1、BRITISH STANDARD AEROSPACE SERIES BS G 257-3:2004 Design of electromagnetic hazard protection of civil aircraft Part 3: Guide to clearance and testing ICS 33.100.01; 49.060 BS G 257-3:2004 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 Ma
2、rch 2004 BSI 31 March 2004 The following BSI references relate to the work on this British Standard: Committee reference ACE/66 Draft for comment 97/720195 DC ISBN 0 580 43407 9 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Commi
3、ttee ACE/66, Aerospace electromagnetic compatibility of aircraft, upon which the following bodies were represented: Civil Aviation Authority (Airworthiness Division) ERA Technology Ltd. Federation of the Electronics Industry Ministry of Defence Society of British Aerospace Companies Amendments issue
4、d since publicationBS G 257-3:2004 BSI 31 March 2004 i Contents Page Committees responsible Inside front cover Foreword ii Introduction 1 1S c o p e 1 2 Normative references 1 3 Certification process 2 4 Functional criticality 4 5 Certification rationale 4 6 Certification plan 6 7T e s t p l a n 6 8
5、 Equipment level testing 8 9 Power supply disturbances 9 10 Inter-system EMC 9 11 HIRF 13 12 System susceptibility to lightning 27 13 Certification report 32 Annex A (informative) Requirements of the airworthiness authorities 33 Bibliography 37 Figure 1 Route to certification 3 Figure 2 Routes to co
6、nformity 18 Figure 3 Routes to conformity Expanded view of steps 7 to 9 20 Table 1 Functional criticality 5 Table 2 Test requirements 15 Table 3 Aircraft system function criticality 17BS G 257-3:2004 ii BSI 31 March 2004 Foreword This part of BS G 257 has been prepared by Technical Committee ACE/66,
7、 and provides information to engineers involved in all levels in the hardening of civil aircraft and their systems against electromagnetic hazards (EMH). BS G 257, Design of electromagnetic hazard protection of civil aircraft, is published in three parts: Part 1: Guide to the theory and threats; Par
8、t 2: Guide to protection; Part 3: Guide to clearance and testing. The way to effectively ensure that a complex electronic system will be resilient to the effects of EMH is to impose a visible and tightly controlled design, procurement and development process to control electromagnetic compatibility
9、(EMC) issues, from the very beginning of a project. The way in which this is achieved is very much a matter of policy within individual companies. This part outlines the main aspects of an effective EMC design and control process. The testing required to achieve EMC clearance by demonstrating that a
10、n aircraft is free of critical EMC problems is a process that starts as early as possible and continues throughout the development of the aircraft. The testing can be divided up into four types; component testing, rig testing, testing during assembly and whole aircraft testing. The degree of testing
11、 will depend on the criticality of the system, with systems performing functions such as flight and engine control being subject to more strenuous requirements than systems of a lower criticality. WARNING This British Standard calls for the use of substances and/or procedures that may be injurious t
12、o health if adequate precautions are not taken. It refers only to technical suitability and does not absolve the user from legal obligations relating to health and safety at any stage. Wherever tests involve the radiation of radio frequency (RF) energy, attention is drawn to all the relevant safety
13、procedures; including those concerning biological radiation hazards, fuel vapour explosion hazards and the inadvertent initiation of electro-explosive devices (EEDs). This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct applic
14、ation. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 37 and a back cover. The BSI copyright displayed in this document indicates when the document
15、 was last issued.BS G 257-3:2004 BSI 31 March 2004 1 Introduction In the past, aircraft were flown using mechanical systems to control the engines and to move the flying control surfaces. Many of the functions previously performed solely by mechanical systems have either been assisted or replaced by
16、 electronic circuits. Likewise, many of the cockpit instruments which previously were mechanical in nature have been integrated into electronic instrument systems. As aircraft systems become increasingly complex, aircraft are dependant upon electronic-based systems to provide not only basic flight a
17、nd engine control functions, but also flight data displays and navigation. Increased reliance upon electronic equipment and systems makes protection against EMHs a prime requirement, with the number of EMHs which can potentially result in interference with normal system operation rising rapidly. As
