1、BRITISH STANDARD AEROSPACE SERIES BS2M47:1990 (Superseding BSM47) Specification for Retreading of cross ply tyres for aircraft UDC629.027.23:629.012.55.002.58:(083.71).006.3/.8:629.018BS2M47:1990 This BritishStandard, having been prepared under the directionof the Aerospace Standards Policy Committe
2、e, waspublished under the authorityof the Board of BSI andcomes into effect on 29June1990 BSI12-1999 The following BSI references relate to the work on this standard: Committee reference ACE/59 Draft for comment85/73551DC ISBN 0 580 17484 0 Committees responsible for this BritishStandard The prepara
3、tion of this BritishStandard was entrusted by the Aerospace Standards Policy Committee (ACE/-) to Technical Committee ACE/59, upon which the following bodies were represented: British Airways British Rubber Manufacturers Association Civil Aviation Authority (Airworthiness Division) Ministry of Defen
4、ce Retread Manufacturers Association Society of British Aerospace Companies Ltd. Amendments issued since publication Amd. No. Date of issue CommentsBS2M47:1990 BSI 12-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 Retreading 1 4 Retreaded tyre
5、4 5 Type test 4 6 R level proof (establishment) 5 7 Quality assurance 5 8 Marking 6 Appendix A Type test report for a retreaded cross ply aircraft tyre 8 Appendix B R level proof test 9 Figure 1 Typical tyre section 3 Table 1 Ply penetration repair limit 3 Table 2 R level proof 6 Publications referr
6、ed to Inside back coverBS2M47:1990 ii BSI 12-1999 Foreword This BritishStandard has been prepared under the direction of the Aerospace Standards Policy Committee and is a revision of BS M47:1975, which is withdrawn. In this revision account has been taken of modern tyre testing criteria and retread
7、progression requirements have been included. Also included are more specific details on casing repair, acceptance limits and the provision of an alternative retread date marking code. This BritishStandard is based on the minimum qualification, acceptance and marking requirements for retreaded cross
8、ply tyres for use on aircraft operated under the jurisdiction of the UK Civil Aviation Authority. This BritishStandard is generally aligned with European and USA practice. The approving authority referred to in this BritishStandard is the Airworthiness Division of the Civil Aviation Authority. A Bri
9、tish Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a fro
10、nt cover, an inside front cover, pagesi andii, pages1 to10, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS2M47:1990 BSI 12-1999 1 1 Scope T
11、his BritishStandard specifies requirements for the retreading of cross ply aircraft tyres, including carcass rejection criteria and repair limits before processing. It also specifies type approval tests, quality assurance requirements and interchangeability limits to be met by the retreaded tyre aft
12、er processing. Except where otherwise stated, these requirements apply to both tubed and tubeless tyres. NOTE 1The titles of the publications referred to in this standard are listed on the inside back cover. NOTE 2The latest revision of an Aerospace Series standard is indicated by a prefix number. T
13、he latest edition of the standard should be used. 2 Definitions NOTESeeFigure 1. For the purposes of this BritishStandard, the definitions given in BS3558 apply together with the following. 2.1 batch a group of tyres of identical size, type and original manufacture that are retreaded in one producti
14、on run 2.2 buffing the preparation of the tyre surface before the application of new material 2.3 chine (deflector) a specially profiled circumferential water-deflecting rib located on one or both side walls of the tyre at a predetermined distance below the tread edge 2.4 mould tread pattern depth t
15、he nominal depth of the groove nearest the centreline of the mould 2.5 R level the number of times that a carcass has been subjected to a retreading operation (e.g.third retread=R3) 2.6 retreading a process of reconditioning a worn tyre by one of the following methods a) bead-to-bead remoulding. A p
16、rocess in which material is removed as necessary and new material, extending from bead area to bead area, is applied. b) recapping. A process in which material is removed from the worn tread and over the shoulders and new material is applied. c) top-capping. A process in which the worn tread materia
17、l only is renewed. 2.7 speed ratings the maximum ground speed at which a tyre is designed to operate, as follows a) low speed tyre. A tyre designed to operateatmaximum ground speeds up to120miles/h(104kn). b) high speed tyre. A tyre designed to operateatmaximum ground speeds above120miles/h(104kn).
