1、 AEROSPACE STANDARD Aircraft Maintenance Jacks - General Requirements 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
2、 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 comments and suggestions. Copyright 2004
3、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 SAE. TO PLACE A DOCUMENT ORDER: Tel:
4、877-606-7323 (inside USA and Canada) Tel: 724-776-4970 (outside USA) Fax: 724-776-0790 Email: custsvcsae.org SAE WEB ADDRESS: http:/www.sae.org Issued 1994-07 Revised 2004-12 Superseding AS4775 AS4775 REV.A FOREWORD This document is intended to establish minimum standards, and provide a recommendati
5、on for the design, manufacture and testing of aircraft jacks; which will permit safe operation and minimize potential aircraft damage and personnel safety hazards associated with aircraft jacking operations. The jacks described in this document are intended to be used for scheduled and unscheduled a
6、ircraft maintenance, modification, repair, emergency repair, as well as functional test and general inspection of aircraft. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AS4775 Revision A - 2 -
7、 TABLE OF CONTENTS FOREWORD.1 1. SCOPE 4 2. APPLICABLE DOCUMENTS.4 2.1 SAE Publications4 2.2 International Standards - ISO.5 2.3 Industrial Publications 5 2.4 U.S. Government Publications .5 3. JACK ASSEMBLY5 4. CLASSIFICATION6 5. GENERAL DESIGN CONSIDERATIONS6 5.1 The Aircraft Interface6 5.2 Floor
8、Loading .6 5.3 Human Factors, Controls .6 5.4 General Design Criteria7 5.4.1 Materials and Components 7 5.4.2 Metals.7 5.4.3 Dissimilar Metals7 5.4.4 Workmanship .7 5.4.5 Welding 7 5.4.6 Dimensions and Tolerances.8 5.4.7 Screw Assemblies8 5.4.8 Finishes and Markings .8 5.4.9 Identification.8 5.5 Mai
9、ntainability 8 6. HYDRAULIC SYSTEM AND COMPONENT DESIGN.8 6.1 Hydraulic System .8 6.1.1 Description .8 6.1.2 Hydraulic Fluid .8 6.1.3 System Pressure9 6.1.4 Overload Protection .9 6.1.5 Air Entrapment .9 6.1.6 Auxiliary Pumps .9 6.2 Components.9 6.2.1 Pump9 6.2.2 Reservoir10 6.2.3 Jack Rams and Cyli
10、nders 10 Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AS4775 Revision A - 3 - 7. STRUCTURAL DESIGN CONSIDERATIONS.11 7.1 Jack Adapter 11 7.2 Supporting Jack Structure11 7.3 Tripod Jack Legs12
11、7.4 Tripod Jack Bracing .13 7.5 Tripod Jack Ladders and Platforms .13 7.6 Fastening Devices13 7.7 Component Selection.13 7.8 Component Maintenance.13 7.9 Reliability13 7.10 Tripod Jack Leveling 14 7.11 Parts Interchangeability14 7.12 Jack Options 14 8. TRANSPORTING AND SHIPPING15 8.1 Casters.15 8.2
12、Tow Bars15 8.3 Carrying Handles .15 8.4 Shipping .15 9. TESTING .16 9.1 First Article Design Test and Verification .16 9.1.1 Static-Proof Test 16 9.1.2 Settling Test .16 9.1.3 Endurance Test16 9.2 Production Acceptance Test 17 9.2.1 Visual Test .17 9.2.2 Operational Testing17 TABLE 1 Classification
13、of Aircraft Jacks6 FIGURE 1 Typical Hydraulic System, Hydraulic Aircraft Jack .9 FIGURE 2 Tripod Leg Design12 Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AS4775 Revision A - 4 - 1. SCOPE: Thi
14、s document covers the general requirements for hydraulic aircraft jacks. It can be applied to tripod, unipod, and axle jacks that may be used on open ramp areas as well as in the aircraft hanger. Throughout this Aerospace Standard, the minimum essential criteria are identified by the key word “shall
15、”. Recommended criteria are identified by use of the key word “should”. Deviation from recommended criteria should only occur after careful consideration and thorough service evaluation have shown alternate methods to provide an equivalent level of safety. The term “vertical load” throughout this Ae
16、rospace Standard is defined as the force imposed on the aircraft jack at the airframe jack point. 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 publicati
