What is the maximum allowable grain slope in aircraft wood?

The maximum allowable grain slope in aircraft wood is significant because it directly affects the material's strength and performance. The 15:1 ratio indicates that for every 15 units of length along the grain, the slope can only rise or fall by a maximum of one unit. This restriction is critical as it helps ensure that wood maintains its structural integrity and does not compromise the safety and reliability of the aircraft.

When the grain slope exceeds this ratio, the wood may exhibit weaker characteristics, leading to potential failure under load due to improper alignment of the fibers. This guideline is particularly important in aviation applications, where safety demands that all materials, including wood, must meet stringent standards. Therefore, adhering to a maximum grain slope of 15:1 helps ensure that the wood used in aircraft structures remains robust and capable of withstanding the stresses encountered during flight.