Torque values for tightening aircraft nuts and bolts are related to threads that are

• A. Lubricated threads
• B. Clean, dry threads
• C. Painted threads
• D. Rusted threads

Answer: (B)

Torque values for tightening aircraft fasteners depend on how much friction there is between the threads. The specs are calibrated for clean, dry threads, which provide a known and repeatable friction level. If threads are lubricated, friction drops, so the same torque would produce a higher clamp load than intended; applying the dry-thread torque could over-tighten. If threads are painted, dirty, or rusted, friction changes unpredictably and can prevent proper seating or cause binding, leading to an incorrect preload or damage. So the standard torque values are given for clean, dry threads to ensure the intended clamping force is achieved reliably.