18、2.8 tread reinforcement one or more layers of material fitted within or below the wearable part of the tread 2.9 tyre fitting lines the circular moulded lines on the outside of the upper bead area to indicate concentricity of the tyre and wheel when fitting 2.10 vent holes holes made in the tyre abo
19、ve the wheel rim area for relieving permeating and entrapped air within the carcass and/or between the tube and carcass of a tubed tyre 3 Retreading 3.1 Rejection criteria before processing 3.1.1 A tyre shall not be used for retreading if it displays any of the following features: a) injuries to the
20、 bead or bead area; NOTERepairs may be made if the chafe-resistant material only is damaged or loose, or if damage does not extend into the plies of the tyre and if there is no sign of separation in the bead area. b) bead injuries that affect the seal of the bead on tubeless tyres; c) evidence of se
21、paration exceeding process specification limits between plies or around the bead wire; d) injuries requiring reinforcement and all injuries requiring sectional repair; e) kinked or broken bead wires; f) weather cracking (ozone cracking) or radial cracks that penetrate body plies;BS2M47:1990 2 BSI 12
22、-1999 g) evidence of flex breaks; h) loose, internally damaged or broken cords; i) broken or cut cords in the outside sidewall or shoulder area; j) evidence of blisters or heat damage to the bead seat where reversion, scorching or rubber flaking has occurred; k) cracked, deteriorated or damaged inne
23、r liners that exceed the repair limits; NOTE 1Liner splice damage defects may be repaired if less than250mm in length. NOTE 2Other liner defects if less than50mm in length may be repaired provided that there are no more than10 of them per tyre and no more than three in any quadrant. l) flat spots an
24、d skid burns that have penetrated more than one carcass ply; m) saturation with fuel, grease or oil to the point where tread adhesion or tyre integrity is adversely affected; n) sidewalls that have been buffed and veneered more than three times; o) punctures that penetrate through the cord body. 3.1
25、.2 Defective balance patches shall be removed from all tyres accepted for retreading under3.1.1 and each area of the carcass shall be inspected by non-destructive methods to ensure that it is suitable for retreading. 3.1.3 A tyre that has been run deflated (seenote1) or overloaded (seenote2) shall o
26、nly be used for retreading at the discretion of the retreader after extensive non-destructive testing has shown the carcass to be acceptable. NOTE 1A tyre is considered to have been run deflated if it has been used at less than90% of minimum operating pressure. NOTE 2A tyre is considered to have bee
27、n run overloaded if it is the companion to a deflated tyre on a common axle. 3.2 Preparation for processing 3.2.1 Buffing. The entire surface to be rerubbered shall be buffed, care being taken to avoid gouging or burning or loose rubber ends. The contour of the buffed area shall suit the tread profi
28、le and the tread mould to be used. 3.2.2 Examination of carcass. The carcass shall be examined after buffing to ensure that any injuries do not exceed the limits given in3.3 or3.4 as appropriate. 3.2.3 Repair. Before applying the tread rubber and/or reinforcing plies, any buffing damage and/or carca
29、ss injuries shall be repaired within the limits given in3.3 or3.4 as appropriate. 3.3 Repair limits for tyres operated above120miles/h 3.3.1 Tread area. Cuts, cracks or other tread area injuries that are38mm in length and6mm in width or less on the first cord body ply and that do not penetrate more
30、than40% of the actual tyre cord body plies shall be repaired. Any tread injury repaired by skiving or rasping shall not have the final repair greater than50mm in length. 3.3.2 Tread injuries. Tread injuries shall be repaired if they penetrate a distance equal to40% of actual tyre cord body and if th
31、ey are38mm in length or less on the first cord body, limited to six per tyre and not less than60 apart along the tyre circumference. Maximum repairs shall be identified on the tyre. 3.3.3 Sidewall rubber. Surface defects of any degree, weather cracking (ozone cracking), radial and circumferential cr
32、acks, cuts and snags shall be repaired provided the injuries do not penetrate the cord body fabric plies. 3.3.4 Bead area. Minor injuries to the bead area shall be repaired provided the plies are not damaged. 3.3.5 Bead seal. The bead seal shall not be affected or intersected by impressions or depre
33、ssions. 3.3.6 Bead face and bead heel. The bead face and bead heel areas shall be smooth. 3.3.7 Bead toe. The bead toe shall be trimmed so that no edges are exposed above the bead face and so that any bead toe flash remaining does not protrude more than3mm from the face contour of the bead. If trimm
