What area of a wood spar may not be spliced?

The area of a wood spar that may not be spliced is near the wing attachment fittings. This is due to the significant structural loads and stress concentrations that occur in this region, which are critical for maintaining the overall integrity and strength of the wing structure. Wing attachment fittings are subject to bending, shear, and torsional forces that can adversely affect a splice if not done correctly, leading to potential failure.

In contrast, splicing is more feasible at other locations, such as the mid-span, where the distribution of loads is typically more uniform and less critical. Splicing near control surfaces or at the tail section may also be possible, but again, it requires careful consideration of load distribution and must adhere to strict guidelines to ensure safety and structural integrity. Therefore, the safest and most common practice is to avoid splicing at or near wing attachment fittings.