| 摘要 |
<p>Propeller hubs and the hollow inner ends of propeller blades are filled or substantially filled with a liquid so that cracks in the hub wall or the blade wall leading from the interior to the exterior surface provide a pathway for the liquid to flow out to the exterior thereof, thus providing a visual indication of the presence of a crack prior to a catastrophic failure of the part. The liquid may be sealed in the blade or hub or may be carried within the hub as a lubricating fluid, partially or substantially filling the hub. The liquid may contain a dye to enhance visibility even of very small amounts which flow to the surface when the propeller is subjected to centrifugal force. Maintenance personnel and/or operators may then periodically inspect the exterior of the hub and/or blade to check for any evidence of the indicator liquid on the exterior surfaces or on the adjacent aircraft surfaces as a warning of possible incipient crack or fatigue failure.</p> |
