What is a common indicator of mechanical trouble with the aerial device?

Drifting of the aerial device when raised is a significant indicator of mechanical trouble because it suggests that the aerial device is not maintaining its intended position, which could be due to several underlying issues. This drifting could result from hydraulic system failures, such as leaks or loss of pressure, or problems with the mechanical components that control the device's stability. When an aerial device is unable to remain stationary while raised, it poses serious safety risks for operators and nearby personnel, making it crucial to address this issue promptly to avoid accidents or further mechanical damage.

Other indicators, like discolored heat sensors, leaking water, or fluid odors, may point to specific issues but do not directly signify a loss of control or stability in the device, which is critical for safe operation.