In relation to engine operation, what does hydraulic lock indicate?

Hydraulic lock indicates the presence of fluid in the combustion chambers of an engine. This condition occurs when fuel or oil accumulates in the cylinders, typically as a result of a fuel leak or during engine maintenance procedures. When an attempt is made to start the engine, the piston cannot compress the liquid in the combustion chamber, leading to a potential engine failure or damage if not addressed. This is a critical situation that needs immediate resolution before attempting to start the engine, as the liquid creates a barrier that the piston cannot overcome, unlike gases that can be compressed.

The condition suggests an issue that must be rectified, and it requires addressing the root cause of the fluid presence. Identifying hydraulic lock can help pilots or maintenance crews prevent extensive damage and ensure safe engine operation.