BS 2A 122; 2A 123; 2A 124:1981

Foreword
Specification
Section one. General requirement
1. Scope
2. Definitions
3. Design and dimensions
4. Material and manufacture
5. Freedom from defects
6. Protective coating
7. Screw threads
8. Identification and marking
Section two. Inspection and testing
9. Qualification approval
10. Production batch acceptance
11. Inspection of samples
12. Testing of samples
13. Test bolts
14. Torque test
15. Bolt tolerance test
16. Endurance test
17. Clinching test
18. High temperature test
19. Low temperature test
Appendices
A. Equipment for testing clinch nuts
B. Fitting of aircraft clinch nuts
Tables
1. Unscrewing torque
2. Minimum torque to turn clinched nut in plate
3. British Standard numbers and materials for clinch
     nuts (Unified threads) for aircraft
4. Dimensions and part numbers of clinch nuts (Unified
     threads) for aircraft
5. Calibration of spring balances for torque and
     torsional strength tests
6. Dimensions for high limit and low limit test bolts
7. Assembling tool dimensions
Figures
1. Dimensions of clinch nuts
2. Torque testing machine
3. Dimensions for high limit and low limit test bolts
4. Recommended method of clinching

Specifies the dimensions, material, finish, testing and identification of aircraft clinch nuts with Unified threads. According to the materials used in their construction the clinch nuts are suitable for use at sustained temperatures within the ranges: -75 to +200 Degrees C - Cadmium plated steel nuts and -75 to + 125 Degrees C - Aluminium alloy, brass or bronze nuts. All nuts are capable of remaining effective for servicing operations at -40 Degrees C. Includes equipment for testing clinch nuts and fitting of aircraft clinch nuts. Illustrates dimensions of clinch nuts, torque testing machine, dimensions for high limit and low limit test bolts and recommended method of clinching.

These British Standards cover the dimensions, material, finish, testing and identification of aircraft clinch nuts with Unified threads. According to the materials used in their construction the clinch nuts are classified as satisfactory for use at sustained temperatures within the following ranges:

1. −75°C to +200°C - Cadmium plated steel nuts;
2. −75°C to +125°C - Aluminium alloy, brass or bronze nuts.

NOTE. All nuts are capable of remaining effective for servicing operations at −40°C.