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 there
2、from, 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 m
3、ay 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)
4、 Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org ARP4741 AEROSPACE RECOMMENDED PRACTICE Issued 2008-02 Aerospace-Hydraulic Switching Valve, Pressure or Pilot Operated RATIONALE This document provides guidance for the design and qualification test requirements for s
5、witching valves. These valves are typically utilized to provide secondary hydraulic power to circuits, whose primary supply source has failed. Also included is section covering relevant “Lessons Learned”. TABLE OF CONTENTS 1. SCOPE 3 2. APPLICABLE DOCUMENTS 3 2.1 SAE Publications. 3 2.2 RTCA Publica
6、tions 4 2.3 NAS Publications 4 2.4 U.S. Government Publications 4 2.5 Federal Aviation Agency 14 CFR Regulations . 4 2.6 Other Documents 4 2.7 ASME Publications 5 3. TECHNICAL REQUIREMENTS 5 3.1 Introduction . 5 3.1.1 Schematic . 5 3.1.2 Physical Interface 7 3.1.3 System Interfaces . 7 3.2 Functiona
7、l Characteristics. 7 3.2.1 Performance 7 3.2.2 Physical Characteristics 11 3.2.3 Reliability. 11 3.2.4 Maintainability . 11 3.2.5 Environmental Conditions . 11 3.3 Design and Construction. 13 3.3.1 Materials 13 3.3.2 Processes . 13 3.3.3 Parts 13 3.3.4 Identification and Marking . 14 3.3.5 Interchan
8、geability 14 3.4 Documentation 14 3.4.1 Data. 14 3.4.2 Drawings . 14 3.5 Precedence. 14 4. QUALITY ASSURANCE . 14 4.1 General . 14 4.2 Test Responsibility 14 4.2.1 Test Conditions . 15 4.2.2 Test Fluid 15 SAE ARP4741 - 2 - 4.2.3 Test Failure . 15 4.3 Acceptance Test . 15 4.4 Qualification Test 15 4.
9、4.1 Test Specimen Schedule 15 4.4.2 Test Methods 16 4.4.3 Environmental Tests . 16 4.4.4 Performance Tests 17 4.4.5 Structural Tests. 18 5. PREPARATION FOR DELIVERY. 19 5.1 Preservation 19 5.2 Marking . 19 5.3 Cleanliness 19 6. NOTES 19 6.1 Lessons Learned 19 6.2 Key Words. 20 FIGURE 1 DIFFERENT VAL
10、VE CONFIGURATION TYPES. 6 TABLE 1 PRESSURE CLASSES. 5 TABLE 2 9 TABLE 3 ENDURANCE SPECTRUM 10 TABLE 4 LEAKAGE MEASUREMENT SEQUENCE. 10 TABLE 5 11 TABLE 6 TEST SCHEDULE 16 SAE ARP4741 - 3 - 1. SCOPE This SAE Aerospace Recommended Practice (ARP) establishes the requirements for the design, manufacture
11、, and qualification of four hydraulic switching valves used in airborne applications. Two are pressure operated, Type IA and IB and two are solenoid/pilot operated, Type IIA and IIB. They are applicable to four pressure classes 3000, 4000, 5000 and 8000 psi. The equipment as designed is intended to
12、be installed in hydraulic systems designed to AS5440 for military applications or ARP4752 and ARP4925 depending on the type of aircraft for commercial applications. Additional or refined requirements shall be contained in the detail (procurement) specification and these shall take precedence over an
13、y potentially conflicting requirements of this ARP or documents referenced by this ARP. 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 b
14、e the issue in effect on the date of 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 b
15、een obtained. 2.1 SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org. AS568 Aerospace Size Standard for O-Rings AS1241 Fire Resistant Phosphate Ester Hydraulic Flui
16、d for Aircraft ARP1383 Impulse Testing of Aerospace Hydraulic Actuators, Valves, Pressure Containers, and Similar Fluid System Components AS3121 Plug, Expansion - Aluminum, 2024-T4, Long, Standard and .010 Oversize Diameters through AS 3128 AS4059 Aerospace Fluid Power - Cleanliness Classification f
17、or Hydraulic Fluids AS4716 Gland Design, O-Ring and Other Elastomeric Seals ARP4752 Aerospace - Design and Installation of Commercial Transport Aircraft Hydraulic Systems ARP4925 Aerospace - Design and Installation of Commercial Transport Helicopter Hydraulic Systems AS4941 Aerospace - General Requi
18、rements for Commercial Aircraft Hydraulic Components AS5440 Hydraulic Systems, Aircraft, Design and Installation, Requirements for AS8775 Hydraulic System Components, Aircraft and Missiles, General Specification for AS40401 Solenoid, Electrical, General Specification for J24714 Fluid Systems - Conne
19、ctor Tubes - General Specification and Part Standard SAE ARP4741 - 4 - 2.2 RTCA Publications Available from Radio Technical Commission for Aeronautics, Inc., 1828 L Street, NW, Suite 805, Washington, DC 20036, Tel: 202-833-9339, www.rtca.org. RTCA/DO - 160 Environmental Conditions and Test Procedure
