1、BRITISH STANDARD BS 4A 100:2003 Aerospace series Specification for general requirements for bolts and free running nuts of tensile strength not exceeding 1 249 MPa ICS 49.030.20; 49.030.30 Incorporating Amendment No. 1 and Corrigendum No. 1BS 4A 100:2003 This British Standard was published under the
2、 authority of the Standards Policy and Strategy Committee on 13 November 2003 First edition April 1993 Second edition October 2000 The following BSI references relate to the work on this British Standard: Committee reference ACE/12 Draft for comment 89/79827 DC Committees responsible for this Britis
3、h Standard The preparation of this British Standard was entrusted by the Aerospace Standards Policy Committee (ACE/-) to Technical Committee ACE/12, upon which the following bodies were represented: The Association of Electronics, Telecommunications and Business Equipment Industries British Industri
4、al Fasteners Federation Ministry of Defence Society of British Aerospace Companies Ltd. ISBN 978 0 580 63694 3 BSI 2008 Amd. No. Date Comments 17434 28 September 2007 See foreword C1 31 July 2008 Revision of 10.5.2.1 Amendments/corrigenda issued since publicationBS 4A 100:2003 i Contents Page Commit
5、tees responsible Inside front cover Foreword ii 1S c o p e 1 2M a t e r i a l 1 3 Manufacture 1 4D i m e n s i o n s 1 5 Runout and lead threads for rolled threads 1 6 Screw thread form and class of fit 1 7 Anti-corrosion treatment 2 8 Identification marking 2 9 Quality assurance procedure 3 10 Addi
6、tional requirements for cold-forged and hot-forged bolts 9 Appendix A Dimensions of unified thread identification features on aircraft bolts and nuts 14 Figure 1 Geometrical tolerances for bolts 6 Figure 2 Geometrical tolerances for nuts 7 Figure 3 Nut squareness gauge 8 Figure 4 Minimum acceptable
7、standard of grain flow (after machining if applicable) 12 Figure 5 Ordinary bolt 14 Figure 6 Bolts with close tolerance shanks 15 Figure 7 Hexagonal-headed shear bolts 16 Figure 8 Mushroom head bolts with recess 16 Figure 9 Pan head bolts with recess 17 Figure 10 Nut 17 Table 1 Inspection levels 4 T
8、able 2 Surface texture 4 Table 3 Geometrical straightness tolerances for bolt shanks 7 Table 4 Nut sequences tolerances 8 Table 5 Maximum depth of defect 9 Table 6 Bolt hardness ranges 11 Table 7 Minimum breaking loads 13 Table 8 Alternative identification features for hexagonal-headed bolts other t
9、han shear bolts 18 Table 9 Alternative identification features for hexagonal-headed shear bolts 19 Table 10 Identification features for mushroom head and pan head bolts 19 Table 11 Identification feature for nuts 20 BSI 2008BS 4A 100:2003 ii Foreword This new edition of BS 3A 100 incorporates techni
10、cal changes only (a new Clause 10). It does not reflect a full review, or revision, of the standard which will be undertaken in due course. This British Standard, prepared under the direction of the Aerospace Standards Policy Committee, it is intended primarily to improve the manufacture of aerospac
11、e bolts and free running nuts and the quality of their inspection. It also brings these requirements up to date in relation to current specifications for aerospace fasteners either published or in the course of publication. It constitutes a new edition of BS 3A 100:1991. This new edition does not af
12、fect the interchangeability of items manufactured to their own individual or nut standard, and fasteners manufactured in compliance with BS 2A 100:1968, may continue to be furnished until stocks are exhausted. This British Standard is intended for use in conjunction with those “A” series British Sta
13、ndards in which compliance with this standard is a specific requirement. It may also be applicable to other aerospace bolts and nuts if required by the contract, drawing or order. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its c
14、orrect application. Summary of pages This document comprises a front cover, an inside front cover, pages i to ii, pages 1 to 20, an inside back cover and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Compliance with a British Standard
15、cannot confer immunity from legal obligations. The start and finish of text introduced or altered by Amendment No. 1 is indicated in the text by tags !“. BSI 2008BS 4A 100:2003 1 1 Scope This British Standard specifies the general requirements for aerospace bolts and free running nuts of tensile str
16、ength not exceeding 1 249 MPa. 2 Material The bolts and nuts shall be manufactured from the material specified in the relevant bolt or nut standard. NOTE Bolts or nuts may be rejected at any time for faults in or revealed by manufacture although they have been made from material passed previously. 3
17、 Manufacture 3.1 Bolts Bolts shall be manufactured by machining from bar, by cold-forging or hot-forging. 3.2 Cold-forged or hot-forged steel bolts Cold-forged or hot-forged steel bolts shall be manufactured by a process to fulfil the requirements in Clause 10. 3.3 Screw threads 3.3.1 All unified cl
