《BS 2G 117-1975.pdf》由会员分享,可在线阅读,更多相关《BS 2G 117-1975.pdf(10页珍藏版)》请在三一文库上搜索。
1、BRITISH STANDARD AEROSPACE SERIES BS 2G 117: 1975 (Superseding BS G 117) Specification for Pressure-driven airspeed indicators UDC 629.7.054845 852 Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:00:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2G 117:1975 This British Standard, having
2、been approved by the Aerospace Industry Standards Committee, was published under the authority of the Executive Board on 31 October 1975 BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference ACE/30 Draft for comment 71/39032 DC ISBN 0 580 08894 4 Foreword
3、This revision of BS G 117:1949 has been prepared to provide an up-to-date statement of the requirements for airspeed indicators in which the presentation is driven directly by a differential pressure-measuring mechanism, the two pressures being aircraft pitot and static pressures. A British Standard
4、 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 of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an
5、inside front cover, pages i and ii, pages 1 to 4 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. Amendments issued since publication Amd. No.DateComments Licensed
6、Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:00:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2G 117:1975 BSI 11-1999i Contents Page ForewordInside front cover 1Scope1 2References1 3Definition1 4Unit of measurement1 5General construction1 6Particular requirements1 7Tests1 Appendix A Serviceab
7、ility tests4 Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:00:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii blank Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:00:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2G 117:1975 BSI 11-19991 1 Scope This British Standard specif
8、ies the general design requirements and test procedures for airspeed indicators operated directly by the aircraft pitot and static pressures. It relates to indicators with ranges partly or wholly up to 800 knots. 2 References This standard makes reference to the following British Standards: BS 3G 10
9、0, General requirements for equipment for use in aircraft. BS 2G 101, General requirements for aircraft indicators. BS G 199, Tables relating pressure to altitudes, airspeeds, and Mach numbers for use in aeronautical instrument design and calibration. The latest issues of these standards shall be us
10、ed. 3 Definition For the purposes of this standard the term “airspeed indicator” denotes an instrument used on aircraft to measure the pitot-static pressure difference calibrated in terms of speed. The speed indicated is that speed relative to the air which the aircraft would have to fly in standard
11、 sea level conditions to obtain the measured pitot-static pressure difference. 4 Unit of measurement The unit of measurement shall be the knot based on the international nautical mile of 1852 m (exactly). 5 General construction 5.1 The design, construction and presentation of the indicator shall com
12、ply with the relevant requirements of BS 3G 100 and BS 2G 101 and with the test requirements of clause 7 of this standard. 5.2 The preferred cases are the type 3 and type 6 cases shown in BS 2G 101. 6 Particular requirements 6.1 Detailed construction 6.1.1 The indicator shall contain a differential
13、pressure-measuring mechanism driving a form of display complying with the requirements of the individual specification. 6.1.2 Any pointer scale used in the presentation, which need not be linear, shall comply with the requirements of the individual specification. 6.1.3 The pointer stop shall not be
14、a scale marking. The pointer shall move off the stop to the first scale mark in accordance with the requirements of the individual specification. 6.1.4 Pointers and any settable indices shall comply with the requirements of BS 2G 101. Preferably, the setting controls for indices should be in the bot
15、tom left-hand corner of the indicator. 6.1.5 The indicator shall be capable of withstanding a differential pressure 10 % greater than the maximum pressure range. 6.1.6 The indicator shall be capable of withstanding a reverse pressure (i.e. static pitot) of 10 mbar1). 6.1.7 The pitot and static conne
16、ctions shall comply with the requirements of BS 2G 101 and shall be indelibly marked P and S respectively. 6.1.8 If a limit pointer is fitted it shall comply with the requirements of BS 2G 101. 6.2 Calibration. The calibration of the indicator shall be in accordance with the pressure/speed relations
17、hip defined in Table 2 of BS G 199. 7 Tests 7.1 General 7.1.1 Tests shall be made to prove compliance with all the requirements of this British Standard. It is neither intended nor recommended that complete tests be made on every indicator supplied. Three kinds of tests are specified as follows: a)
