BS-SP-141-1970.pdf

BRITISH STANDARD AEROSPACE SERIES CONFIRMED APRIL 1998 BS SP 141:1970 Specification for Design and performance requirements for toggle type panel fasteners UDC 629.7:621.828.2 Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 03:21:50 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS SP 141:1970 This British Standard, having been approved by the Aerospace Industry Standards Committee, was published under the authority of the Executive Board of the Institution on 31 March 1970 © BSI 02-2000 The following BSI reference relates to the work on this standard: Committee reference ACE/14 Draft for comment 69/1719 ISBN 0 580 05867 0 Foreword This British Standard has been prepared at the request of the Society of British Aerospace Companies Limited. It specifies the requirements for design and performance of toggle type panel fasteners for aircraft. NOTEInformation concerning SI units is given in BS 350, “Conversion factors and tables”, Part 2, “Detailed conversion tables”, Supplement No. 1, “Additional tables for SI conversions”, and PD 5686, “The use of SI units”. This standard makes reference to the following British Standards: BS 410, Test sieves. BS 2011, Methods of environmental testing of electronic components and electronic equipment. Part 2K. Salt mist. BS SP 20, Panel type air filter elements for use with internal combustion engines and compressors on aircraft. A British 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 front cover, an inside front cover, pages i and ii, pages 1 to 7 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. Amendments issued since publication Amd. No.DateComments Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 03:21:50 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS SP 141:1970 © BSI 02-2000i Contents Page ForewordInside front cover 1General1 1.1Scope1 1.2Definition1 1.3Materials1 1.4Protective treatment1 2Design requirements1 2.1General1 2.2Interchangeability1 2.3Operation1 2.4Flush fitting1 2.5Capacity1 2.6Adjustment2 2.7Fitting tolerances2 2.8Shear type fasteners2 3Type tests2 3.1General2 3.2Tensile proof tests2 3.3Torsion proof tests3 3.4Tensile ultimate loads3 3.5Adjustment tests3 3.6Endurance test3 3.7Depth tolerance test3 3.8Malalignment test3 3.9Fluctuating load test3 3.10Operating test4 3.11Resistance to corrosion4 3.12Shear type fasteners4 Appendix A Test schedule6 Appendix B Dust and sand test6 Figure 1 Measuring device for dust and sand tests7 Table 1 Ultimate tensile loads5 Table 2 Maximum operating loads5 Table 3 Minimum range of adjustment5 Table 4 Ultimate shear loads5 Table 5 Test schedule6 Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 03:21:50 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii blank Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 03:21:50 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS SP 141:1970 © BSI 02-20001 1 General 1.1 Scope This British Standard specifies the design and performance requirements for aircraft toggle type panel fasteners. 1.2 Definition For the purposes of this British Standard a toggle type panel fastener is a fastener which secures a panel or panels by the operation of a lever which moves a second lever over a dead centre to provide a geometric lock when in the closed position. 1.3 Materials All materials shall be to specifications agreed to by the Design Approving Authority1). 1.4 Protective treatment Protective treatment shall meet the requirements of the Design Approving Authority (e.g. SBAC Publication RS. 116). 2 Design requirements 2.1 General 2.1.1 Classification. For the purposes of this standard, toggle type panel fasteners shall be classified as Types A, B, C or D and “large” or “small” according to the performances specified in the relevant tables and qualified in accordance with 3.1.1. 2.1.2 Installation. Fasteners shall be capable of being installed without the use of special tools. 2.1.3 Loose parts. The design shall be such that, after assembly of a fastener in the position for which it is intended, there shall be no loose parts when the fastener is unlocked. 2.1.4 Resistance to foreign bodies. Fasteners shall be so designed that operation of their moving parts shall not be impeded by the presence of grit, or other foreign matter, including driven sand or snow. Fasteners shall at all times be capable of satisfactory operation without the application of a lubricant. 2.2 Interchangeability 2.2.1 Each fastener shall be directly interchangeable with any other fastener manufactured to the same specification or part number. 2.2.2 Where fasteners are supplied in two or more portions, each portion shall be fully interchangeable with its counterpart from any other fastener of the same type. 2.3 Operation 2.3.1 Opening and closing, including locking, shall be possible with an arctic-gloved hand, and without the use of special tools. 