GB/T 42252-2022Test method for torque and preload of aviation threaded collars (English PDF)
航空用高锁螺母力矩及预紧力测试方法
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Issued by
SAMR; SAC
Level / Type
National · Recommended
Issue date
December 30, 2022
Implementation date
April 1, 2023
Scope
GB/T 42252-2022 is the English-translated version of 航空用高锁螺母力矩及预紧力测试方法.
GB/T 42252-2022 is the Chinese national test method for the torque and the pre-tightening force of aviation high lock nuts, the threaded collars used on aircraft.
It covers locking torque, breakaway torque, torque-off and preload, and defines each of them: the maximum torque while the nut is run down onto the interlayer, the minimum torque in the loosening direction, the torque at which the break-neck groove shears off, and the axial load carried by the test interlayer once that groove has sheared.
Testing is done on a torsion-tension machine, or equipment of equivalent precision, whose torque measuring characteristics have been verified under JJG 269 to accuracy class 1; the bolt mated with the nut during the test is called the test mandrel. Issued on 30 December 2022, it has applied since 1 April 2023.
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Document preview — GB/T 42252-2022
National Standard of the People's Republic of China
- ICS
- 49.030.99
- Classification
- V 20
Issued by: State Administration for Market Regulation; Standardization Administration of the PRC
Contents
- Foreword
- 1 Scope
- 2 Normative references
- 3 Terms and Definitions
- 4 General requirements
Foreword
This document is in accordance with the provisions of GB/T 1.1-2020 "Guidelines for Standardization Work Part 1: Structure and Drafting Rules for Standardization Documents" drafting.
1 Scope
This document describes the test method for torque and preload of high lock nuts used in aviation.
This document is applicable to the testing of locking torque, loosening torque, breaking torque and pre-tightening force of high lock nuts used in aviation.
2 Normative references
The contents of the following documents constitute the essential provisions of this document through normative references in the text. Among them, dated references For documents, only the version corresponding to the date is applicable to this document; for undated reference documents, the latest version (including all amendments) is applicable to this document.
JJG269 Verification Regulations for Torsion Testing Machine
3 Terms and Definitions
The following terms and definitions apply to this document.
3.1 Locking torque
The high lock nut is screwed into the test mandrel until it touches the interlayer, the maximum torque during the whole process.
3.2 Breakaway torque
The minimum torque at which a high lock nut is turned in the loosening direction.
3.3 Torque off torque
torque-off Torque when the high lock nut is screwed into the test mandrel to make the broken neck groove of the high lock nut break.
3.4 Preload
In the process of screwing the high lock nut into the test mandrel, the axial load borne by the test interlayer after the broken neck groove is twisted off.
3.5 Test mandrel
testbolt Bolts used in conjunction with high lock nuts during the test.
4 General requirements
Note: The loosening torque should be measured when the broken neck groove of the high lock nut is twisted off and the axial load is removed.
4.1 Test equipment
High lock nut torque and pre-tightening force tests shall be carried out with a torsion-tension testing machine or testing equipment of equivalent precision. The torsion testing machine should be According to the provisions of JJG269, the verification of torque measurement characteristics shall be carried out. The verification results shall meet the accuracy level 1.
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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 15 pages — is available in the English PDF.
Referenced standards
Normative references
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JJG 269-2006 — Verification Regulation of Torsion Testing Machines
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