1、AEROSPACERECOMMENDED PRACTICEARP6265Issued 2014-12Tire Burst Test MethodologyRATIONALEThis SAE Aerospace Recommended Practice provides a standard method for testing tires to determine their burst characteristics. This test does not replace the FAA hydrostatic test to test the strength of the tire, n
2、or does it replace the need to comply with 14CFR Part 25.729(f) and CS 25.734, and the associated AMC, including Type Burst Pressure Effect model.INTRODUCTION The standard test methodology presented in this ARP is based on two of the more prevalent types of tire damage that lead to a tire burst: (1)
3、 partial skid-through of the tread and casing and (2) FOD (Foreign Object Debris) perforation of the casing. The test method presented in this ARP is based on actual test experience. It should be noted that tire under inflation is the biggest contributor to tire bursts on the ground. However, listin
4、g or cataloging all the tire failure modes is not the intent of this ARP, rather the purpose of this ARP is to develop a test to characterize the response of a tire when bursting.TABLE OF CONTENTS 1. SCOPE 31.1 Purpose. 32. REFERENCES 32.1 Applicable Documents 32.2 DEFINITIONS . 43. TEST PARAMETERS
5、. 53.1 Burst Pressure 53.2 Test Article 53.3 Test Temperature 54. SIMULATED TIRE DAMAGE 54.1 Partial Skid-Through (Brake Lock-up Skid Damage) 54.2 FOD Cut 65. MEASUREMENTS AND PHOTOGRAPHY 66. TEST PROCEDURE. 66.1 Trial and Error Method 76.2 Hot Wire or Hot Disk Method 7_SAE Technical Standards Board
6、 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 therefrom, is the sole responsibilit
7、y of the user.”SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions.Copyright 2014 SAE InternationalAll rights reserved. No part of this publication may be reproduced, stor
8、ed 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: +1 724-776-4970 (outside USA)Fax: 724-776-0790Emai
9、l: CustomerServicesae.orgSAE WEB ADDRESS: http:/www.sae.orgSAE values your input. To provide feedbackon this Technical Report, please visithttp:/www.sae.org/technical/standards/ARP6265 SAE INTERNATIONAL ARP6265 Page 2 of 157. DATA REDUCTION 7 7.1 Final Report. 8 8. NOTES 8 Figure 1 Tire Buffed to Si
10、mulate Partial Skid-Through with Hot Wire. 9Figure 2 FOD Damage 20% of Tire Width (shown without hot wire) 10Figure 3 Tire Prepared to Simulate FOD Damage - With Hot Wire 11Figure 4 Example Shown with Hot Disk 12Figure 5A Pressure Transducer Array. 13Figure 5B Fixture for Pressure Transducer Array 1
11、4Figure 6 Alternate Pressure Transducer Array . 15SAE INTERNATIONAL ARP6265 Page 3 of 151. SCOPE This document describes a recommended test procedure to assess the burst characteristics of tires used on 14CFR Part 25 or similar transport airplanes. 1.1 Purpose Each airframer is required to demonstra
12、te compliance to 14 CFR Part 25.729(f) (FAA) and CS 25.734 and 25.1309 (EASA) with regard to the performance of the equipment and systems under a failure condition. The AMC 25.734 provides a set of models defining the threats originating from failures of tires and wheels.Should an airframer wish to
13、use a model other than those provided by the AMC, then they would have to gather sufficient evidence and present the data to the certifying authority in order to gain their acceptance of the alternative means of showing compliance.There is no standard tire test methodology by which it can be determi
14、ned how a tire will behave during an actual tire burst event. Standardization of the test and measurement method is beneficial since it allows the tire suppliers, airframers, and certifying authorities to consistently characterize the response of each candidate tire. This ARP presents such a standar
15、dized test.It should be noted that this test method does not provide a characterization of every failure mode a tire can experience. It cannot be used to model a failure leading to a flailing tread, or a tread disbond failure, for instance. It is for this reason that it is important to involve the c
16、ertifying authority at an early stage, in order to agree the extent to which the results of the test can be used in the showing of compliance.This test has been proposed for the current tire technologies (bias and radial), however, should a new tire design be proposed, then the validity of this test
17、 method for fully capturing the failure modes of the new design would need to be re-evaluated.2. REFERENCES2.1 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
18、publications 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 spec