2.3.2 Each fastener shall be so designed that a positive lock restrains the operating lever from accidental operation, and from operation under all possible conditions of loading, including torsion. Where a large tab pressure area is provided on the lock, this shall be additionally restrained against movement due to negative air pressures. It shall not be possible to engage the lock, without the toggle mating members being properly engaged and closed. It must be immediately visually obvious that a fastener is in the unlocked condition. 2.3.3 Each type and size of fastener shall be operable over a temperature range of from 40 °C to + 70 °C, and shall maintain efficient locking over a range of from 75 °C to + 150 °C, with the exception of Type D which shall maintain efficient locking up to + 275 °C. 2.4 Flush fitting When in the closed position, fasteners shall be flush with the outer surface of the panel. Gaps between the levers and the recess in the panel are to be kept to a minimum consistent with efficient operation. As far as is possible each fastener should be adaptable to a range of panel surface curvatures. 2.5 Capacity 2.5.1 Sizes. In general two sizes of fasteners, hereinafter classified as “large” size and “small” size, are required for Types A and B and these shall be capable of developing the ultimate loads specified in Table 1. 2.5.2 Operating loads. The mean force required to open or close a correctly aligned fastener, when applied at the outer end of the operating lever, and measured in increments of 5° of arc, shall not exceed the amounts specified in Table 2, when loaded with 15 % of the relevant load given in Table 1. 1) In the United Kingdom the Design Approving Authority for fasteners is the Society of British Aerospace Companies Limited (SBAC) 19, King Street, St. Jamess, London, S.W.1. Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 03:21:50 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS SP 141:1970 2 © BSI 02-2000 2.6 Adjustment 2.6.1 Simple but adequate means shall be provided for the initial adjustment of tension, and for wear during the use of the fastener. Such adjustment shall be possible after installation, and shall not require other than the normal range of hand tools. Means shall be provided whereby the setting can be locked at the correct adjustment, and a visible indication given that adjustment has not exceeded the safety limit. 2.6.2 The minimum range of adjustment shall be as specified in Table 3. 2.6.3 Adjustment should be infinitely variable, but if made in definite steps, each step should be as small an increment as is possible. 2.7 Fitting tolerances 2.7.1 Malalignment. Fasteners shall operate efficiently when the two mating parts are displaced relative to each other, from the centre line of a fastener by a distance of not greater than 1.5 mm (large size) and 0.75 mm (small size). 2.7.2 Depth. Fasteners shall operate efficiently when the two mating parts are displaced relative to each other, in a direction normal to the panel surface, by a distance of not more than 1.5 mm (large size) and 0.75 mm (small size) for Type A fasteners and 0.75 mm for Type B (large and small). 2.8 Shear type fasteners 2.8.1 General. In general, shear type fasteners shall conform to all of the preceding requirements with the exception of those in 2.7.1 and 2.7.2 which are inapplicable to fasteners of this type. 2.8.2 Fitting tolerances. The fitting tolerances will depend upon the design of the fastener and should be close enough to develop the required shear load without preventing freedom of operation. 2.8.3 Capacity. Each fastener shall be capable of developing an ultimate shear load, either in the plane of the panel or normal to it as specified in Table 4. 3 Type tests 3.1 General 3.1.1 All samples shall undergo the appropriate tests detailed below, as scheduled in Appendix A to the satisfaction of the Inspecting Authority2). 3.1.2 Test reports countersigned by the Inspecting Authority witnessing the tests shall be forwarded together with the drawings to the Design Approving Authority. 3.1.3 The manufacturer shall disclose to the purchaser and Design Approving Authority any proposal to introduce constructions or processes differing from those used for the fasteners submitted to the type tests, and shall obtain the Design Approving Authorities written agreement before applying the change to production. 3.1.4 The tests specified in this standard are to be made on single fasteners, mounted on suitable rigs. In each case the number of fasteners to be tested, and the tests to which individual fasteners are to be subjected, shall be in accordance with Appendix A. 3.1.5 The provision of suitable test rigs and associated equipment is the responsibility of the fastener manufacturer, and shall be to the satisfaction of the Inspecting Authority. 