18、type tests, to be made on representative samples to prove the design; b) production routine tests, to be made on all indicators manufactured in accordance with the standard; c) production quality tests, to be made on samples as specified in the individual specification. 7.1.2 For the guidance of use
19、rs, Appendix A recommends minimum tests to verify the serviceability of indicators manufactured in compliance with this British Standard. 7.1.3 Vibration not exceeding 0.2 g may be applied to the indicators during performance testing, except during the friction test specified in 7.2.3. NOTEVibration
20、 of this order is attainable with a total amplitude of 0.04 mm at a frequency of 50 Hz. 1) 1 mbar = 102N/m2= 0.1 kPa Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:00:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2G 117:1975 2 BSI 11-1999 7.1.4 Unless otherwise specified, tests shall b
21、e made at a temperature of 20 5 C. 7.1.5 The reference standard for the differential pressure shall be accurate, with corrections, to within 0.15 % of pressure reading or 0.15 mbar, whichever is the greater. 7.1.6 With the exception of the damping test in 7.2.6, the rate of change of differential pr
22、essure applied to the indicator during testing shall not exceed the equivalent of 100 pointer movement per second at any point on the indicator range. 7.2 Type tests 7.2.1 Ranging accuracy and hysteresis test 7.2.1.1 With the indicator in the normal position with the dial upright, the indicator shal
23、l be calibrated at both increasing and decreasing pitot pressures at the following points: a) at the lowest scale mark; b) at every 50 knot and 100 knot point up to 300 knots; c) at every 100 knot point to the maximum of the range: d) at the maximum range point, if not an exact “100”. Other calibrat
24、ion points may be required by the individual specification. 7.2.1.2 At 100 knots and above, the airspeed errors shall not exceed 2 knots or 1 % of airspeed, whichever is the greater. For speeds below 100 knots the accuracy requirements shall be stated in the individual specification. 7.2.1.3 If fitt
25、ed, limit pointers shall conform to the tolerances specified in the individual specification. 7.2.2 Position test. The change in reading when the indicator is turned in any direction through 90 from the normal position shall not exceed half the ranging tolerance appropriate to any point on the scale
26、. 7.2.3 Friction. At two points, one in the middle and one in the lower range of the indicator, pitot pressure shall be applied to bring the indication approximately to the desired reading without overshoot and then shall be held constant, the indicator being carefully isolated from vibration. Two r
27、eadings shall be taken, the first with the instrument undisturbed and the second after the instrument has been tapped or vibration has been applied. The difference between the two readings shall not exceed 2 knots. 7.2.4 Temperature. At temperatures of 20 C and + 50 C the errors in airspeed shall no
28、t exceed 1.5 times the tolerances specified in 7.2.1. After subjection to temperatures of 62 C and + 85 C the indicator shall not be deranged nor shall the calibration errors be outside normal tolerances. The indicator shall satisfy the requirements of the test specified in 7.2.10 b). NOTEOn a numbe
29、r of modern aircraft the temperature behind the instrument panel will be above the + 20 C temperature at which tests are made in accordance with this specification, and normal performance may be required in such circumstances at + 40 C. Where required, this will be stated in the individual specifica
30、tion and the performance of the indicator at such temperature has to be declared. 7.2.5 Overload test. The indicator shall remain within calibration after subjection to the overload pressures specified in 6.1.5 and 6.1.6 for a period of 5 min. 7.2.6 Damping test. The damping of the indicator shall b
31、e such that, when pressure equivalent to two-thirds of the full scale reading is applied to the pitot connection and suddenly released, the pointer returns past the minimum scale reading in not more than 1 s and not less than 0.5 s. 7.2.7 Vibration test. Vibration tests shall be made in accordance w
32、ith the requirements of BS 3G 100-2-3.1, in particular 3.4 or B.4.2. The accuracy of the indication shall comply with the requirements of 7.2.1 of this standard and the pointer oscillation shall be within the overall tolerances, unless otherwise stated in the individual specification. 7.2.8 Accelera
33、tion test. The indicator shall be subjected to acceleration tests in accordance with the requirements of BS 3G 100-2, as required by the individual specification. 7.2.9 Additional environmental tests. The indicator shall be subjected to additional environmental tests specified in BS 3G 100-2, as req
