1、BRITISH STANDARD AEROSPACE SERIES BS G259:1996 ISO9662:1994 Aircraft equipment Environmental and operating conditions for airborne equipment Humidity, temperature and pressure tests ICS 49.020.00BSG259:1996 This BritishStandard, having been prepared under the directionof the Engineering SectorBoard,
2、 was published underthe authority oftheStandards Board and comes into effect on 15June1996 BSI01-2000 The following BSI references relate to the work on this standard: Committee reference ACE/58 Draft for comment92/77495 DC ISBN 0 580 25628 6 Committees responsible for this BritishStandard The prepa
3、ration of this BritishStandard was entrusted to Technical Committee ACE/58, Environmental and operating conditions for aircraft equipment, upon which the following bodies were represented: Civil Aviation Authority Federation of the Electronics Industry Ministry of Defence Society of British Aerospac
4、e Companies Society of Environmental Engineers Amendments issued since publication Amd. No. Date CommentsBSG259:1996 BSI 01-2000 i Contents Page Committees responsible Inside front cover National foreword ii Introduction 1 1 Scope 1 2 Normative reference 1 3 Conventions 1 4 Test applications 1 5 Tes
5、t procedures 1 6 Test facilities 3 Figure 1 Humidity/temperature/pressure profile for test Nos.1 and2 4 List of references Inside back coverBSG259:1996 ii BSI 01-2000 National foreword This BritishStandard has been prepared by Technical Committee ACE/58 and is identical with ISO9662:1994 Aircraft eq
6、uipment Environmental and operating conditions for airborne equipment Humidity, temperature and pressure tests, published by the International Organization for Standardization (ISO). NOTE 1The 1992 edition of ISO7137 to which normative reference is made has been revised and published as ISO7137:1995
7、. NOTE 2The latest edition of an Aerospace Series standard is indicated by a prefix number. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not
8、 of itself confer immunity from legal obligations. Cross-references Publication referred to Corresponding BritishStandard ISO7137:1995 BS4G229:1996 Schedule for environmental conditions and test procedures for airborne equipment (Identical) Summary of pages This document comprises a front cover, an
9、inside front cover, pagesi andii, pages1 to4, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BSG259:1996 BSI 01-2000 1 Introduction This Inter
10、national Standard is intended to apply primarily to equipment in regions of civil and transport aircraft where induced changes in atmospheric conditions result in frosting, external and internal condensation and moisture ingress. Equipment will experience these conditions as the aircraft descends fr
11、om low temperature at high altitude into a warmer atmosphere. This is particularly relevant to equipment which is not totally sealed and where the accompanying change in pressure can aggravate the effect causing ingress of moisture. 1 Scope This International Standard, which is applicable primarily
12、to civil and transport aircraft, specifies the test requirements for aerospace equipment which could be subjected to moisture ingress, frosting and condensation, resulting from the passage through atmospheric conditions of high humidity, in combination with or induced by changing temperature and pre
13、ssure. It specifies various test procedures which can be invoked when required by an equipment design and requirement specification. This International Standard permits the selection of specific test conditions and methods that define acceptance requirements for aerospace equipment which may be subj
14、ect to induced condensation and humidity. The conditions are more likely to occur in an unconditioned bay but may also occur in a conditioned bay when the equipment has a short thermal transmission path to an external airframe structure. The incidence of this form of condensation is also influenced
15、by the duty cycle of the equipment and its thermal characteristics. This test is not intended to reveal the defects ensuing from prolonged exposure to high humidity such as may occur on the ground in tropical climates, a suitable test for this environment is given in ISO7137. Also this test is not i
16、ntended to simulate the hazards of local ice formation, in which case reference should be made to the icing tests defined in ISO7137, test procedure 1.4. 2 Normative reference The following standard contains provisions which, through reference in this text, constitute provisions of this Internationa
17、l Standard. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent edition of the standard indicated below. Members of
18、 IEC and ISO maintain registers of currently valid International Standards. ISO7137:1992, Aircraft Environmental conditions and test procedures for airborne equipment (Endorsement of EUROCAE/ED-14C and RTCA/DO-160C). 3 Conventions In this International Standard, altitudes and pressures are expressed
