Definition
A failure mode in a stranded electrical cable in which the inner strands (the core) pull back or separate from the outer strands, leaving a weakened section where current must flow through fewer conductors. It commonly occurs at terminal lugs or splices where the cable has been improperly stripped, crimped, or repeatedly flexed.
Plain English
The inside wires of a bundled cable have pulled away from the outside wires, so the cable is thinner and weaker at that spot than it should be.
Context Anchor
Seen during inspection or repair of composite or bonded aircraft panels, control surfaces, and other lightweight aircraft structures.
Derivation
Core comes from the Latin cor, meaning heart or center -- the inner part of something. Separation comes from the Latin separare, to pull apart. Together the term simply names what has happened: the heart of the cable has pulled apart from the rest.
Why Pilots Care
Determines thrust output, fuel efficiency, and noise levels that affect aircraft performance and operating costs.
Analogy
Think of a piece of plywood whose layers have started to come unglued. The outside may still be there, but the piece is no longer as strong as it was designed to be.
Grounding Statement
A panel with core separation may look mostly normal but feel soft, loose, or different from the surrounding area when checked.
Intuition Check
Do not read core separation as just any crack or surface damage. It specifically means the inner support material has come loose from the outer layer it was bonded to.
Example Sentence 1
During the inspection, the technician found core separation just behind the terminal lug and replaced the cable end.
Example Sentence 2
Maintenance crews inspected the fan blades that direct air into the core separation area.