1、AEROSPACESTANDARDIssued 1985-12SAE AS 8042MANIFOLD PRESSURE INSTRUMENTS1.PURPOSE:This Aerospace Standard establishes the minimum safe performance standards for manifold pressure instruments, primarily for use with aircraft reciprocating engines.2.SCOPE:This Standard covers two basic types of manifol
2、d pressure instruments:Type I - Direct IndicatingType II - Remote Indicating; comprised of separate transmitter and indicator3.GENERAL STANDARDS:3.1Material:Materials shall be of a quality which experience and/or tests have demonstrated to be suitable and dependable for use in aircraft instruments.3
3、.2Workmanship:Workmanship shall be consistent with high grade instrument manufacturing practice.3.3Interchangeability:Instruments and instrument systems which are identified with the same manufacturers part or model number shall be completely interchangeable.3.4Compatibility:If components of Type II
4、 instruments are individually acceptable but require matching for proper operation, they shall be identified in a manner that will insure performance to the requirements of this Standard.3.5Accessibility of Controls:Controls, if provided, which are not normally adjustable in flight shall not be read
5、ily accessible to flight personnel when the instrument is installed in accordance with the manufacturers instructions.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 volu
6、ntary, 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 invites your w
7、ritten 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 written per
8、mission 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 Reaffirmed 2008-02AS 8042 Page 2 3.6Self-Test Provisions:Self-test provisions, if included, shall be
9、 spring-loaded or otherwise arranged to automatically return to the normal operating mode following self-testing.3.6.1In-Flight Testing:In-flight, self-test activation controls, if included, must provide a means to warn the pilot or appropriate flight crew member of this mode of operation.3.6.2Combi
10、ned Systems:If the equipment contains integral arrangements to permit pre-flight and/or in-flight self-test checks on the operation of the equipment in combination with other aircraft subsystems, a means shall be provided to deactivate any subsystem which might be adversely affected during the self-
11、test cycle.3.6.3Effect of Tests:The application of the specified tests shall not produce a condition which would be detrimental to the continued performance of the aircraft or the instrument.3.7Malfunction Indication:Means shall be provided to indicate malfunctions or failures of Type II instruments
12、 in a positive manner.3.7.1Power Failure Indication:Means shall be incorporated in the instrument to indicate when adequate electrical power (voltage and/or current of all required phases) is not being made available for proper operation of the instruments. Dial lights are considered to be self-indi
13、cating.3.7.2Remote Indicator:Means shall be incorporated to detect an internal malfunction or loss of information-valid signal from the remote source providing the information to be indicated.3.8Fail-Safe Provisions:No failure or malfunction of the instrument system shall introduce unsafe signal or
14、power effects to associated equipment.3.9Multiple Mode:When an instrument has more than one mode of operation, each mode shall be identified and means shall be provided to indicate the mode.3.10Display:3.10.1Indicating Means:The functions shall be indicated by means of one or more pointers, dials, t
15、apes, drums, digital displays or other devices. Unless otherwise specified, relative motion of the index with respect to the scale when moving elements are employed (either the index or the scale may be the moving element) shall be clockwise, up or to the right for increasing values. In a dual indic
16、ator, the pointers or other indicating means shall be clearly identified as 1 and 2 or as 3 and 4.3.10.2Graduations:The graduations shall be arranged to provide the maximum degree of readability consistent with the accuracy of the instrument.AS 8042Page 3 3.10.3Numerals:The display shall include suf
17、ficient numerals to permit quick and positive identification of each significant graduation.3.10.4Ambiguity:Appropriate means shall be provided to prevent ambiguous indications within the extremes of the operating range of the instrument.3.10.5Instrument Title:The instrument title, MANIFOLD PRESSURE
18、 or MANIF PRESS, shall be of the same approximate size but no larger than the numerals. The title may be of the same finish as the numerals.3.10.6Instrument Function:Where more than one function is displayed on a single instrument, the function name, when used, shall be of the same approximate size
