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1、AEROSPACE STANDARD AS8021 Issued1981-03 Reaffirmed 2008-02 Minimum Performance Standard for Direction Instrument, Non-Magnetic (Gyroscopically Stabilized) 1.PURPOSE: This Aerospace Standard (AS) defines minimum performance requirements under standard and environmental conditions for Gyroscopically S
2、tabilized Non-Magnetic Direction Instruments for use in aircraft. 2.SCOPE: This document establishes the minimum requirements for design and qualification of equipment identified as Gyroscopically Stabilized Non-Magnetic Direction Instruments. 3.GENERAL REQUIREMENTS: 3.1Operation of Controls: The op
3、eration of controls intended for use during flight, if any, in all possible position combinations and sequences shall not result in a condition whose presence or continuation would be detrimental to the continued performance of the equipment. 3.2Accessibility of Controls: Controls which are not norm
4、ally adjusted in flight shall not be readily accessible to flight personnel, when the equipment is installed in accordance with the manufacturers instructions. 3.3Compatibility of Components: If the equipment components require matching for proper operation, they shall be identified in a manner that
5、 will provide for proper matching. The instructions furnished by the manufacturer must contain data detailing these limitations. SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is en
6、tirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefrom, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE inv
7、ites your written comments and suggestions. Copyright 2008 SAE International All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior
8、written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: 724-776-4970 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE AS8021 - 2 - 3.4Fire Resistance: Except for small parts (such as knobs, fasteners, se
9、als, grommets and small electrical parts) that would not contribute significantly to the propagation of a fire, all materials must be self-extinguishing when tested in accordance with the requirements of Federal Aviation Regulation 25.1359 (d) and Appendix F thereto, with paragraph (b) of Appendix F
10、 or may be configured as used. 3.5Interchangeability: Instruments and components which are identified with the same manufacturers part number shall be interchangeable. 3.6Malfunction Indication: Integral means shall be provided to indicate failures and/or the existence of the following conditions: (
11、a)Gyro in fast erection mode, required of electrical instruments except manually caged indicators with automatic release. (b)Gyro operating at speed below the minimum designated by the manufacturer for the instrument to meet the performance requirements herein. The requirement applies to electrical
12、and remotely operated instruments. Additionally, the indicator or display of the repeating or remote indicating type of gyroscopically stabilized instrument shall be provided with means to indicate the following failures: (c)Loss of synchro excitation (d)A mechanical obstruction in the indicator dia
13、l drive mechanism (e)Primary power loss to the indicator or display (f)Servo Amplifier power loss (g)Electrical failure in the servo drive motor phases The indicating means shall indicate the failure or malfunction in a positive and conspicuous manner. 3.7Instrument Cover Glass Reflectance: The tota
14、l reflectance of the instrument cover glass including the integral lighting wedge, if applicable, shall not exceed 10 percent of the incident light. This reflectance applies over the visible light spectrum from 450 nanometers to 600 nanometers, and over an incident solid angle of 60 degrees perpendi
15、cular to the viewing plane. SAE AS8021 - 3 - 3.8Indicating Method: One of the following methods of indication shall be employed: Method IRotating dial display with fixed datum line. The line shall rotate counter-clockwise for right turns. Method II Horizontal scale display with fixed datum line. The
16、 graduations shall move to the left for right turns. 3.9Operating Limits: The instrument shall indicate heading throughout the 360 degree scale range. During dives, climbs, and banks of up to at least 55 degree displacement from level attitude, the instrument shall remain functional; however, the he
17、ading error involved through the gimbal system need not be corrected. 3.10 Dial Markings: 3.10.1 Graduations: The indicators shall be provided with degree graduations at intervals not to exceed five (5) degrees, with major graduations every ten (10) degrees and with numerals at intervals not greater
