1、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 entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefr
2、om, 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 invites your written comments and suggestions. Copyright 2008 SAE International All rights reserved. No part of this publication may
3、 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 written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: 724-776-4970 (outside USA) F
4、ax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org AS 8003-2 -3.6 Pressure Datum: The code generator outputs shall be referenced to 29.9213 in. Hg absolute or 1013.25 millibars or 760.001 mm Hg absolute, for zero feet indication and shall supply the encoded output valu
5、es in accordance with the U.S. Standard Pressure Altitude Tables 1962. If the code generation equipment forms part of an altimeter system, the altimeters barometric setting system shall not affect the encoded outputs.3.7 Operating Range: The operation range for all pressure altitude code generating
6、devices shall start at or below -1000 feet (-304.8 metres) M.S.L. pressure altitude and shall continue to the upper pressure altitude limit as indicated on the equipment nameplate.3.8 Power Loss: If electrical power is used to operate the pressure altitude code generating equipment, means shall be i
7、ncorporated in the equipment to indicate the loss of electrical power or the effect thereof, unless the electrical power to operate the code generating equipment is supplied by an ATC Transponder which also supplies an indication of this power loss. Under the power loss condition, the equipment shal
8、l: a) Provide for the deactivation of the generated digital code outpit in a manner which removes the altitude information supplied to the ATC Transponder.b) Provide means to indicate the loss of electrical power in a positive manner.Power from the ATC Transponder as related to the generated encoded
9、 output does not require power lossindications.3.9 Encoded Altitude Return Lead, Common: The opening of the common lead or the equivalent thereto shallresult in no encoded altitude information being transmitted to the ATC Transponder. If the code generator requires its own power supply to generate t
10、he code, the circuit design shall be such that this function of opening the common lead or the equivalent thereto is not impaired.3.10 Overrange Operation: Appropriate means shall be incorporated within the code generating equipment to provide for encoded output for at least the extremes of the spec
11、ified operating range of the instrument.Overrange of the instrument shall not cause the generation of any encoded output which is within the specified operating range of the instrument.3.11 Correspondence: The pressure altitude generated encoded output shall correspond to the displayed pressure alti
12、tude indication used to maintain flight altitude to within 125 feet (38.1 metres) when the pressure datum is set for 29.921 inches of mercury absolute (1013.25 millibars or 760 mm Hg Abs.).3.11.1 For any barometric setting within the operating range of barometric settings for the pressure altitudedi
13、splay, the generated encoded output which is transmitted to the ATC Transponder shall correspond to the displayed altitude value to within 125 feet (38.1 metres) when the displayed altitude value is corrected for the difference in feet as a result of the applied barometric setting and the value of t
14、he displayed pressure altitude based on the pressure datum of 29.921 inches of mercury absolute (1013.25 millibars or 760 mm Hg Abs.).3.11.2 The requirements specified in 3.11 and 3.11.1 shall be applicable to both increasing and decreasingpressure altitude changes.NOTE: For example, if the encoded
15、output is 10,000 feet (3048 metres), the pressure altitude display (when corrected for the actual barometric setting in feet and the pressure datum) shall indicate 10,000 feet (3048 metres) 125 feet (38.1 metres) during the whole interval that the encoded output remains at 10,000 feet.3.12 Transitio
16、n Accuracy: When a transition from one encoded output to the next encoded output occurs, forboth increasing and decreasing altitude changes, the displayed pressure altitude shall be within 75 feet(22.86 metres) of the nominal pressure altitude for that transition point, corrected for the differences
17、 infeet as a result of the applied barometric setting and the value of the displayed pressure altitude based onthe pressure datum of 29.921 inches of mercury absolute (1013.25 millibars or 760 mm Hg Abs.).AS 8003-3 -3.12.1 Transition points for both the ON and OFF position for each output bit (chann
18、el) shall be checked in anincreasing altitude direction and the transition at the same points shall be checked in a decreasing altitude direction.3.12.2 Transition points for each bit (channel) shall be checked for all bits (channels) in accordance with themaximum operating altitude range defined fo
19、r the equipment.3.13 Fire Resistance: Except for small parts (such as knobs, fasteners, seals, grommets, and small electricalparts) that would not contribute significantly to the propagation of a fire, all combustible materials must be self extinguishing. When tested in an approved method, the avera
20、ge burn length must not exceed 3 inches (76.2 min) and the average flame time after removal of the flame source must not exceed 30 seconds. Drippings from the test specimen must not continue to flame for more than an average of 3 seconds after falling.4. PERFORMANCE UNDER STANDARD CONDITIONS4.1 Stan
21、dard Atmospheric Conditions: Unless otherside specified herein, all tests required shall be made atatmospheric conditions specified in paragraph 3.4 of DO-138.4.2 Attitude: Unless otherwise specified, herein, all tests shall be conducted with the instrument in its normaloperating position as defined
22、 in the manufacturers installation instructions.4.3 Performance Tests: The instrument shall be tested to demonstrate compliance with 3.8, 3.9, 3.10, 3.11and/or 3.12 as applicable to the code generating equipment.4.4. The performance tests specified above shall be conducted in accordance with the ope
23、rational requirements specified by the manufacturer in the installation instructions and the installation instructions shall specify:a) Code generator operating power requirementsb) ATC Transponder types and/or manufacturers with which the code generator shall interface (e.g., ARINC 532D) or the equ
