Definition
A type of fiber optic cable in which the optical fibers are loosely bundled inside a protective outer jacket without an internal supporting framework. These cables are flexible and lightweight, and rely on the surrounding jacket and any external mounting hardware for protection and shape, rather than on internal stiffeners or rods.
Plain English
A bundle of glass or plastic light-carrying fibers held together inside a flexible outer covering, with nothing stiff inside to keep it in a fixed shape. It bends easily and takes the shape of wherever it is routed.
Context Anchor
Seen in aircraft maintenance, wiring installation, avionics equipment, and inspection instructions for fiber-optic systems.
Derivation
Fiber comes from a Latin word meaning a thread or filament. Cable refers to several strands or lines grouped together. Rigid means stiff. The phrase points to a cable made of thread-like signal paths that is flexible rather than held in a stiff structure.
Why Pilots Care
A damaged fiber cable can interrupt signals between aircraft electronic systems. Even though pilots may not handle these cables directly, a maintenance issue with them can affect displayed information or system operation.
Analogy
Think of a garden hose full of thin spaghetti strands versus one with a stiff rod inside. The version without the rod flexes freely and routes around corners easily, but it depends on its outer covering for protection.
Intuition Check
Do not read “fiber” here as cloth rope or structural fabric. Here it means fiber-optic strands that carry light signals, and “without rigid structure” means the cable is flexible and needs protection from damage.
Example Sentence 1
The avionics technician routed the fiber cables without rigid structure through the existing wire bundles, since they could bend around the airframe ribs without special supports.
Example Sentence 2
During the inspection the mechanic confirmed that the fiber cables without rigid structure met the bend radius limits for the elevator trim system.