20、s for Airborne Equipment 2.3 NAS Publications Available from Aerospace Industries Association, 1000 Wilson Boulevard, Suite 1700, Arlington, VA 22209-3928, Tel: 703-358-1000, www.aia-aerospace.org. NAS 847 Caps and Plugs, Protective, Dust and Moisture Seal, General Specification for 2.4 U.S. Governm
21、ent Publications Available from the Document Automation and Production Service (DAPS), Building 4/D, 700 Robbins Avenue, Philadelphia, PA 19111-5094, Tel: 215-697-6257, http:/assist.daps.dla.mil/quicksearch/. MIL-STD-7179 Finishes, Coatings and Sealants, for Protection of Aerospace Weapons Systems M
22、IL-PRF-5606 Hydraulic Fluid, petroleum based, Aircraft, Missile and Ordnance (inactive for new design) MIL-PRF-83282 Hydraulic Fluid, Fire Resistant, Synthetic Hydrocarbon Base, Aircraft MIL-PRF-87257 Hydraulic Fluid, Fire Resistant, Low temperature, Synthetic Hydrocarbon Base, Aircraft and Missile
23、MIL-STD-704 Aircraft Electric Power Characteristics MIL-STD-810 Environmental Engineering Considerations and Laboratory Tests MIL-STD-461 Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and Equipment MIL-HDBK-5 Metallic Materials and Elements for Aerospace
24、Vehicle Structures Note: This HDBK, a long-time reference book, has been cancelled May 2004. See paragraph 2.6 for possible alternative. 2.5 Federal Aviation Agency 14 CFR Regulations Available from the regulatory and guidance website http:/rgl.faa.gov. 23.1435 Hydraulic Systems - normal airplane 25
25、.1435 Hydraulic Systems - transport airplane 27.1435 Hydraulic Systems - normal rotorcraft 29.1435 Hydraulic Systems - transport rotorcraft 2.6 Other Documents MIL-HDBK-5, referenced in section 2.4, was cancelled in May of 2004. This document is issued by the FAA as a suitable replacement. Users are
26、 cautioned to evaluate the MMPDS Handbook for their particular application before using it as a direct replacement document. The current edition of MMPDS may be obtained at www.mmpds.org or http:/projects.battelle.org/mmpds/ (not through the DAPS/ASSIST website). MMPDS Metallic Materials Property De
27、velopment and Standadization SAE ARP4741 - 5 - 2.7 ASME Publications Available from American Society of Mechanical Engineers, 22 Law Drive, P.O. Box 2900, Fairfield, NJ 07007-2900, Tel: 973-882-1170, www.asme.org. Y14.100 Engineering Drawing Practices 3. TECHNICAL REQUIREMENTS 3.1 Introduction The s
28、witching valves covered in this ARP control the flow of hydraulic power from one or more hydraulic power sources to a load or subsystem. Switching points are usually controlled by the pressure differentials between the two supply systems using electrical or hydro-mechanical means to accomplish the s
29、witching. Four types of switching valve assemblies in four different pressure classes are covered under this specification and are defined as follows: Type IA Pressure Operated Two Position Six-way Valve Type IB Pressure Operated Three Position Six-way Valve Type IIA Solenoid Controlled Two Position
30、 Six-way Valve Type IIB Solenoid Controlled Three Position Six-way Valve Pressure classes are defined as shown in the first column of Table 1. The related system, proof and burst pressures are also listed. TABLE 1 - PRESSURE CLASSES System Pressure Proof Pressure Burst Pressure Class psi (MPa) psi (
31、MPa) psi (MPa) 3000 3000 (20.7) 4500 (31.0) 9000 ( 62.0) 4000 4000 (27.6) 6000 (41.3) 12,000 ( 82.7) 5000 5000 (34.5) 7500 (51.7) 15,000 (103.4) 8000 8000 (55.2) 12,000 (82.7) 16,000 (110.3) The detail requirements shall be as defined in the detail specification. The following abbreviations are used
32、 throughout the text: P1- Primary supply pressure PR1- Primary system return pressure P2- Secondary supply pressure PR2- Secondary system return pressure PL- System or load pressure RL- System or load return R1- Primary return R2- Secondary return P - Value of Pressure differential between P1and P2
33、used for switching 3.1.1 Schematic The schematic shall be as defined in Figure 1 or in the detail specification. SAE ARP4741 - 6 - FIGURE 1 - DIFFERENT VALVE CONFIGURATION TYPES SAE ARP4741 - 7 - 3.1.2 Physical Interface 3.1.2.1 Mounting Provisions The mounting provisions shall be as defined in the
34、detail specification. 3.1.3 System Interfaces The hydraulic and electrical system interfaces shall conform to the requirements of the detail specification. All hydraulic port connections should be located on one face of the valve body in order to allow removal and/or installation of the valve withou