3.1.6 Unless otherwise stated all tests shall be conducted at normal room temperature (15 °C to 20 °C). 3.1.7 The sample fasteners shall be numbered as given in Appendix A for the purposes of recording and allocation of tests. 3.1.8 A fastener shall be deemed not to comply with this standard if it fails any relevant test, or when at the completion of the tests one or more of its components: 1) exhibit undue wear or corrosion; 2) fracture or break; 3) have distorted or take up a permanent set, a) presenting the fastener from being locked or unlocked, or b) allowing the fastener to be unlocked with the application of 75 % or less of the absolute minimum torque; 4) show evidence of grain growth. 3.2 Tensile proof tests 3.2.1 For the purpose of the tensile load tests, suitable test plates, in each of which are incorporated the fixed anchorage and lower socket, for the appropriate size and type of fastener shall be provided. The test plates shall have extensions for fitting in the testing machine. The test plates shall be sufficiently robust to withstand use during the ultimate load tests. 2) The Inspecting Authorities for fasteners in British civil or military aircraft are the Air Registration Board (through a Design Approving Authority approved by the Board) and the Ministry of Technology respectively. Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 03:21:50 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS SP 141:1970 © BSI 02-20003 3.2.2 A direct steady load, equal to 75 % of the ultimate load specified in 2.5.1, shall be applied in the appropriate direction for a period of 5 minutes. During and subsequent to that period, there shall be no visible sign of separation or distortion of any part of the test specimens, or of the bolts or rivets securing the specimens to the test appliance. Three samples of each size and type shall be tested in this manner. 3.3 Torsion proof tests Specimens shall be submitted to a torsion load equal to 25 % of the ultimate tensile load specified in 2.5.1. The torsion load shall be applied in both directions, slowly over a period of 5 cycles. No distortion of the test samples or of their mounting attachments shall be visible. 3.4 Tensile ultimate loads Continuing the test specified in 3.2.2 one of the specimens shall be further tested under a direct steady load, which shall be gradually increased until failure occurs. The failing load shall be not less than the minimum specified in 2.5.1. In the event of doubt arising as a result of this test a further specimen shall be so tested. 3.5 Adjustment tests Efficiency of locking and of the adjustment which governs the tension on the fastener is to be tested as specified in 3.5.1 to 3.5.3. 3.5.1 Types A, C and D fasteners. Each of three new samples shall be tested separately for adjustment. The fastener under test shall be adjusted until the load required to close the fastener is between 44.5 N and 67 N (large size) or between 26.5 N and 40 N (small size). When the fastener adjustment is by finite steps the fastener shall be opened, the adjustment varied by one step, and the fastener again closed. The resulting operating load shall not exceed the values given in 2.5.2. 3.5.2 Type B fasteners. Each of three new samples shall be tested separately for adjustment. The fastener under test shall be adjusted so that the load required to close it is between 22 N and 44.5 N (large size) and between 9 N and 18 N (small size). When the fastener adjustment is by finite steps the fastener shall be opened, the adjustment varied by one step and again closed. The resulting operating load shall not exceed the values given in 2.5.2. 3.5.3 Locking. Every possible attempt is to be made to engage the lock with the mating parts of the panels in various degrees of disengagement. It shall not be possible to close the lock except in the correct fully closed position of the panel. 3.6 Endurance test Three samples of each size and type are to be submitted to a locking/unlocking cycle test at 15 % of the relevant loads given in Table 1, performed at a rate not exceeding 50 cycles per minute, and shall withstand 2 000 complete cycles. Upon satisfactory conclusion of this test, one sample of each type shall be submitted to the torsion and ultimate tensile tests specified in 3.3 and 3.4, the requirements of which shall also be met. 3.7 Depth tolerance test One sample of each size and type shall be mounted in a suitable rig in which metal spacer strips of 1.25 mm or 0.56 mm (large and small size) are inserted to represent a corresponding difference between the planes of the panel surfaces. With the fasteners so arranged, no difficulty shall be experienced in locking or unlocking operations. The rig used for this t