Definition
A central hub-and-arm component in a fuel injection system, typically mounted on top of the engine, that receives metered fuel from the fuel control unit and distributes it equally through individual fuel lines to each cylinder's injector nozzle.
Plain English
A small fitting on top of the engine that splits the fuel coming in from one line and sends an equal share out to each cylinder through its own line.
Context Anchor
Seen in aircraft maintenance discussions, especially around piston-engine fuel-injection systems and engine troubleshooting.
Derivation
Named for its visual resemblance to a spider — a central body with multiple thin lines radiating outward, one to each cylinder.
Why Pilots Care
If a fuel line at the spider clogs or leaks, one cylinder may run lean, run rough, or stop firing. Recognizing the spider helps pilots and mechanics trace fuel flow problems and uneven cylinder performance.
Analogy
Think of one garden hose feeding a small splitter, with several smaller hoses coming out of it. The splitter is doing the same basic job as a spider: one supply in, several paths out.
Intuition Check
Do not read spider as an insect here. In aircraft use, it means a central part with several lines, arms, or passages spreading outward.
Example Sentence 1
The mechanic removed the spider to inspect the fuel distribution lines for blockage.
Example Sentence 2
The new blades were aligned and secured to the spider before the dome was reinstalled.