17、ons shall be 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 exem
18、ption has been obtained. 2.1 SAE Publications: Available from: SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001. ARP490 Electro hydraulic Flow-Control Servo valves ARP598 The Determination of Particulate Contamination in Liquids by the Particle Count Method ARP1247 General Requirements for Aer
19、ospace Ground Support Equipment, Motorized and Non-Motorized AS33559 Adapter Aircraft, Jacking Point J514 Hydraulic Tube Fittings J517 Hydraulic Hose J533 Flares for Tubing AMS 2404 Plating, Electroless Nickel AMS 5560 Standard Steel Hydraulic Tubing Copyright SAE International Provided by IHS under
20、 license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AS4775 Revision A - 5 - 2.1 (Continued): AMS-QQ-C-320 Plating, Chromium (Electrodeposited) AMS-QQ-P-416 Plating, Cadmium (Electrodeposited) 2.2 International Standards - ISO: Available from: http:
21、/www.iso.org. ISO 1464 Aerospace - Tripod jacks - Clearance Dimensions 2.3 Industrial Publications: Available from: American Welding Society, 550 N.W. LeJune Rd., Miami, FL 33126 or http:/www.aws.org. AWS (American Welding Society) D1.1 Structural Welding Code - Steel 2.4 U.S. Government Publication
22、s: Available from: http:/assist.daps.dla.mil/quicksearch. MIL-PRF-5606H Hydraulic Fluid, Petroleum Base, Aircraft and Ordnance Available from: http:/www.osha.gov. OSHA Occupational Safety the internal leakage of the pump shall not exceed a rate of 5.0 cm3/h. e. Operate at all temperatures ranging fr
23、om -40 to +54 C (-40 to +130 F). f. 200 cycles of raising and lowering the rated capacity. g. The dust, rain, snow, ice, temperature, and other environmental conditions normally expected in service. 5.4.1 Materials and Components: The material and components used in the manufacture of the jack shall
24、 be commercially available whenever possible. They shall be appropriate for the application and the environment they will be subjected to. All components shall be arranged for maximum ease of operation and maintenance. 5.4.2 Metals: Metals shall be corrosion resistant or treated for the environment
25、they will encounter in storage or normal use. Suitable steel complying with ASTM, AMS, or AISI standards shall be used. 5.4.3 Dissimilar Metals: Unless specifically protected against electrolytic corrosion, dissimilar metals shall not be used in intimate contact with each other. 5.4.4 Workmanship: T
26、he jack assembly shall be fabricated, assembled, and finished to the highest current manufacturing standards. Particular attention shall be given to freedom from blemishes, burrs, and sharp edges, accuracy of fabricated parts, alignment of assemblies, and tightness of fasteners. 5.4.5 Welding: Where
27、 welding or brazing is used in the manufacture of the jack assembly, the process shall be in accordance with the highest commercial standards and D1.1 Structural Welding Code of the American Welding Society. All welded joints shall be free from cracks, oxide inclusion, and injurious porosity. Copyri
28、ght SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AS4775 Revision A - 8 - 5.4.6 Dimensions and Tolerances: Dimensions and tolerances not specified shall be as close as is consistent with good commercial
29、shop practices. Where they may affect the interchangeability, operation, or performance of the jack, they shall be held or limited accordingly. 5.4.7 Screw Assemblies: All assembly screws and bolts shall be tight, with a minimum of two threads showing beyond the nut. Certain screw assemblies are an
30、exception such as the tripod cylinder head to leg fasteners. 5.4.8 Finishes and Markings: The assembly shall be finished with paint that is resistant to fire resistant hydraulic fluids commonly used in commercial aircraft. All jacks shall be clearly and permanently marked with their rated capacity.
