirements are needed. To this end Section 7 of the HIRF Users Guide (EUROCAE Document ED107) should also be studied. The procedures in ED-14D are however suitable without modification for equipment/systems performing Level B & C functions and suitable categories are available in Section 20 and will be discussed further.

The definitions for the various function levels are defined in AC/AMJ 20.1317 as:

1. Level A: Electrical and electronic systems whose failure would cause or contribute to a failure of function resulting in a catastrophic failure condition for the aircraft.

2. Level B: Electrical and electronic systems whose failure would cause or contribute to a failure of function resulting in a hazardous/severe-major failure condition for the aircraft.

3. Level C: Electrical and electronic systems whose failure would cause or contribute to a failure of function resulting in a major failure condition for the aircraft.