Definition
In aircraft systems, a series of connected components or events in which each link depends on the one before it, so that the failure of any single link can interrupt the function of the whole. The term is used to describe both physical mechanical linkages (such as a chain of gears or pulleys transmitting motion) and conceptual sequences (such as a chain of events leading to a system failure or accident).
Plain English
A set of parts or steps connected in order, where each one depends on the one before it. If one part breaks or one step goes wrong, the whole sequence is affected.
Context Anchor
Seen in aircraft systems discussions where the handbook describes how mechanical force or motion is transferred between parts.
Derivation
From Latin catena, meaning a series of connected links. The image is the same in aviation: links joined end-to-end, where the strength of the whole depends on the weakest link.
Why Pilots Care
Unsecured aircraft can sustain serious damage or become a hazard to others during high winds or sudden gusts.
Analogy
A bicycle chain is the familiar example: the pedals turn one wheel, the chain carries that motion, and the rear wheel turns.
Intuition Check
Do not read “chains” here as a general idea of connected events. In aircraft systems, it means actual linked metal parts used to transfer motion or force.
Example Sentence 1
The instructor explained that most accidents are the result of a chain of small mistakes, not a single failure.
Example Sentence 2
Before takeoff the student removed the chains from the main landing gear and stowed them in the baggage compartment.