Unless otherwise specified, torque values for tightening aircraft nuts and bolts relate to

Unless otherwise specified, torque values for tightening aircraft nuts and bolts relate to

• A. Clean, dry threads
• B. Clean, lightly oiled threads
• C. Both dry and lightly oiled threads
• D. Threads with lubrication only

Answer: (A)

Torque values are set assuming a predictable friction condition between the threads. When threads are clean and dry, friction is at a standard level, so the published torque will produce the intended clamping force. If lubrication is present, friction drops, and the same torque would yield a greater clamp (or you’d need less torque to reach the same clamp); if there’s dirt or contamination, friction becomes unpredictable and the torque may not produce the correct tension. Since nothing else is specified, the standard assumption is clean, dry threads, which is why that option is the best answer.

Torque values are set assuming a predictable friction condition between the threads. When threads are clean and dry, friction is at a standard level, so the published torque will produce the intended clamping force. If lubrication is present, friction drops, and the same torque would yield a greater clamp (or you’d need less torque to reach the same clamp); if there’s dirt or contamination, friction becomes unpredictable and the torque may not produce the correct tension. Since nothing else is specified, the standard assumption is clean, dry threads, which is why that option is the best answer.