34、ing of the bead toe is necessary, the trimming shall not cut or expose the tyre cord material or more than one layer of chafer material. 3.3.8 Chafer strip. Minor injuries in the chafer strip and slight tyre tool injuries in the general bead area shall be repaired if they do not extend into the plie
35、s of the tyre and if there is no sign of separation in the bead area. Loose or blistered chafer strips shall be repaired or replaced. 3.3.9 Inner liner. Inner liner surface damage and defects other than liner splices that are less than50mm in length shall be repaired. A maximum of10 of these repairs
36、 shall be acceptable with no more than three repairs in any quadrant. Liner splice damage defects shall be repaired if less than250mm in length. 3.3.10 Exposed cord. Exposed cord, either in the breaker or carcass ply, shall not exceed1% of the buffed total tread area on one spot or more than2% for t
37、he entire tyre. Exposed cord shall not exceed one carcass ply in depth.BS2M47:1990 BSI 12-1999 3 3.4 Repair limits for tyres operated below120miles/h 3.4.1 Bead injuries. Repairs shall be made where only the chafe-resistant material is damaged or loose or where minor injuries do not penetrate more t
38、han25% of the tyre plies, up to a maximum of three damaged plies. 3.4.2 Tread or sidewalls. Injuries shall be repaired by the spot method. This shall include cuts in the tread area that are smaller than12mm in length and do not penetrate more than the number of plies given in Table 1 into the cord b
39、ody. Table 1 Ply penetration repair limit 3.5 Process 3.5.1 Materials. The materials used in the retreading process shall be chemically compatible with the materials used in the original manufacture of the tyre and shall enable the retreaded tyre to comply with clause4. 3.5.2 Reventing. The tyre sha
40、ll be revented if the original vent holes are determined to be no longer operative or if the tyre has been subjected to bead-to-bead remoulding. The depth of venting shall be sufficient to penetrate at least the two outermost plies. 3.5.3 Retreaders specification. The retreading processes (recapping
41、, top-capping or bead-to-bead remoulding) and curing shall be carried out in accordance with the individual retreaders specification. Figure 1 Typical tyre section Number of plies Maximum cut depth 16 0 2plies 4pliesBS2M47:1990 4 BSI 12-1999 4 Retreaded tyre NOTEAll dimensional and functional requir
42、ements of aircraft tyres are given in BS2M45-1. 4.1 Interchangeability A retreaded tyre shall be interchangeable with the equivalent new tyre and shall comply with the following requirements: a) the inflated dimensions, before or after dynamic testing (see5.2.2), shall not exceed the grown dimension
43、s of a new tyre specified in BSM45-1; b) the mass shall not exceed the mass specified by the airline commissioning the retreading; c) the maximum moment of static imbalance shall be as specified in4.2.1; d) the speed and load rating shall not exceed that marked on the tyre sidewall; e) the chine sha
44、ll not be altered from the original profile. 4.2 Balancing 4.2.1 The tyre shall be balanced. The maximum moment of static imbalance of a tyre M shall be less than the value calculated from the empirical equation: M =(3.87 10 5 ) D 2 where D is the maximum outside diameter (in mm). NOTECertain aircra
45、ft applications may require a lower M value, and if they do this should be stated in the contract or order. 4.2.2 Residual out of balance shall be corrected by applying a balance patch to the inside of the tyre in the crown area, or by another approved method. The balance patch shall be such that it
46、 will not chafe the inner tube, if fitted. 4.2.3 Any balance patch or other materials added to the inside of the tyre shall be securely attached to withstand service operation but shall be fixed such that removal before reprocessing shall not damage the inside surface of the tyre. 5 Type test 5.1 Te
47、st requirements 5.1.1 The type tests given in5.2 shall be conducted at each manufacturing plant on the following occasions: a) whenever the manufacture of a new size of retread is undertaken; b) before initial fit of a retread to a different aircraft application of equal load rating to that marked o
48、n the retread. 5.1.2 Type testing shall be conducted on first life(R1) retreaded tyres manufactured from carcasses that have been previously approved by theapproving authority (seeforeword) for each aircraft type to which it is intended to fit the retread. 5.1.3 Carcasses used to manufacture R1 retr
49、eads for type testing shall have been worn to a minimum of80% in service, and shall have representative maximum damage repairs (see3.3 or3.4) naturally or artificially induced. NOTE 1Initially, the retreader should successfully type test a retread carried out on a worn first life carcass approved by the approving authority and produced by a specific new tyre manufacturing plant. Approval may then be given for retreads of the same designation and for the same aircraft type produced from approved carcasses from other new tyre manufacturing plants provided that it c
