What is the primary reason for torquing both the bolt and the nut when lock tabs are used?

• A. To achieve correct preload and ensure tab alignment
• B. To save time
• C. To avoid rechecking torque
• D. To reduce bolt wear

Answer: (A)

Lock tabs prevent loosening by locking the fastener in place once the tab is bent into position. Torquing both the bolt and the nut establishes the correct preload in the joint and sets the parts so the locking tab can align properly when bent. With the right preload, the clamp load keeps the joint seated and the tab engages the notch securely, resisting vibration-induced loosening. If only one side is torqued, the clamp load can be off, tab alignment may be improper, and the lock may not hold as intended. The idea is to ensure proper preload and proper tab alignment for a reliable lock, not to save time, skip checks, or reduce wear.