24、ivalent to the following information:1. Minimum and maximum voltage and polarity that can be impressed on each encoded output lead.2. Minimum and maximum current impressed on each encoded output lead.3. Minimum and maximum impedance each encoded output lead will work into.4. Minimum and maximum volt
25、age to be measured between each encoded output lead and the encoder common for an ON signal output code (logical “1“).5. Maximum leakage current for (4) above.6. Maximum voltage to be measured between each encoded output lead and the encoder common for an OFF signal output code (logical “O“).7. Maxi
26、mum rate of altitude change for the code generating equipment.8. The switching bandwidth in kilocycles for proper code transmission to the ATC Transponder.9. And any other requirements which are unique to the subject code generating equipment which will affect the performance tests.AS 8003-4 -4.5 Ba
27、lance Error: If the instrument is potentially subject to balance error (mechanical balance, servo backlash, etc.), the instrument shall be tested in the following positions, and performance standards of 3.11 and 3.12 shall be met.1) Normal operating position.2) Instrument rotated clockwise and count
28、er clockwise around its X (longitudinal) axis, 90 degrees from its normal position.3) Instrument rotated clockwise and counter clockwise around its Y (lateral) axis, 90 degrees from its normal position.4) Instrument rotated around its X (longitudinal) axis, 180 degrees from its normal position.4.6 C
29、ode Output: The manufacturer of the pressure altitude code generation equipment shall determine thepresence of each required encoded output for each 100 foot encoded value to the maximum operating pressure altitude indicated on the identification plate.4.7 Magnetic Effect: The magnetic effect of the
30、 instrument shall be determined in terms of the deflection ofa free magnet, approximately 1-1/2 in. long, in a magnetic field with a horizontal intensity of 0.18 0.01 gauss when the instrument is held in various positions on an east-west line with the nearest part 12 inches from the center of the ma
31、gnet. With the instrument operating, the maximum deflection of the free magnet shall not exceed five degrees from any indicating or reference position.5. PERFORMANCE STANDARDS UNDER ENVIRONMENTAL CONDITIONS5.1 When the code generating equipment forms part of an aircraft system, such as a pressure al
32、titude indicator, an air data computer or an ATC Transponder, the code generating equipment shall meet the performance requirement specified therein for the environmental conditions specified for these aircraft systems.5.1.1 When the code generating system is independent of any aircraft system, the
33、manufacturer shall define the exact environmental conditions and/or categories of R.T.C.A. DO-138 Appendix B under which the equipment will perform to the requirements of this Standard. The applicable environmental condition and/or categories shall be specified in the manufacturers installation inst
34、ructions and/or on the equipment nameplate.5.1.2 Unless otherwise specified by the manufacturer, the measurement procedures applicable to a determination of the performance of the instruments under environmental conditions are set forth in R.T.C.A. Document DO-138 entitled “Environmental Conditions
35、and Test Procedures for Airborne Electronic/Electrical Equipment and Instruments“ dated June 27, 1968 shall apply.5.2 Environmental Categories: The code generating equipment shall be subjected to tests in accordance withthe environmental conditions to which the equipment will be subjected to and ope
36、rated within. Environmental condition and categories defined for the equipment shall be stated on the equipment nameplate in accordance with Appendix B of DO-138, or in the manufacturers installation instructions. Conditions and categories which differ from those defined in Appendix B of DO-138 shal
37、l be clearly defined in the installation instructions.5.2.1 The equipment shall be subjected to the defined environmental test conditions as per the procedures defined in R.T.C.A. DO-138 or as defined by the manufacturer for conditions and procedures which differ from R.T.C.A. DO-138 and shall meet
38、the standards as defined in paragraph sections 3.0 and 4.0 relative to performance, and shall not be damaged by being subjected to these tests. 5.2.2 Performance tests which are required after subjection to test environments may be conducted after exposure to several environmental conditions.AS 8003
39、-5 -5.3 The following list of environmental categories and conditions are considered as the minimum standardrequirements, in addition to the performance under standard conditions.a) Temperature/Altitude (categories DO-138)b) Over pressure (external to the equipment)c) Humidityd) Shock (categories)e)
40、 Vibration (categories)f) Temperature variation (categories)g) Power input variationh) Conducted voltage transienti) Electrical insulation (dielectric) (Appendix)AS 8003-6 -APPENDIX1.1 Dielectric: Ungrounded instruments, or internally grounded instruments with the internal grounds disconnected, shal
41、l be tested by the method of inspection listed in 1.1.1 and 1.1.2.1.1.1 Insulation Resistance: The insulation resistance measured at 200 volts DC for five seconds between allelectrical circuits and the metallic case shall not be less than 5 megohms. Insulation resistance measurements shall not be ma
42、de to circuits where the potential will appear across elements such as windings, resistors, capacitors, etc., since this measurement is intended only to determine adequacy of insulation.1.1.2 Overpotential Tests: The instruments shall not be damaged by the application of a test potential between ele
43、ctrical circuits, and between electrical circuits and the metallic case. The test potential shall be a sinusoidal voltage of a commercial frequency with an R.M.S. value of five times the maximum circuit voltage. The potential shall start from zero and be increased at a uniform rate to its test value
44、. It shall be maintained at this value for five seconds, and then reduced at a uniform rate to zero.Since these tests are intended to insure proper electrical insulation of the circuit components in question, these tests shall not be applied to circuits where the potential will appear across element
45、s such as windings, resistors, capacitors, etc.1.1.2.1 Hermetically sealed instruments shall be tested at five times the maximum circuit voltage up to a maximum test voltage of 200 volts R.M.S.1.1.2.2 Circuits that operate at potentials below 15 volts are not to be subjected to overpotential tests.PREPARED BYSAE COMMITTEE A-4, AIRCRAFT INSTRUMENTS