35、t the need to remove lines or cause damage to the tube-fitting sealing interfaces. 3.1.3.1 System Pressures The supply, return and transient pressures shall be as specified in the detail specification. 3.1.3.2 System Fluid Unless otherwise specified in the detail specification, the valves shall be d
36、esigned to operate with MIL-PRF-5606, MIL-PRF-83282 and MIL-PRF-87257 hydraulic fluid in military aircraft, and AS1241 fluid for commercial applications. 3.1.3.3 System Cleanliness and Operation in Contaminated Fluid The valve shall be designed to operate in a system having contamination levels as s
37、pecified in the detail specification. Common practice defines operation in a system with a fluid cleanliness level of class 9 per AS4059. In addition it should be specified that, the valve shall continue to operate as intended after being subjected to operation for a specified period of time with fl
38、uids contaminated to class 12 per AS4059. If testing in contaminated fluid is required, the test must be fully identified in the detail specifications. Just specifying a particular contamination level, such as AS4059 Class 9, is not sufficient since the type of contaminants is not controlled and the
39、 distribution of particles may be completely different for two fluids with the same classification. The endurance test defined in 3.2.1.3.5 can satisfy this requirement. 3.1.3.4 Electrical For Type II valves, the electrical supply shall conform to MIL-STD-704 or as specified in the detail specificat
40、ion. 3.2 Functional Characteristics 3.2.1 Performance Unless otherwise specified the performance requirements defined herein shall apply to operation under rated conditions. 3.2.1.1 Function The operation of the different types shall be as described below and as shown in Figure 1. The specific opera
41、tion shall be as defined in the following paragraphs. The value of “P“ must be defined in the specification sheet. Type IA. Normal Operation P1and R1shall be connected to PLand RLwhenever P1is equal to or greater than P2-P, or when P1and P2- are zero. Decreasing Primary Pressure P2- and R2shall be c
42、onnected to PLand RL whenever P2- is greater than P1+P. Increasing Primary Pressure with P2- and R2connected to PLPLand RLare blocked, when neither solenoid one (1) nor two (2) are energized. The valve shall switch to connect P2and R2to PLand RLwith solenoid two (2) energized. As in the Type IB unit
43、, a system integrity check can be performed while the valve is in the center position. The integrity checking circuit may, or may not, be integrated into the valve. 3.2.1.2 Rated Conditions The rated conditions define a set of standard conditions at which certain specified performance tests are to b
44、e conducted. These conditions by no means define and limit the performance envelope of the units to these conditions. 3.2.1.2.1 Pressures The system pressures, unless otherwise specified in the detail specification, shall be as follows: Supply Pressures: See Table 1: System Pressure Return Pressures
45、: Return pressures shall be as defined in the detail specification. Transient Pressures: The maximum transient pressures shall be as defined in the detail specification. Proof and Burst Pressures: See Table 1 for general guidelines. For military aircraft, the proof and burst pressures shall be per A
46、S5440. For commercial aircraft, the requirements are outlined in 23.1435, 25.1435, 27.1435 and 29.1435. The pressures shall be in accordance with the applicable FAR/JAR requirements as detailed in AS4941. Impulse Pressure: The unit shall be subjected to an impulse test in accordance with the require
47、ments of ARP1383 unless otherwise specified in the detail specification. 3.2.1.2.2 Flow The rated flow shall be defined in the detail specification. SAE ARP4741 - 9 - 3.2.1.2.3 Rated Temperature Unless otherwise specified in the detail specification, the rated temperature shall be: TABLE 2 Condition
48、 deg F (deg C) Ambient 70 +/- 20 (21.1 +/- 11.1) Fluid 120 +/- 10 (48.9 +/- 5.6) 3.2.1.3 Performance Requirements 3.2.1.3.1 Pressure Drop This pressure drop is defined as the drop from P1to R1, or P2to R2, with PLand RLlooped and shall be kept reasonably low, or as specified in the detail specificat
49、ion. Typical values range between 100 and 150 psi (690 to 1035 kPa) at rated temperature. 3.2.1.3.2 Switching Pressures The switching pressures for Type IA and IB valves shall be as defined in 3.2.1.1, using the value for the switching pressure differential specified in the detail specification. The valve shall switch positively, without interruption or hesitation in the movement of the shuttle, from the primary t
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