18、a result, a complete aircraft EMC test is complicated and needs careful thought and planning. The system modes which need to be tested have to be carefully considered, as do the failure criteria and the means by which the system behaviour is monitored during testing so the electromagnetic behaviour
19、of the aircraft and its systems is not invalidated. EMHs for civil aircraft include the direct and indirect effects of lightning, static charging, high intensity radiated fields (HIRF) from external emitters, the on-board RF environment due to the aircrafts own transmitters and the self-generated RF
20、 and electrical induced transients. However, this standard only covers the clearance and testing for the indirect effects of lightning, HIRF and inter-system EMC. 1 Scope This part of BS G 257 is written to assist engineers working at all levels within companies involved in the aircraft industry to
21、meet the applicable EMH requirements. This part of BS G 257 is intended to assist engineers with planning the certification process and to ensure that the correct processes are applied to the writing of procedures and plans, and that the presently recognized methods of test are appropriately used. T
22、he guide does not contain mandatory requirements, only guidance to assist in the solution of design problems. The guide does not cover: a) the protection of the airframe against the structurally damaging, direct effects of lightning; b) the design of communication systems in order to produce interfe
23、rence free operation since it is felt that these aspects of RF systems design are covered in adequate detail in other documents e.g. Minimum Operational Performance Specification (MOPS). The problems of interaction between radio receivers and transmitters are still an important aspect of EMC problem
24、s; c) electrostatic discharge. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this part of BS G 257. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. F
25、or undated references, the latest edition of the publication referred to applies. BS G 257-1, Design of electromagnetic hazard protection of civil aircraft Part 1: Guide to the theory and threats. BS G 257-2, Design of electromagnetic hazard protection of civil aircraft Part 2: Guide to protection.B
26、S G 257-3:2004 2 BSI 31 March 2004 3 Certification process 3.1 Planning 3.1.1 Aircraft systems should operate safely during and after exposure to any EMHs in order that safe take- off, flight and landing are achieved. To ensure safe operation, systems should be assessed to determine how an aircraft
27、reacts to an encounter with an electromagnetic effect. The outcome of this evaluation is an EMH criticality list which identifies the EMH criticality of each piece of equipment. The purpose of the criticality list is to optimize the EMC design and test effort. 3.1.2 The interactions which should be
28、considered as requiring testing for clearance include the following: a) interaction between systems which unintentionally produce and/or are susceptible to electromagnetic interference; b) interaction between systems which intentionally transmit electromagnetic radiation and/or are susceptible (e.g.
29、 the ILS and VHF systems, the fuel gauging system and HF transmission); c) interaction between the external electromagnetic environment and the potentially susceptible systems (e.g. the induced effects of lightning on fly-by-wire systems). 3.2 Route to certification 3.2.1 In general, the process des
30、cribed in Figure 1 applies to all certifications. Clauses 4 to 13 of this guide describe in greater detail the major elements of the route to certification against the effects of electromagnetic hazards. 3.2.2 A number of philosophies exist to achieve the certification of systems installed in aircra
31、ft. The choice of which is most appropriate depends on the criticality of the function performed by the system and the amount of electromagnetic data available (see Clause 4). Before any further progress can be made towards certification, a definition of the effects of the failure of all functions s
32、hould be made and agreed with the certification authorities. 3.2.3 Having agreed the criticalities of the functions to be certified, it is then possible to adopt a philosophy that will result in the most cost effective route to certification. It is necessary to consider whether a whole aircraft test
33、 is required, or if it is possible to determine the data needed to demonstrate adequate immunity by other means, such as analysis, equipment tests or similarity (see Clause 5). 3.2.4 Both internal and external environments should be considered when producing a certification plan (see Clause 6). 3.2.