19、ific exemption has been obtained.2.1.1 SAE PublicationsAvailable 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. Lay, M., Macy, W., and Baxter, A., “An Investigation of Aircraft Tire Blow
20、outs,“ SAE Technical Paper 961312, 1996, doi:10.4271/961312.(This paper was written as a result of work performed at the WPAFB Landing Gear Test Facility (LGTF) in which a skid patch was buffed into a sample tire and measured the burst pressure wave that resulted from the release of the inflation pr
21、essure.)SAE INTERNATIONAL ARP6265 Page 4 of 152.1.2 Other PublicationsFARS are available from Federal Aviation Administration, 800 Independence Avenue, SW, Washington, DC 20591, Tel: 866-835-5322, www.faa.gov.14 CFR Part 25.729(f) Retracting Mechanism To obtain JARs (this is IHS): Complete online fo
22、rm, Tel: 800-447-3352 (USA/Canada) or +1-303-397-2295 (Worldwide), FAX: 303-397-2599, TDD: 303-754-4032, E-mail: EASA Certification Standards (CS) are available from European Aviation Safety Agency, Postfach 10 12 53, D-50452 Cologne, Germany, Tel: +49-221-8999-000, www.easa.eu.int.CS 25.734 Protec
23、tion against wheel and tyre failures AMC 25.734 Protection against wheel and tyre failures2.2 Definitions 2.2.1 IN-SERVICE TIRE BURSTA tire burst is the rapid, if not instantaneous, release of a tire/wheel assemblys pressurized gas due to a perforation of thetires casing. 2.2.2 TIRE RESPONSE TO AN I
24、N-SERVICE BURST A tire can burst while rolling on the ground (landing gear extended), or less frequently, in the wheel well. In the case of the tire on-ground with the gear extended, damage can result from the high-pressure gas plume impinging on the surrounding equipment installations, or the flail
25、ing tire structure (loose tread that is spinning) striking surrounding equipment or in some cases separating from the tire as thrown tread (treadshed). In-flight tire bursts are related to previous damage to the tire, while rolling on-ground. Upon the tires burst, the damage to the surrounding struc
26、ture and systems is considered to be caused by radially displaced sections of the tire (no debris separation due to tire spinning) and from the pressure effect ofthe resulting nitrogen jet.2.2.3 TEST GOALS AND OBJECTIVESThe primary reason for performing the tire burst tests is to determine how the t
27、ire fails, the size of the burst opening, the physical distortions, extensions, and orientations of the casing, and the size and direction of any released debris or “flap”(i.e., a displaced section of tire material). This characterization should be made on a number of sample tires which represent a
28、class or family of tire design or architecture. Some questions that should be kept in mind: Does the radial open into a 30 degree wedge shape which is the basis for the EASA radial tire burst model? Does the burst produce flap(s) that can strike equipment in the wheel well when the landing gear is f
29、ully retracted or on the ground with the gear extended. The desired outcome would be no flap(s). If flap(s) are present, the tire manufacture and the airframer will need to decide if the tire needs to be redesigned such that there are noflaps.If the intent is to use the results of this test to justi
30、fy an alternative means of compliance to the models described in AMC 25.734, then it is recommended that this intention and the test proposal be discussed with the certifying authority before any effort is expended in the planning and preparation of the test.SAE INTERNATIONAL ARP6265 Page 5 of 15Pre
31、ssure data may also be collected to validate a computational fluid dynamic (CFD) analysis that an airframer may wish to use as an alternate means of compliance.NOTE: A test where the pressure slowly decays (not instantaneously), a “fizzle,” is not considered a successful test and must be rerun. The
32、tire must burst.3. TEST PARAMETERS3.1 Burst Pressure A typical tire bursts as the result of damage to the tire. The damage can be a partial skid-through (tree rings) or a cut from FOD (Foreign Object Debris) damage. In the wheel well the tire is pressurized, unloaded and not spinning. For a tire to
33、burst in the wheel well, the tires structural strength to resist the force of the contained inflation pressure must be overcome by the contained inflation pressure. The condition after take-off which typically brings about the tire burst is the heating of the contained gas. For landing gear with bra
34、ked wheels, heat transfer into the contained gas of the tire/wheel assembly can cause the pressure of the contained gas to increase, increasing the pressure beyond the remaining strength of a damaged tire casing. The increase in tire pressure is the result of heat soak back from the brake. The resul
