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

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

Answer: (B)

Torque values are a measure of the clamping force produced by turning a fastener, and that force depends on friction at the threads. The tables manufacturers provide assume the threads are clean and dry, so the friction level is standard. If threads are lubricated, friction drops, and the same torque would create more clamping force; you’d use a lower torque to get the same result. Painted, rusted, or otherwise treated threads change friction unpredictably, so the dry-value torque isn’t appropriate unless specified. That’s why, unless told otherwise, the torque values relate to clean, dry threads.