19、but no larger than the numerals and/or instrument title.3.10.7Units of Measure:The units of measure (in Hg abs or cm Hg abs) shall appear on the display in lettering noticeably smaller than either the numerals or the title.3.10.8Dial Finish:Where applicable, unless otherwise specified by the user, m
20、atte white material shall be applied to graduations, numerals and pointers. Non-functional surfaces shall be dull black. The manufacturers trademark shall not appear on the dial unless in black-on-black. 3.10.9Visibility:Pointer(s) and dial markings shall be visible from any point within the frustru
21、m of a cone, the side of which makes an angle of 30 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 and shall not exceed .12 in (3.0 mm) for a single indicator an
22、d .19 in (4.8 mm) for a dual indicator.3.11Cover Glass:The cover glass of the instrument shall de clear, flat, colorless and free from flaws which would adversely affect the readability of the instrument. The total reflectance of the glass, including the integral lighting wedge, if applicable, shall
23、 not exceed 10% of the incident light. This reflectance applies over the visible light spectrum from 450 to 600 millimicrons and over an incident solid angle of 60 perpendicular to the viewing plane.3.12Integral Lighting:When integral lighting is provided, it must under normal cockpit lighting condi
24、tions make all markings within the required visibility angle easily readable. No direct light shall radiate from the instrument within an angle of 45 either side of the vertical center line of the instrument face in the horizontal plane, not above 30 to the longitudinal axis in the vertical plane.AS
25、 8042 Page 4 3.13Temperature:When installed in accordance with the manufacturers instructions, the instrument shall function over the range of ambient temperatures shown in Column A, and shall not be adversely affected by exposure to the range of temperatures shown in Column B below: 3.14Altitude:Wh
26、en installed in accordance with the instrument manufacturers instructions, the instrument shall function and shall not be adversely affected following exposure to a pressure range equivalent to -1,000 to 40,000 feet of standard altitude. The instrument shall not be adversely affected when subjected
27、to an ambient pressure of 50 in (127 cm) of Hg absolute.3.15Vibration:When installed in accordance with the manufacturers instructions, the instruments shall function and shall not be adversely affected when subjected to vibrations of the following characteristics:3.16Humidity:The instruments shall
28、function and shall not be adversely affected following exposure to any relative humidity in the range from 0 to 95% at a temperature of approximately 70C.3.17Operation:The transmitter of a Type II instrument shall be capable of operating in either the horizontal or the vertical position.3.18Pressure
29、 Stops:Underpressure and overpressure stops shall be provided and shall be designed to restrain the prime mover. The stops shall allow the pointer or other indicating means to travel beyond full scale, but there shall be no overlap of low and high stopped positions.3.19Noncorrosive Sealing:Where app
30、licable, the instrument mechanism shall be sealed from the pressure compartment by a metal diaphragm or bellows to prevent corrosive or explosive vapors from coming in contact with the mechanism.Instrument Location A BEngine or Engine Accessory CompartmentHeated Areas (Temperature Controlled)Unheate
31、d Areas-30 to 100C-30 to 70C-55 to 70C-65 to 100C-65 to 70C-65 to 70CInstrument Location HzMax. DoubleAmplitude MaximumAccel. Engine MountedWing or EmpennageFuselage5-1505-5005-500.100 in / 2.54 mm.036 in / .91 mm.036 in / .91 mm20 g105AS 8042Page 5 3.20Power Variation:The instrument, if powered, sh
32、all properly function with plus or minus 15% variation in DC voltage and/or plus or minus 10% variation in AC voltage and plus or minus 5% variation in frequency.3.21Hermetic Sealing:When hermetically sealed, the case of a Type II indicator shall be filled with an inert gas free of dust particles, a
33、nd sufficiently dry so that fogging of the indicator glass does not occur during the low temperature and fogging tests of this Standard.3.22Decompression:When installed in accordance with the manufacturers instructions, the instrument shall function and not be adversely affected following exposure t
34、o a sudden pressure decrease.3.23Outgassing:The instrument shall be so designed as to safeguard against hazards to the aircraft and crew, and/or malfunction of the instrument due to outgassing of compounds when subjected to a pressure of .50 in (12.7 mm) Hg abs for a period of two hours.3.24Fire Haz