34、uired by the individual specification. The required functioning tests shall be ranging accuracy at three points spaced equally to cover the range. 7.2.10 Leakage test. This test shall be conducted as follows. a) Pitot pressure shall be applied to the indicator to move the indication to the maximum o
35、f the calibrated range and the indicator shall then be sealed off. After the internal temperature settles, the indication shall not show any decrease in the ensuing minute. b) With the pitot and static connection connected to atmosphere, the indicator shall comply with the requirements of 3.10 of BS
36、 2G 101. Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:00:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2G 117:1975 BSI 11-19993 7.2.11 Pointer freedom test. Pointers or indices shall be checked at all positions within their range to ensure that no fouling with the main indication tak
37、es place. 7.3 Production routine tests. Each indicator shall satisfactorily fulfil the requirements of the tests specified in 7.2.1., 7.2.2, 7.2.3, 7.2.5, 7.2.10 and 7.2.11. 7.4 Production quality tests. Sample indicators, selected as specified in the individual specification, shall satisfactorily f
38、ulfil the requirements of the tests specified in 7.2.4, 7.2.6, 7.2.7 (resonance search only), 7.2.8 and 7.2.9. Any significant change in resonance frequency or any new resonance frequencies shall be recorded. Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:00:42 GMT+00:00 2006, Uncontrolle
39、d Copy, (c) BSI BS 2G 117:1975 4 BSI 11-1999 Appendix A Serviceability tests The minimum tests recommended to verify the serviceability of indicators manufactured in compliance with this British Standard are as follows. A.1 Ranging accuracy and hysteresis test (7.2.1). A.2 Friction test (7.2.3). A.3
40、 Leakage test (7.2.10). A.4 Pointer freedom test (7.2.11), if relevant. Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:00:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI blank Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:00:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2G 11
41、7: 1975 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsible for preparing British Standards. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter. Revisions British S
42、tandards are updated by amendment or revision. Users of British Standards should make sure that they possess the latest amendments or editions. It is the constant aim of BSI to improve the quality of our products and services. We would be grateful if anyone finding an inaccuracy or ambiguity while u
43、sing this British Standard would inform the Secretary of the technical committee responsible, the identity of which can be found on the inside front cover. Tel: 020 8996 9000. Fax: 020 8996 7400. BSI offers members an individual updating service called PLUS which ensures that subscribers automatical
44、ly receive the latest editions of standards. Buying standards Orders for all BSI, international and foreign standards publications should be addressed to Customer Services. Tel: 020 8996 9001. Fax: 020 8996 7001. In response to orders for international standards, it is BSI policy to supply the BSI i
45、mplementation of those that have been published as British Standards, unless otherwise requested. Information on standards BSI provides a wide range of information on national, European and international standards through its Library and its Technical Help to Exporters Service. Various BSI electroni
46、c information services are also available which give details on all its products and services. Contact the Information Centre. Tel: 020 8996 7111. Fax: 020 8996 7048. Subscribing members of BSI are kept up to date with standards developments and receive substantial discounts on the purchase price of
47、 standards. For details of these and other benefits contact Membership Administration. Tel: 020 8996 7002. Fax: 020 8996 7001. Copyright Copyright subsists in all BSI publications. BSI also holds the copyright, in the UK, of the publications of the international standardization bodies. Except as per
48、mitted under the Copyright, Designs and Patents Act 1988 no extract may be reproduced, stored in a retrieval system or transmitted in any form or by any means electronic, photocopying, recording or otherwise without prior written permission from BSI. This does not preclude the free use, in the cours
49、e of implementing the standard, of necessary details such as symbols, and size, type or grade designations. If these details are to be used for any other purpose than implementation then the prior written permission of BSI must be obtained. If permission is granted, the terms may include royalty payments or a licensing agreement. Details and advice can be obtained from the Copyright Manager. Tel: 020 8996 7070. Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:00:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI
链接地址:https://www.31doc.com/p-3730558.html