1、AEROSPACESTANDARDAS431REV.BIssued 1960-03Revised 1996-09FOREWORDChanges in the revision are format/editorial only.1. SCOPE:This SAE Aerospace Standard (AS) covers three basic types of true mass flow indicating instruments. Each may consist of an indicator, transmitter and other auxiliary means such
2、as a power supply or amplifier as required.1.1 Purpose:This Aerospace Standard establishes the essential minimum safe performance standards for True Mass Fuel Flow Instruments primarily for use with turbine powered, subsonic transport aircraft, the operation of which may subject the instruments to t
3、he environmental conditions specified in Section 3.3.2. APPLICABLE DOCUMENTS:The following publications form a part of this document to the extent specified herein. The latest issue of SAE publications shall apply. The applicable issue of other publications shall be the issue in effect on the date o
4、f the purchase order. In the event of conflict between the text of this document and references cited herein, the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained.2.1 SAE Publications:A
5、vailable from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001.ARP461TRUE MASS FUEL FLOW INSTRUMENTSSAE 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 i
6、ts 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 invites your written comme
7、nts 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 written permission of S
8、AE. 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.orgReaffirmed 2008-02SAE AS431 Revision B- 2 -2.2 NTIS Publications:Available from NTIS, Springfield, VA 22161.NACA
9、Report 12353. GENERAL REQUIREMENTS:3.1 Materials and Workmanship:3.1.1 Materials: Materials shall be of a quality which experience and/or tests have demonstrated to be suitable and dependable for use in aircraft instruments.3.1.2 Workmanship: Workmanship shall be consistent with high-grade aircraft
10、instrument manufacturing practice.3.2 Identification:The following information shall be legibly and permanently marked on the instrument or attached thereto:a. Name of instrumentb. SAE, AS431c. Manufacturers part numberd. Manufacturers serial number or date of manufacturee. Manufacturers name and/or
11、 trademarkf. Rangeg. Ratingh. Explosion category3.3 Environmental Conditions:The following conditions have been established as minimum design requirements. Tests shall be conducted as specified in Sections 5, 6, and 7.3.3.1 Temperature: When installed in accordance with the instrument manufacturers
12、instructions, the instrument shall function over the range of ambient temperatures listed in Column A below and shall not be adversely affected by exposure to the range of temperatures listed in Column B below:TABLE 1Instrument Location A BPower Plant Accessory CompartmentPressurized AreasNon-pressu
13、rized or External Areas-30 to 150 C-30 to 50 C-55 to 70 C-65 to 150 C-65 to 70 C-65 to 70 CSAE AS431 Revision B- 3 -3.3.2 Altitude: When installed in accordance with the instrument manufacturers instructions, the instrument shall function from sea level up to the altitudes and temperatures listed be
14、low. Altitude pressure values are per NACA Report 1235.The instrument shall not be adversely affected following exposure to extremes in ambient pressure of 50 and 3 inches Hg absolute, respectively.3.3.3 Vibration: When installed in accordance with the instrument manufacturers instructions, the inst
15、rument shall function and shall not be adversely affected when subjected to vibrations of the following characteristics:3.3.4 Humidity: The instrument shall function and shall not be adversely affected following exposure to any relative humidity in the range from 0 to 95% at any temperature up to 70
16、 C.TABLE 2Instrument Location Altitude Feet TemperaturePower Plant Accessory CompartmentPressurized AreasNon-pressurized or External Areas60,00015,00060,00080 C50 C40 CTABLE 3Instrument Locationon AirframeCyclesPer SecondMaximumDoubleAmplitudeMaximumAccelerationNacelle and NacelleMounts, Wings, Empe
17、nnageand Wheel WellsFuselageForward of Spar AreaCenter of Spar AreaAft of Spar AreaVibration Isolated RackInstrument Panel5-10005-5005-1000( 5-500(500-1000 - 5 g5-1000( 5-30( 30-10000.036 inch0.036 inch0.036 inch0.036 inch0.030 inch0.020 inch-10 g2 g4 g7 g1.0 g-0.25 gSAE AS431 Revision B- 4 -3.4 Exp
18、losion Category:The instrument component, when intended for installation either in uninhabited areas of non-pressurized aircraft or in non-pressurized areas of pressurized aircraft, shall not cause an explosion when operated in an explosive atmosphere. The component shall meet the requirements appli