19、 in conformity with the practice of ICAO. 4 Test applications Three different tests are specified in this International Standard and the appropriate equipment specification should state which of the following is to be applied. Test No.2 shall be invoked in instances when the appropriate test method
20、is not obvious. 4.1 Test No.1 This test applies to items whose performance could be immediately and adversely affected by moisture condensation. The method is particularly applicable to equipment of an enclosed or partially sealed construction, where the pressure change due to altitude arising from
21、one flight descent phase could induce the ingress of moisture. 4.2 Test No.2 This test applies to equipment, or equipment containing items of enclosed or partially sealed construction where the cumulative effects of condensation over a number of flight descents would be needed to adversely affect th
22、e performance of the equipment. 4.3 Test No.3 This test applies to items of open construction whose performance could immediately and adversely be affected by moisture condensation, but where the pressure changes due to altitude would have no influence. 5 Test procedures SeeFigure 1.BSG259:1996 2 BS
23、I 01-2000 5.1 Test No.1 5.1.1 Step1 Place the test item inside the test chamber at laboratory ambient conditions and make any connections necessary through the chamber wall to apply power and to monitor test item performance. Conduct a functional performance test in accordance with the equipment spe
24、cification. 5.1.2 Step2 Reduce the temperature inside the chamber at a rate not exceeding3 C/min to20 C 2 C, or to the temperature specified by the equipment specification (seeISO7137, test procedure 1.1). Allow the test item to stabilize at the specified temperature, or condition for a period defin
25、ed in the equipment specification. 5.1.3 Step3 Reduce the ambient pressure inside the chamber to represent the specified equivalent altitude over a period of15min. 5.1.4 Step4 Maintain the conditions obtained in steps2 and3 for a minimum period of30min. 5.1.5 Step5 a) With the prevailing pressure ma
26、intained, increase the temperature inside the chamber to+30 C 2 C at an approximately uniform rate over a period of1h to2h and introduce moisture to produce relative humidity of not less than95%. Ensure that frosting or condensation occurs on the surface(s) of the test item. b) Maintain this conditi
27、on for a sufficient period of time to melt all frost and ice, or until the surface temperature of the equipment reaches0 C to+5 C, then begin restoring the pressure inside the chamber to that corresponding to ground level over a period of15min to30min. NOTE 1The point of introduction of moisture dur
28、ing the temperature increase is arbitrary. However, it is important to generate an atmosphere close to saturation and in which frosting or condensation occurs on the test item, before starting to restore the ambient pressure to corresponding ground level. 5.1.6 Step6 Maintain the damp heat condition
29、s of+30 C and95% RH to100% RH for a minimum period of1h, or for a period sufficient to carry out a functional performance test, whichever is the longer (see5.1.8). 5.1.7 Step7 On completion of step6, allow the conditions inside the chamber to return to standard ambient conditions and allow the test
30、item to stabilize. Carry out a visual inspection for ingress of water if specified in the relevant equipment specification. 5.1.8 Operation of test item for test No.1 Operate the test item during exposure to the climatic cycle as required by the relevant equipment specification. Equipment required t
31、o operate throughout the flight, including takeoff, landing and taxiing (steps1 to6 inclusive), or which only has power applied during the descent phase (steps5 and6), shall be operated on a representative duty cycle during exposure to the climatic environment. Unless required by the relevant equipm
32、ent specification, equipment normally idle during the descent phase shall not be operated until the temperature and humidity inside the chamber (step6) have stabilized at+30 C and95% RH. Unless specified otherwise in either case, the conditions in step6 shall be maintained and operation of the test
33、item shall continue for a period of1h, or for a period sufficient to carry out a performance test, whichever is the longer. Power to the test item shall then be switched off. When the test item has stabilized at laboratory ambient conditions, in accordance with step7, conduct a functional performanc
34、e test in accordance with the relevant equipment specification. 5.2 Test No.2 5.2.1 Step1 Subject the test item to the procedure defined in5.1.1 to5.1.6 to constitute the first cycle. 5.2.2 Step2 Repeat the procedure of5.1.2 to5.1.6 three times to produce a total of four cycles. If specified in the