31、All jacks with tow bars shall be clearly marked: “TOWING SPEED - 5 MPH “ (or “8 km/h” as applicable). 5.4.9 Identification: All jacks shall be permanently identified with the manufacturers name, the model number and serial number. 5.5 Maintainability: The jack shall be designed and constructed to pr
32、ovide the following: a. A minimum number of parts consistent with performance and reliability. b. A minimum necessary amount of training and time for assembly, disassembly, troubleshooting, maintenance, and servicing. c. A minimum disturbance to other parts or components while performing adjustments
33、, servicing, maintenance or replacement of components. d. A minimum amount of general and special purpose tools and equipment to perform adjustments, servicing, maintenance or replacement of components. 6. HYDRAULIC SYSTEM AND COMPONENT DESIGN: 6.1 Hydraulic System: 6.1.1 Description: The hydraulic
34、system consist of a hydraulic cylinder, pump (manual, air operated, and/or electric powered), manual release valve, safety relief valve, check valves, reservoir, and all necessary tubing, hoses, and fittings as shown in Figure 1. It shall be equipped as a minimum with a single self-contained, hand o
35、perated hydraulic pump or when applicable dual or two-speed hand operated pumps. 6.1.2 Hydraulic Fluid: The hydraulic system shall be designed to operate with MIL-PRF-5606 or equivalent commercially available hydraulic fluids. Copyright SAE International Provided by IHS under license with SAENot for
36、 ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AS4775 Revision A - 9 - 6.1.3 System Pressure: For design purposes, the optimum hydraulic pressure shall be 20,700 kPa (3000 psi) for tripod and unipod jacks, and 41,400 to 55,000 kPa (6000 to 8000 psi) for axle jacks at
37、 rated capacity. 6.1.4 Overload Protection: The hydraulic system shall have overload protection. 6.1.5 Air Entrapment: The hydraulic system shall be provided with provisions to purge it of entrapped air. 6.1.6 Auxiliary Pumps: When specified the hydraulic system shall include provisions to enable op
38、eration either from a pneumatic pressure operated pump, electric power operated pump, external hydraulic pressure source, and/or when connected to a manifold, enable operation in conjunction with other jacks. FIGURE 1 - Typical Hydraulic System, Hydraulic Aircraft Jack 6.2 Components: 6.2.1 Pump: 6.
39、2.1.1 Description: The pump shall be a piston type and operated by hand. When specified, the jack shall include a pneumatic or electric driven pump that is independent from the hand operated pump. Pneumatic operated pumps shall include a provision to limit pressure to 105% to 110% of the pressure re
40、quired to lift the rated capacity of the jack. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AS4775 Revision A - 10 - 6.2.1.2 Handle: The ratio between the jack ram and pump piston shall be suc
41、h that a force of not greater than 445 N (100 lbf) is required at the end of the pump handle to raise a load equivalent to the rated capacity of the jack. The pump handle shall be removable from the pump, and provisions should be made to stow it on the jack. 6.2.1.3 Filtration: The pump should be eq
42、uipped with an inlet screen of approximately 50 mesh. 6.2.1.4 Surface Finish: The pump piston shall be polished to a 16 RMS finish. 6.2.1.5 Plating: The pump piston shall be hard chrome plated. 6.2.1.6 Seals: Pump piston seals shall be of the O-ring type with backup rings or lip seals. 6.2.2 Reservo
43、ir: 6.2.2.1 Capacity: The hydraulic fluid reservoir shall have a capacity equal to the amount of fluid required to fully extend the jack plus a 10% minimum reserve. For reservoirs exceeding 2 U.S. Gallons, a level indicator should be included. 6.2.2.2 Access: A filler plug shall be provided on the t
44、op of the reservoir. The reservoir should include a clean-out cover or method of disassembly for cleaning. 6.2.2.3 Markings: The reservoir shall be clearly marked with the type of fluid to be used. 6.2.2.4 Air Vent: The reservoir air valve or vent shall be located on or near the top of the fluid res
45、ervoir. It shall be sized to accommodate the maximum amount of air being displaced by fluid. When specified for jack transport with fluid, the reservoir shall include provisions for closing the air vent to prevent fluid loss from tipping. A permanent placard or automatic device shall be included to
46、open the vent for jack operation. 6.2.3 Jack Rams and Cylinders: 6.2.3.1 Covers: Jacks with external threaded rams should be provided with a removable cover to prevent the entrance of rain and dust when in transport, storage, or not in use. 6.2.3.2 Surface Finish: The sealing and bearing surface of
47、the ram and ram cylinder shall be polished to a 16 RMS finish. 6.2.3.3 Plating: The internal surfaces of the ram cylinders shall be hard chrome plated. Axle jack ram cylinders may be induction nitrided. Rams shall be hard chrome plated or induction nitrided, except for threaded rams, which shall be
48、cadmium, electroless nickel, or zinc plated. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AS4775 Revision A - 11 - 6.2.3.4 Bearings: The ram and cylinder bearings used in the jack shall be of
49、sufficient size and contact area to provide maximum stability under all load conditions. The bearings shall be protected as much as possible from abrasive particles encountered during use. 6.2.3.5 Seals: Jack ram seals shall be of the O-ring type with back-up rings or lip type seals. 6.2.3.6 Ram Screw Extension: If the jack is equipped with a ram screw extension, it shall be cadmium, electro