18、 than 30 degrees, except that the 0, 90, 180, and 270 degrees positions may be marked N, E, S, and W, respectively. 3.10.2 Visibility: Index and dial markings shall be visible from any point within the upper half of a frustum of a cone, the side of which makes an angle of at least 30 degrees with th
19、e perpendicular to the dial and the small diameter of which is the aperture of the instrument case. At least two numerals shall be simultaneously visible. 3.11 Caging Provisions: Unless the gyro assembly has restricted freedom of operation in the pitch and roll axes, a means shall be provided for ca
20、ging and/or releveling the gyro. A means shall be provided to indicate when the gyro is caged, except when it is not possible to leave the gyro in the caged condition. 3.12 Course Setting Provisions: A means shall be provided for manually setting the directional indicator to any heading desired. -,-
21、,- SAE AS8021 - 4 - 4.MINIMUM PERFORMANCE REQUIREMENTS UNDER STANDARD TEST CONDITIONS: 4.1Starting: Rated instrument performance rotor speed shall be achieved within three minutes after normal power is applied for both air and electric operated instruments. By application of 50 percent of rated vacu
22、um or pressure for air operated instruments and 80 percent of rated voltage for electrically operated instruments, the gyro rotor shall start and continue to rotate. If the instrument incorporates a gyro speed monitoring device which provides a positive indication when the gyro speed is below that n
23、ecessary to meet instrument performance, the starting time may exceed three minutes, but shall not be greater than five minutes. 4.2Roll, Pitch and Yaw: The instrument shall be mounted on a test platform which is adjusted to oscillate in roll, pitch and yaw, with a total amplitude of 3 degrees about
24、 each axis, at a frequency of 5 to 7 oscillations per minute while reversing the direction of rotation every 6 revolutions. With the platform level, and the gyro operating at equilibrium speed and uncaged, the dial reading shall be noted. The platform shall then be started in its roll, pitch and yaw
25、 movement. At the end of a ten minute period the oscillation shall be stopped, the platform realigned to its starting position, and the instrument dial reading noted. The amount of drift of the dial in either direction during the ten minute test period shall not exceed 4 degrees. This test shall be
26、run four times with the instrument case rotated 90 with respect to the outer gimbal between each test. 4.3Heading Stability: The instrument shall be mounted on a turn table, tilted 54 (1) degrees from the vertical and the reading noted. The turn table shall be rotated one complete revolution about i
27、ts axis at 360 (30) degrees per minute and the drift of the dial shall not exceed two degrees. The test shall be repeated rotating the turn table in the opposite direction. 5.MINIMUM PERFORMANCE REQUIREMENTS UNDER ENVIRONMENTAL CONDITIONS: Unless otherwise specified herein, the procedures applicable
28、 to a determination of the performance of directional instruments under environmental conditions are set forth in Radio Technical Commission for Aeronautics (RTCA) Document No. DO-160, entitled “Environmental Conditions and Test Procedures for Airborne Electronic/Electrical Equipment and Instruments
29、“, dated February 1975. Performance tests specified after subjection to test environments may be made after exposure to several environmental conditions. The order of tests shall be in accordance with paragraph 3.2, page 4, of DO-160. The test procedures specified or referenced are satisfactory for
30、use in determining the performance of directional instruments under standard and extreme environmental conditions. Alternate approved test procedures that provide equivalent results may be used. As many instruments as deemed necessary to demonstrate that all instruments will comply with the requirem
31、ents of this paragraph, shall be tested in accordance with the manufacturers recommendations. -,-,- SAE AS8021 - 5 - 5.1Performance Standard for Use During Environmental Tests: The following performance standard shall be used when performance testing during an environmental test is required: (a)Ther
32、e shall be no more than five degrees drift in either direction during a ten minute period. Roll, pitch, and yaw motion is not required for this test. 5.2Temperature - Altitude - Humidity: (a)Low-Temperature - The instrument shall be subjected to the tests of DO-160, paragraph 4.4. During the test, t
33、he instrument shall operate electrically and mechanically and the requirements of paragraph 5.1 of this Standard shall be met. Following the test, the requirements of paragraph 4.0 of this Standard shall be met at standard conditions. (b)High Temperature - The instrument shall be subjected to the te
