Which condition would indicate that air hoses require inspection or replacement?

The condition indicating that air hoses require inspection or replacement is a loss of air pressure during operation. This situation signifies that there may be a leak within the air system, which can lead to inadequate braking performance. A drop in air pressure can affect the entire air brake system's efficiency, leading to safety risks. Therefore, if there is a noticeable loss of air pressure while the system is operating, it indicates that the integrity of the air hoses may be compromised, warranting immediate inspection or replacement.

Consistent pressure levels, while generally desirable, do not in themselves indicate potential issues with the air hoses. Softening of the hose material can certainly be a sign of deterioration, and secure routing is important for proper operation, but neither of these conditions directly reflects the immediate operational concern as effectively as the loss of air pressure.