35、ting internal tire gas temperature is less than the fuse plug temperature and the internal tire pressure is lower than the pressure relief valve setting.For a non-braked gear, there is no heat source other than tire flexing that will substantially increase the tire inflation pressure. Once the gear
36、is retracted the tire begins to cool and the gauge pressure of the tire reduces, this differentiates it from a tire on a braked gear.For purposes of characterizing the tires response to burst failure, the pressure level at the point of burst is recommended to be at least 130% of the maximum operatio
37、nal unloaded inflation pressure for the applicable aircraft. The “requestor” (airframer) is responsible for defining the pressure and obtaining the agreement of the certification authorities.3.2 Test ArticleThe burst tests should be conducted on production quality tires. This test would need to be p
38、erformed for each new tire p/n to confirm it was no worse than current p/n.It may be necessary to perform tests on a tire of similar size and construction if a production tire is not yet available for the desired size. The validity of such a test should be coordinated with the certifying authorities
39、 prior to being performed.3.3 Test Temperature It is not necessary to elevate the temperature of the tire since the tire burst pressure as stated in 3.1 is satisfactory to simulate brake heating. Therefore, the temperature of the test tires can be at the ambient conditions of the test facility, arou
40、nd 80 F 20 F. 4. SIMULATED TIRE DAMAGETwo of the more common reasons for a tire to burst in the wheel well are from brake lock-up skid damage (partial skid through) and FOD (Foreign Object Debris) perforations. The test article preparation should be as follows. 4.1 Partial Skid-Through (Brake Lock-u
41、p Skid Damage)The test article should be prepared in such a manner to simulate a partial skid-through. The size and shape of the skid patch should be similar to the (loaded) footprint that is reported in the qualification test report at rated service inflationpressure. Remove the skid patch area eit
42、her by buffing, cutting away tire material or a similar method to produce a skid pattern similar to that shown in Figure 1. Care must be taken to ensure that the test article is prepared in a manner that closely simulates actual in-service skid damage. The depth of the skid damage should be such tha
43、t the calculated tire burst strength is equal to or slightly above the burst pressure level per 3.1.SAE INTERNATIONAL ARP6265 Page 6 of 154.2 FOD CutThe test article should be prepared with a cut that simulates an in-service FOD cut. The most common FOD cut occurs in the crown of the tire. The lengt
44、h of the cut should be 20% of tread width and should be wide enough (1.0 inch) to accommodate the heating element, as shown in Figures 2 and 3. For simplicity and consistency, the cut should run perpendicular to the direction of rotation. The depth of the skid damage should be such that the calculat
45、ed tire burst strength is equal to or slightly above the burst pressure level per 3.1.5. MEASUREMENTS AND PHOTOGRAPHYa. Measurement Location, Sample Rate ConsiderationsBecause the damaging portion of the tire burst event is over in less than 10 ms, high speed cameras and high sampling rate pressure
46、transducers are required. Pressures should be sampled at a rate on the order of 105samples per second. Whether the test goal is to determine the mode of failure or to gather pressure data using a pressure array, the pressure inside the tire should be measured at a location opposite of the burst loca
47、tion to determine the tire pressure bleed down rate. Based on the bleed down rate, the average tire burst surface area can be determined.One of the goals of these tests is to measure the size of the burst opening; any physical distortions, extensions, and orientations of the casing; the size and dir
48、ection of any released debris; and measure any flap(s). As such, post-burst inspections, photographs, and measurements should be taken as well as preparing a written description of the damaged areas.b. PhotographyBurst tests should be photographed from top, side, and end using suitable high-speed ca
49、meras. Still photography of the burst opening, flaps, physical distortion, and any debris should be taken.c. Pressure ArrayAnother goal of the test is to measure the burst plume impact pressure as a function of distance from the burst surface. The jet is symmetrical so measurements can be taken in either an X pattern or a V pattern centered o