34、sts of DO-160, paragraph 4.5.1 and 4.5.2. During the test, paragraph 4.5.1, the instrument shall operate electrically and mechanically and there shall be no evidence of materials such as potting and sealing compounds exuding or dripping from the instrument. When subjected to the tests of paragraph 4
35、.5.2, the instrument shall operate electrically and mechanically and the requirements of paragraph 5.1 of this Standard shall be met. Following the test, the requirements of paragraph 4.0 of this Standard shall be met at standard conditions. (c)Altitude - The instrument shall be subjected to the tes
36、ts of DO-160, paragraphs 4.6.1, 4.6.2, and 4.6.3. During the test, paragraph 4.6.1, the instrument shall operate electrically and mechanically and the requirements of paragraph 5.1 of this Standard shall be met. After being subjected to the tests of paragraph 4.6.2, the requirements of paragraph 4.0
37、 of this Standard shall be met at standard conditions, and after being subjected to the tests of paragraph 4.6.3, the requirements of paragraph 4.0 shall be met. (d)Humidity - The instrument shall be subjected to the tests of DO-160, paragraph 6.0. After the instrument is subjected to the appropriat
38、e tests of paragraph 6.0, it shall meet the requirements of paragraph 4.0 of this Standard at standard conditions. 5.3Shock: The instrument shall be subjected to the tests of DO-160, paragraphs 7.1 and 7.2. (a)After the instrument is subjected to the tests of paragraph 7.1, it shall meet the require
39、ments of paragraph 4.0 of this Standard under standard conditions. (b)Following the tests of paragraph 7.2, the instrument or dummy load shall have remained in its mounting and no parts of the instrument or its mounting base become detached and free of the shock tested equipment. -,-,- SAE AS8021 -
40、6 - 5.4Vibration: The instrument shall be subjected to the tests of DO-160, paragraph 8.2. During the test it shall operate electrically and mechanically and the requirements of paragraph 5.1 shall be met. Following the test, the requirements of paragraph 4.0 of this Standard shall be met at standar
41、d conditions. 5.5Power Input: (a)Normal Electrical Input Variation Test 1. The instrument shall be subjected to the tests of DO-160, paragraph 16.3.1. During the test, it shall meet the requirements of paragraph 5.1 of this Standard. 2. The instrument shall be subjected to the tests of DO-160, parag
42、raph 16.3.2. During the test, it shall meet the requirements of paragraph 5.1 of this Standard. (b) Abnormal Electrical Input Variations Test 1. The instrument shall be subjected to the tests of DO-160, paragraph 16.3.3. During the test, it shall operate electrically and mechanically, and degradatio
43、n of performance is permissible. There shall be no evidence of the presence of fire or smoke during the test of paragraph 16.3.3.2. After returning to normal input it shall meet the requirements of paragraph 4.0 of this Standard. 2. The equipment shall be subjected to the tests of DO-160, paragraph
44、16.3.4. During the test, it shall work electrically and mechanically, with degraded performance. There shall be no evidence of the presence of fire or smoke during the test of paragraph 16.3.4.2. After returning to normal power input it shall meet the requirements of paragraph 4.0 of this standard.
45、3. The equipment shall be subjected to the tests of DO-160, paragraph 16.3.5. After returning to normal power input, it shall meet the requirements of paragraph 4.0 of this Standard. 5.6Conducted Voltage Transients: The instrument shall be subjected to the tests of DO-160, paragraph 17.0. (a)Intermi
46、ttent Transients - Following the tests of paragraph 17.3.2 or paragraph 17.4.1, as appropriate, the instrument shall meet the requirements of 4.0 of this Standard. (b)Repetitive Transients - When the instrument is subjected to the tests of paragraph 17.4.2, it shall meet the requirements of paragrap
47、h 5.1 of this Standard. -,-,- SAE AS8021 - 7 - 5.7Conducted Audio Frequency Susceptibility Test: The instrument shall be subjected to the tests of DO-160, paragraph 18.0. During the tests, it shall meet the requirements of paragraph 5.1 of this Standard. 5.8Audio Frequency Magnetic Field Susceptibil
48、ity: The instrument shall be subjected to the tests of DO-160, paragraph 19.0. During the tests, it shall meet the requirements of paragraph 5.1 of this Standard. 5.9Radio Frequency Susceptibility and Emission Tests: The instrument shall be subjected to the tests of DO-160, paragraphs 20.0 and 21.0.
49、 During the tests, it shall meet the requirements of paragraph 5.1 of this Standard. 5.10 Magnetic Effect: The instrument shall be tested in accordance with DO-160, paragraph 15.0. 5.11 Explosion: Instruments which are to be marked Explosion, Category E, shall be tested in accordance with DO-160, paragraph 9.0. 5.12 Waterproofness: Instruments which are to be marked Wa