35、ard:3.24.1The instruments shall be so designed as to safeguard against hazards to the aircraft in the 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 200C due to self-heating.3.24.2
36、Except for small parts (e.g. fasteners, grommets, knobs, seals, small electrical parts) that would not contribute significantly to the propagation of a fire, all materials used must be self-extinguishing when tested in accordance with the requirements of Federal Aviation Regulation 25.1359 (d) and A
37、ppendix F thereto, with the exception that materials tested may be configured in accordance with Paragraph (b) of Appendix F or may be configured as used.3.25Explosion Category:The instrument component, when intended for installation either in uninhabited areas of non-pressurized aircraft or in non-
38、pressurized areas of pressurized aircraft, shall not cause an explosion when operated in an explosive atmosphere.3.26Radio Interference:The instruments shall not be the source of objectionable interference, under operating conditions at any frequencies used on the aircraft, either by radiation or fe
39、ed, in electronic equipment installed in the same aircraft.3.27Case Ground:If the instrument case is of metal and if it has an electrical connector, one of the pins shall be connected to the case. This may be the same pin used for the cold or common side of the input power. 3.28Magnetic Effect:The m
40、agnetic effect of the instruments shall not adversely affect the performance of other instruments installed in the same aircraft.AS 8042 Page 6 3.29Pressure Extremes:The instruments shall not be adversely affected by exposure to pressures of 2.0 in (5.1 cm) abs and 5.0 in (12.7 cm) Hg in excess of t
41、he full scale reading.3.30Identification:The following shall be legibly and permanently marked on the instrument or the nameplate attached thereto:Name of instrumentManufacturers part numberManufacturers serial number or date of manufactureSAE ASFAA TSO, when issuedAircraft identification, if applic
42、ableRange, on transmitters of Type II instrumentsElectrical rating, if applicableManufacturers name4.MINIMUM PERFORMANCE UNDER STANDARD CONDITIONS:4.1Test Conditions:4.1.1Atmospheric Conditions:Unless otherwise specified herein, all tests required by this Standard shall be made at an atmospheric pre
43、ssure of approximately 29.92 in Hg (1013.2 mb), an ambient temperature of approximately 25C and a relative humidity of not greater than 85%. When tests are conducted with the pressure or temperature substantially different, allowance shall be made for the variation from the specified conditions.4.1.
44、2Vibration to Minimize Friction:Unless otherwise specified herein, all tests may be conducted with the instrument subjected to a vibration of .002 to .005 in (.05 to .13 mm) double amplitude at a frequency of 25 to 33 Hz.4.1.3Power Conditions:Except as otherwise specified herein, all tests shall be
45、conducted at the power rating recommended by the manufacturer.4.1.4Position:Except as otherwise specified herein, all tests shall be conducted with the instrument in its normal operating position.4.1.5Test Medium:The medium used for applying pressure during the tests shall be air or nitrogen.4.1.6Pr
46、essure Standard:Direct-reading instruments and transmitters of Type II instruments shall be calibrated against an absolute pressure standard known to be accurate within .03 in (.08 mm) Hg.4.1.7Electrical Standards:Transmitters of Type II instruments shall be read by a synchro angle position indicato
47、r known to be accurate within .3. Indicators of Type II instruments shall be set by a synchro or angle generator known to be accurate within .3. Pressure versus angular scaling shall be specified by the manufacturer.AS 8042Page 7 4.2Insulation Resistance:The insulation resistance of Type II instrume
48、nts measured at 200 volts DC for 5 seconds between all electrical circuits (except those internally grounded) connected together and the metallic case shall be not less than 5 megohms. Insulation resistance measurements shall not be made for circuits where the potential will appear across elements s
49、uch as windings, resistors, capacitors, etc., since this measurement is intended only to determine the adequacy of insulation.4.3Overpotential Tests:A Type II instrument shall not be damaged by application of test potential between electrical circuits and between electrical circuits and the metallic case. The test potential shall be a sinusoidal voltage of a frequency of 50 to 400 Hz with an RMS value of 5 times the maximum circuit voltage, or per Paras 4.3.1 or 4.3.2 as applicable. The potential shall start from zero and be increased