19、cable to the explosion category below. Specifically, any instrument component which can be an ignition source and is intended for installation in an area in which combustible fluid or vapor may result from abnormal conditions, e.g., fuel line leakage, shall meet the requirements of Category I. If th
20、e intended location is an area where combustible fluid or vapor can occur during normal operation, e.g., fuel tank, the instrument component shall meet the requirements of Category II, listed below:3.5 Fire Hazard:The instrument shall be so designed to safeguard against hazards to the aircraft in th
21、e event of malfunction or failure, and the maximum operating temperature of surfaces of any instrument component contacted by combustible fuel or vapor shall not exceed 200 C due to self-heating.3.6 Radio Interference:The instrument shall not be the source of objectionable interference, under operat
22、ing conditions at any frequencies used on the aircraft, either by radiation or feedback, in electronic equipment installed in the same aircraft as the instrument.TABLE 4Category Definition RequirementIIIIIIIVExplosionproofed: case not designedto preclude flame or explosionpropagation.Explosionproofe
23、d: case designed topreclude flame or explosionpropagation.Hermetically SealedInstrument not capable of causingan explosion.Paragraph 7.13.1Paragraph 7.13.2Paragraph 6.3.7.7Shall not be capableof producing a capacitiveor inductivespark of more than 0.2millijoules of energyor a contact spark ofmore th
24、an 4.0 millijoulesof energy.SAE AS431 Revision B- 5 -3.7 Magnetic Effect:The magnetic effect of the indicator shall not adversely affect the performance of other instruments installed in the same aircraft.4. DETAIL REQUIREMENTS:4.1 Indicating Method:One of the following methods of indication shall b
25、e employed. A single instrument may be employed embodying the features of both the Type I and Type II instruments.4.1.1 Type I Instruments: Rate of fuel flow shall be indicated by means of one or more moving pointers or dials and/or digital counter. Relative movement of the pointer with respect to t
26、he dial shall be clockwise for increasing rate of flow.4.1.2 Type II Instruments: Fuel consumed or quantity remaining shall be indicated by means of a digital counter or one or more moving pointers or dials.4.1.3 Type III Instruments: Rate of fuel flow shall be indicated by means of one or more movi
27、ng pointers, dials, or counters. Relative movement of the pointer with respect to the dial shall be clockwise for increasing rate of flow.Fuel consumed or quantity remaining shall be indicated by means of a digital counter or one or more moving pointers or dials.4.2 Display Markings:4.2.1 Finish: Un
28、less otherwise specified by the user, matte white material shall be applied to all major graduations, numerals, and indication means. Non-functional surfaces and markings shall be durable dull black.4.2.2 Graduations: Major graduations shall be used at intervals not to exceed 10% of full scale value
29、.4.2.3 Numerals: The display shall include sufficient numerals to permit quick and positive identification of each graduation. Numerals shall distinctly indicate the graduation to which each applies.4.2.4 Instrument Title: The instrument title when used shall be of the same approximate size, but no
30、larger than the numerals. The title may be of the same finish as the numerals. The units of measure shall appear on the dial in lettering noticeably smaller than either the numerals or title.4.2.5 Visibility: The indicating means and all markings shall be visible from any point within the frustum of
31、 a cone the side of which makes an angle of at least 30 degrees with the perpendicular to the dial and the small diameter of which is the aperture of the instrument case. The distance between the dial and the cover glass shall be a practical minimum.SAE AS431 Revision B- 6 -4.3 Power Variations:All
32、instruments shall function properly with 15% variation in the DC voltage and/or 10% variation in AC voltage and 5% variation in frequency. When the accuracy of the instrument is dependent upon the frequency regulation of the aircraft AC power, the manufacturers recommendations shall be followed to o
33、btain the specified performance.4.4 Hermetic Sealing:When hermetically sealed, the case shall be filled with an inert gas, free of dust particles, and sufficiently dry so that fogging of the indicator glass does not occur during the low temperature and fogging tests of this AS.4.5 Synchro Requiremen
34、ts:The synchro requirements should be in accordance with the conditions specified in ARP461 as applicable.4.6 Additional Output Signals:If required, additional sources of output signals, e.g., synchros, linear transformers, potentiometers, etc., may be included in the system to provide information t