35、relevant equipment specification, either: a) allow the test item to stabilize between cycles in accordance with5.1.7 to constitute a24h cycle; or b) immediately start the next cycle following5.1.6 by returning directly to the specified low temperature. If option a) is selected, no “artificial” dryin
36、g out procedure shall be carried out between cycles.BSG259:1996 BSI 01-2000 3 5.2.3 Step3 On completion of step6 of the fourth cycle, allow the conditions inside the chamber to return to standard ambient conditions and allow the test item to stabilize. Carry out a visual inspection for ingress of wa
37、ter if specified in the relevant equipment specification. 5.2.4 Operation of the test item for test No.2 Operation of the test item should be generally in accordance with the requirements of5.1.8. If required by the relevant equipment specification, additional functional performance tests may be car
38、ried out, e.g.if option a) of step2 is selected, conduct a functional performance test towards the end of the stabilization period between climatic cycles. 5.3 Test No.3 Two alternative procedures are permitted in accordance with5.3.1 and5.3.2. Procedure B is recommended where operation of the equip
39、ment is specified during exposure. 5.3.1 Procedure A: Two chamber method a) Place the test item in a low temperature test chamber at standard ambient conditions and lower the temperature to20 C 2 C or asspecified in the relevant equipment specification at a rate not exceeding3 C/min. Allow the test
40、item to stabilize at the specified temperature, or condition for a period defined in the equipment specification. b) Transfer the test item to a humidity chamber in which the working volume has been previously conditioned at+30 C 2 C and humidity of not less than95% RH. Make the transfer as quickly
41、as possible, but in any case in a time not exceeding15min, this latter period applying only to complex equipment involving handling problems. Make any connections necessary through the chamber wall to apply power and to monitor test item performance. NOTE 2The arrangement for the transfer of the tes
42、t item between chambers requires appropriate planning in order to minimize the time that the doors and cable access ports are open and the time necessary to restore the applied environment. c) When the temperature and humidity inside thetest chamber have stabilized at+30 C and95% RH to100% RH, condi
43、tion the test item for a minimum period of1h, or for a period sufficient to carry out a functional test, whichever is the longer. d) On completion of c), allow the conditions inside the humidity chamber to return to standard ambient conditions and allow the test item to stabilize. Carry out a visual
44、 inspection for ingress of water if specified in the relevant equipment specification. 5.3.2 Procedure B: One chamber method a) Place the test item in the climatic chamber and begin the test procedure in accordance with5.3.1 a). b) Introduce heat and moisture such that the temperature inside the cha
45、mber is raised from the specified low temperature to+30 C 2 C in1h to2h. Do not allow the rate of temperature change to exceed3 C/min at any time. During this transitional period, hold the humidity close to saturation (nominally not less than95% RH). c) Condition the test item in accordance with5.3.
46、1 c). d) Allow the conditions inside the climatic chamber to return to standard ambient conditions and allow the test item to stabilize. Carry out a visual inspection for ingress of water if specified in the relevant equipment specification. 5.3.3 Operation of the test item for test No.3 Operation o
47、f the test item shall be in accordance with the requirements of the relevant equipment specification. For procedure A, it is anticipated that operation of the test item will only be required when the temperature and humidity conditions inside the chamber have stabilized. Unless otherwise specified,
48、apply power and operate the test item for1h, or for a sufficient period to conduct a specified functional performance test, whichever is the longer. For procedure B, operation of the test item shall be generally in accordance with the operating requirements for test No.1 (see5.1.8). 6 Test facilitie
49、s The test chamber required to carry out these tests is more complex and, therefore, more expensive than those necessary to apply the individual environments.BSG259:1996 4 BSI 01-2000 However, the prime purpose of the tests is to demonstrate compatibility and/or vulnerability of the test item when exposed to the aggravated conditioning which occurs during the transition from flight to ground conditions. This would not beproperly demonstrated by tests representing theindividual environments. Frosting, melting/condensation and the induced in
