What loading should be avoided when using a self-locking nut on an aircraft bolt?

What loading should be avoided when using a self-locking nut on an aircraft bolt?

• A. Rotational forces
• B. Axial compression
• C. Shear forces
• D. Torsional loads

Answer: (A)

Self-locking nuts rely on friction to keep the nut from loosening once it’s seated. The locking effect is defeated if a load tends to twist the nut around the bolt after installation. So any rotational or torsional force applied to the nut that would turn it on the bolt should be avoided, because it can overcome the prevailing torque and cause the nut to loosen. Axial compression, which clamps the joint, is the intended load for these nuts, and while the joint may experience shear in the bolt elsewhere, the primary concern for self-locking nuts is preventing rotation about the bolt axis.

Self-locking nuts rely on friction to keep the nut from loosening once it’s seated. The locking effect is defeated if a load tends to twist the nut around the bolt after installation. So any rotational or torsional force applied to the nut that would turn it on the bolt should be avoided, because it can overcome the prevailing torque and cause the nut to loosen. Axial compression, which clamps the joint, is the intended load for these nuts, and while the joint may experience shear in the bolt elsewhere, the primary concern for self-locking nuts is preventing rotation about the bolt axis.