18、ass 3A threads that comply with BS 1580 and all threads that comply with ISO3161 shallbe rolled in the finally heat treated condition 3.3.2 Unless otherwise specified by the bolt standard all other threads shall be cut or rolled at the option of the bolt manufacturer, however the lead end chamfer of
19、 bolts in nominal size and under may deviate from that indicated on the bolt standard or drawing, due to metal extrusion on thread rolling, subject to the following requirements being met. a) The minor diameter of the lead thread shall be continuous. b) The lead end face shall be square to the axis
20、of the thread within the tolerance permitted by the following test. The bolt shall be screwed into a ring gauge the face of which is square to the axis of the thread, until the low point of the lead end is flush with the gauge face. The protrusion shall not exceed one pitch or 0.030 in, whichever is
21、 the smaller. 4 Dimensions All bolts and nuts shall comply with the dimensions and tolerances specified in the relevant standard. 5 Runout and lead threads for rolled threads Rolled threads shall have runout and lead threads complying with BS A 231. 6 Screw thread form and class of fit 6.1 When Brit
22、ish Association (BA) threads are specified for bolts they shall comply with the close class limits and fits specified in BS 93 1) . In view of the tendency for closely fitting bolts and nuts in corrosion resisting steel to seize when tightened together, the major, effective and minor diameters of un
23、plated corrosion resisting steel bolts shall be 0.001 in smaller than the maximum limits for close class bolts specified in BS 93 1) . NOTE In order to avoid any undue restriction of the tolerance allowed for screwing, the major, effective and minor diameters may be 0.001 in smaller than the minimum
24、 limits for close class bolts specified in BS 93 1) . 6.2 When BA threads are specified for nuts they shall comply with the limits and fits specified in BS 93 1) . 1) Obsolescent. 3 8 - ! “ BSI 2008BS 4A 100:2003 2 6.3 When British Standard Fine (BSF) threads are specified for bolts they shall compl
25、y with the medium class limits and fits specified in BS 84 2) . In view of the tendency for closely fitting bolts and nuts in corrosion resisting steel to seize when tightened together, the major, effective and minor diameters of unplated corrosion resisting steel bolts in BSF and larger shall be 0.
26、002 in smaller than the maximum limits for medium class bolts specified in BS 84 2) . NOTE In order to avoid any undue restriction of the tolerance allowed for screwing, the major, effective and minor diameters of in BSF and larger may be 0.002 in smaller than the minimum limits for medium class bol
27、ts specified in BS 84 2) . 6.4 When BSF threads are specified for nuts they shall comply with the normal class limits and fits specified in BS 84 2) . 6.5 Unless otherwise specified in the product standard unified threads for bolts shall comply with the class 2A limits and fits specified in BS 1580
28、or BS A 346 as applicable. 6.6 Unless otherwise specified in the product standard unified threads for nuts shall comply with the class 2B limits and fits specified in BS 1580 or BS A 346 as applicable. 7 Anti-corrosion treatment 7.1 Anti-corrosion treatments specified for the bolts or nuts in the re
29、levant standard shall, unless otherwise specified, comply with the requirements of the latest issue of the following appropriate process specification: anodizing: Defence Standard 03-24 (chromic process); cadmium plating: Defence Standard 03-19. 7.2 Colour identification on anodised fasteners Due to
30、 the difficulties of uniformly colourising the anodic coating, it shall be acceptable for up to 10 % of each batch supplied to exhibit variations in colour, which shall not be the cause for rejection. 8 Identification marking 8.1 Hexagonal-headed bolts 8.1.1 Unless otherwise stated on the product st
31、andard, fasteners shall be identified as stated in 8.1.2, 8.1.3, 8.1.4 and 8.1.5. 8.1.2 Bolts of 2 BA and No. 10 nominal size and larger shall have the complete part number (e.g. A 102 3D) applied to the upper face of the head. 8.1.3 Bolts with unified threads shall have the appropriate identificati
32、on applied as indicated in Appendix A of this standard. 8.1.4 Each individual package of bolts shall have the complete part number and batch identification number or code clearly shown on each label. 8.1.5 Bolts shall have the manufacturers identification applied to the upper face of the head. 8.2 B
33、olts with other than hexagon heads 8.2.1 Unless otherwise stated on the product standard, fasteners shall be identified as stated in 8.2.2, 8.2.3 and 8.2.4. 8.2.2 Pan head and mushroom head bolts with unified threads shall have the appropriate identification applied as indicated in Appendix A of thi