34、5 Testing at both aircraft (see Clause 11) and equipment (see Clause 8) level is appropriate for the clearance of some elements of the total certification process. This should follow an agreed test plan (see Clause 7) which should cover all aspects of the electromagnetic environment within which the
35、 functions being certified are located (see Clauses 10 to 12). 3.2.6 Having obtained all the data needed for the agreed test plans, a certification report should be produced (see Clause 13).BS G 257-3:2004 BSI 31 March 2004 3 Figure 1 Route to certification Establish certification rationale Agree wi
36、th authorities Agree with authorities Agree with authorities No No No Yes Yes Yes Produce certification plan Produce certification report Gather evidence Certification granted Define functional criticalityBS G 257-3:2004 4 BSI 31 March 2004 4 Functional criticality 4.1 General 4.1.1 Early in the pro
37、ject design phase, the effect of system failures should be assessed. This normally takes the form of a Functional Hazard Assessment (FHA) which identifies the effects of the failure modes of the equipment being installed and classifies them in their functional and operational terms. This document pr
38、ovides the basis for the full System Safety Assessment (SSA) which analyses the causes of failures leading to the effect in the FHA. The output from the assessment is that the functional failures are classified as one of catastrophic, hazardous, severe-major, major or minor. 4.1.2 EMH effects are un
39、ique because of their common-mode effect on system failures, that is where all elements of a particular sub-system are affected simultaneously. Thus the FHA should be extended to ensure that common-mode failures are taken into account. 4.1.3 An aircrafts operating phases should be considered since t
40、he classification of a function failure may change dependant upon the phase of flight the aircraft is in. For example, a failure in the automatic flight control system (AFCS) might be insignificant when the aircraft is cruising but the same failure when the aircraft is on an approach could be signif
41、icant. 4.2 Assessment of criticality 4.2.1 Conformity with the appropriate airworthiness regulation is required for any system which can cause, or contribute to, an effect upon the safety of flight of the aircraft. The SSA is based on an FHA which considers only the effects of the identified failure
42、s. The effects of an encounter with, for example, HIRF should be assessed in a manner which allows the determination of the degree to which the aircraft and/or its systems may be influenced with respect to safety of flight. The operation of systems, separately and in combination with and/or in relat
43、ion to other systems, should be addressed in this respect. The assessment should include all modes of normal operation and of failures and their subsequent effect upon the aircraft, considering the stage of flight and operating conditions and the awareness of the crew to the failure. Levels of prote
44、ction for electrical and electronic systems are established dependant upon the system failure condition category (see Table 1). 4.2.2 The system failure condition category should be assessed by performing an FHA during the certification process, and should be approved by the appropriate airworthines
45、s authority. Since the FHA defines the functional criticality of the system(s) under consideration, it leads to a definition of the level of immunity required by each system with respect to electromagnetic hazards. 4.2.3 For a complete definition of failure condition categories, refer to the applica
46、ble regulations and guidance material, for example Joint Aviation Authorities advisory material AMJ 25.1309 1. The failure condition categories listed in Table 1 are derived from this guidance material and are included to assist in the use of this document. 5 Certification rationale 5.1 General 5.1.
47、1 The rationale adopted for any particular function will be dependant upon the FHA, described in Clause 4. In all cases, the work should consider the effects of HIRF, both direct and indirect effects of lightning and the compatibility with on-board systems. It is recommended that the guidance in the
48、 appropriate advisory material is always followed. 5.1.2 Where the aircraft is wholly new or contains modifications that are significantly different electromagnetically from the previously certified standard, it is important that a valid appraisal of its EMC is performed. The approach adopted should
49、 be fully discussed in the Certification Plan (see Clause 6). 5.1.3 Depending on the maturity of the aircraft and the available certification data, it could be possible to achieve certification by means of similarity or by the use of existing test data. Alternatively, analytical methods could be more cost effective than test if a fully verified modelling system is available. This may be dealt with in a number of ways as described in 5.2, 5.3, 5.4 and 5.5.BS G 257-3:2004 BSI 31
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