35、o computers or to other equipment.4.7 Flow Direction:The direction of flow through the transmitter shall be permanently and legibly marked thereon.4.8 Fuel Characteristics:The system shall be designed for operation with turbine engine fuels (JP4, JP5, JP6), for operation with kerosene type fuels, an
36、d fuels including 30% aromatics.4.9 Safety Provisions:4.9.1 Fuel Flow During Malfunction: In case of malfunctioning during flight, each transmitter shall permit adequate fuel to flow either by means of an automatic by-pass or a mechanism which cannot offer a deleterious restriction to flow.4.9.2 Fla
37、me Resistance: The flowmeter transmitter shall be flame resistant, i.e., it shall not support combustion to the point of propagation of a flame after removal of the ignition source.SAE AS431 Revision B- 7 -5. TEST CONDITIONS:5.1 Atmospheric Conditions:Unless otherwise specified herein, all tests req
38、uired by this AS shall be conducted at an atmospheric pressure of approximately 29.92 inches of Mercury and at an ambient temperature of approximately 25 C and relative humidity not exceeding 85%. When tests are conducted with the atmospheric pressure or the temperature substantially different from
39、these values, allowance shall be made for the variation from the specified conditions.5.2 Vibration (To Minimize Friction):Unless otherwise specified, all tests for performance may be conducted with the instrument subjected to a vibration of 0.001 inch maximum double amplitude at a frequency of 10 t
40、o 60 cycles per second. The term double amplitude as used herein indicates the total displacement from positive maximum to negative maximum.5.3 Vibration Equipment:Vibration equipment shall be such as to allow vibration to be applied along each of three mutually perpendicular axes of the instrument.
41、5.4 Power Conditions:Unless otherwise specified, all tests shall be conducted at the power rating recommended by the manufacturer.5.5 Position:Unless otherwise specified, all tests shall be conducted with the instrument mounted in its normal operating position.5.6 Test Fuel:Unless otherwise specifie
42、d, the fuel used in test shall be Grade JP4 fuel. However, a noninflammable or higher flashpoint fluid of relatively equivalent properties may be used to reduce imminent fire hazard.6. INDIVIDUAL PERFORMANCE REQUIREMENTS:All instruments, transmitters and indicators shall be subjected to tests by the
43、 instrument manufacturer to demonstrate specific compliance with this AS, including the following requirements where applicable:6.1 Scale Error at Room Temperature:SAE AS431 Revision B- 8 -6.1.1 Transmitter: The transmitter scale error shall be determined at all the flow rates deemed necessary to de
44、monstrate compliance with the controlling purchaser requirements specification. This test shall be conducted by subjecting the instrument first to increasing rates of flow, then to decreasing rates of flow. With the rate of flow increasing, the rate shall be brought up to, but shall not exceed the r
45、ate specified to give the desired reading, and with the rate of flow decreasing, the rate shall be brought down to but shall not fall below the rate specified to obtain the desired reading. The error at each flow point shall not exceed the tolerances listed in Table 5 and Table 6. The difference bet
46、ween the reading on increasing rate of flow and the reading on decreasing rate of flow shall not exceed 1/2% of full scale reading.6.1.2 Indicator: The indicator scale error shall be determined at all major graduations. Two readings shall be taken - the first before, and the second after the instrum
47、ent is tapped. The difference between the first and second readings shall not exceed 1/2% of full scale. The second reading shall not deviate from the ideal value in excess of the tolerances shown in Table 5 and Table 6. In addition, the minimum tolerance shall be consistent with the readability of
48、the instrument.6.1.3 Auxiliary Means: Auxiliary power supplies or intermediate devices shall be tested at room temperature in accordance with the manufacturers recommendations.6.2 Dielectric:Ungrounded instruments or grounded instruments prior to connection of internal ground wire shall be tested by
49、 either the method of inspection of paragraph 6.2.1 or 6.2.2.6.2.1 Insulation Resistance: The insulation resistance measured at 200 volts DC for 5 seconds between all electrical circuits connected together and the metallic case shall not be less than 5 megohms. Insulation resistance measurements shall not be made 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.6.2.2 Overpotential Tests: Equip
