hydraulic lock

hydraulic lock

hydraulic lock
Oil or fuel can seep past the piston ring on the lower cylinder of a radial engine, causing hydraulic lock. The pressure of hydraulic lock is identified by an abnormal amount of effort required to rotate the propeller. If a start is attempted under these condition, severe engine damage can result.
i. A condition in which oil drains into the lower cylinders of an engine and leaks past the piston rings to fill the combustion chamber. If this oil is not removed before starting the engine, there is a serious risk of damage to the engine. The propellers are hand-rotated before being hand-cranked to detect this situation.
ii. Refers to the undercarriage that is in a locked state hydraulically (and mechanically).
iii. The use of fluids that are incompressible to prevent the movement of mechanical parts.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved
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