34、s standard. 8.2.3 Pan, mushroom and countersunk head bolts of 2 BA and No. 10 nominal size and larger shall have the length identification only as given in the appropriate bolt standard marked on the head, unless otherwise stated in the individual product standard. 8.2.4 Each individual package of b
35、olts shall have the complete part number and batch identification number or code clearly shown on each label. 2) Obsolescent. 7 8 - - 7 8 - BSI 2008BS 4A 100:2003 3 8.3 Hexagon nuts 8.3.1 Unless otherwise stated on the product standard, fasteners shall be identified as stated in 8.3.2, 8.3.3, 8.3.4
36、and 8.3.5. 8.3.2 Nuts of in nominal diameter and larger shall have the number of the relevant British Standard (e.g. A 103) applied on one or more of the hexagonal surfaces. 8.3.3 Nuts of 2 BA and No. 10 nominal size and larger with left hand threads shall have the letter “L” applied to one of the h
37、exagon surfaces. 8.3.4 Nuts with unified threads of No. 8 nominal size and larger shall be marked with the identification as indicated in Appendix A of this standard. 8.3.5 Each individual package of nuts shall have the complete part number and batch identification number or code clearly shown on ea
38、ch label. 8.4 Method of marking The method of marking shall be at the option of the manufacturer when in accordance with one of the following. All marking shall be applied to the fasteners in the uncoated condition. 8.4.1 Marking shall be applied by use of controlled pressure die stamping using a Ch
39、aracter marking die of a rounded tip form not less than 0.025 inch height. The depth of impression shall be kept to a minimum consistent with legibility and not more than 0.010 inch depth. 8.4.2 Marking shall be integrally forged with a Character that is not less than 0.025 inch height. 8.4.3 Markin
40、g shall be by microprocessor “controlled dot peen” with a spherical indenting stylus of 0.005 inch an indentation depth of 0.001 to 0.002 inch for steel with a hardness less than 54 Rockwell “C” and indentation depth of not more than 0.003 inch for aluminium. 9 Quality assurance procedure 9.1 Genera
41、l 9.1.1 Quality Assurance Authority The quality assurance system selected shall satisfy the requirements of the quality assurance authority. NOTE 1 The appropriate quality assurance system for the manufacture of aerospace products is ISO 9000:2000 with AS/EN 9100. NOTE 2 Manufacturers and users are
42、advised that in respect of CAA certification, this is no longer appropriate for the manufacturer of standard parts (fasteners). Manufacturers and users should therefore check with their local CAA office for eligibility. 9.1.2 Responsibility for inspection and tests The manufacturer shall be responsi
43、ble for the performance of all inspection and test requirements specified herein. Each manufacturer shall use their own or, exceptionally, any other facilities approved in accordance to Notes 1 and 2 of 9.1.1 for the implementation of these quality assurance and test requirements. 7 16 - BSI 2008BS
44、4A 100:2003 4 9.2 Acceptance of production batches 9.2.1 Definition of batch A batch shall consist of finished bolts or nuts which are of the same type and diameter, fabricated by the same process from material of the same cast, heat treated as one lot and plated as one lot and produced as one conti
45、nuous run, free from any interruptions or changes. 9.2.2 Sampling Random samples shall be taken from each batch in accordance with 9.2.3 for dimensional and non-destructive inspection, and in accordance with 10.1 for destructive testing. 9.2.3 Samples for dimensional and non-destructive inspection S
46、amples for dimensional and non-destructive inspection shall be taken from each batch in accordance with BS 6001 at the levels given in Table 1. The acceptance or rejection shall depend upon the acceptable quality levels (AQLs) applied to the characteristics as given in Table 1. 9.3 Surface texture S
47、urface texture shall be as specified in Table 2 and shall be determined visually except in cases of dispute when measurements shall be made in accordance with BS 1134. Table 1 Inspection levels Table 2 Surface texture AQL Inspection level II Inspection level S-I 0.065 Magnetic flaw detection after p
48、lating 1.0 Thread size Thread run-out Shank diameter (where tolerance is 0.001 in or less) Underhead radius Squareness Driving geometry 2.5 Surface texture (visual) Plain shank length Burrs and plating (visual) Straightness of shank (except when ground) Identifications (visual) Concentricity 4.0 Nut
49、 thickness Head height Overall length Shank diameter (where tolerance exceeds 0.001 in) Point chamfer (visual) Other dimensional characteristics Features Surface roughness to BS 1134 R emax 4m( 4in) Bolts Shank, head bearing face and fillet radius Close tolerance shank 0.8 (32) Other than close tolerance shank 1.6 (63) Thread flank and root radius Rolled thread 0.8 (32) Cut thread 1.6 (63) Other surfaces 3.2 (125) Nuts Bearing faces 3.2 (125) (circular l
