Final answer:
A liquid lock in an aircraft engine cylinder is caused by excessive liquid accumulation, preventing the piston from moving. To clear it, remove the affected spark plug and manually turn over the engine. Preventive measures include correct oil levels and proper aircraft positioning.
Step-by-step explanation:
Understanding Liquid Lock in Aircraft Engines
A liquid lock occurs in the cylinder of an aircraft engine when an excessive amount of liquid, usually oil or fuel, accumulates and prevents the piston from moving. This happens because the liquid is incompressible, unlike air, which can be compressed. When a cold engine is started, the oil is often too thick, which can cause a liquid lock. However, the issue you are referring to seems to involve liquid directly entering the cylinder rather than viscosity issues.
To clear a liquid lock, the affected cylinder's spark plug should be removed to allow the liquid to escape as the engine is manually turned over. This process should be done cautiously to avoid any damage to the engine. It's essential not to force the engine to turn over using the starter motor when a liquid lock is suspected because it can lead to severe engine damage, such as bending the connecting rods.
Preventive measures include avoiding overfilling of oil and ensuring proper aircraft leveling when parked to prevent oil from flowing into the cylinders. Regular maintenance checks can also help identify and address any issues that may lead to a liquid lock.