Unless otherwise specified or required, aircraft bolts should be installed so that the bolt head is

Unless otherwise specified or required, aircraft bolts should be installed so that the bolt head is

• A. Upward, or in a forward direction
• B. Downward, or toward the tail
• C. Angled to 45 degrees
• D. Random orientation

Answer: (A)

Bolts in aircraft joints are oriented to help keep them tight under vibration and make it easy to verify their condition. When the bolt head is positioned upward or toward the forward direction, the load and vibration in flight tend to work against loosening rather than promoting it. This orientation helps the clamping force stay applied and reduces the chance that the nut will back off over time. It also places the bolt head in a position that is easier to inspect visually, so you can readily confirm that the fastener remains in place and tight. If the head were down or aft, vibration could more readily allow the nut to loosen and the head would be harder to check, increasing the risk of an unnoticed looseness.

Bolts in aircraft joints are oriented to help keep them tight under vibration and make it easy to verify their condition. When the bolt head is positioned upward or toward the forward direction, the load and vibration in flight tend to work against loosening rather than promoting it. This orientation helps the clamping force stay applied and reduces the chance that the nut will back off over time. It also places the bolt head in a position that is easier to inspect visually, so you can readily confirm that the fastener remains in place and tight. If the head were down or aft, vibration could more readily allow the nut to loosen and the head would be harder to check, increasing the risk of an unnoticed looseness.