Definition
The principal spanwise structural member of an aircraft wing, stabilizer, or control surface. The spar runs from root to tip and carries the bending and torsional loads created by lift, weight, and maneuvering forces. Ribs and skin attach to the spar to form the completed surface.
Plain English
The main lengthwise beam inside a wing. It is the strong backbone that holds the wing together and carries the weight of the aircraft in flight.
Context Anchor
Seen in aircraft structure descriptions, inspection reports, maintenance records, and damage discussions.
Derivation
From Middle English 'sparre,' meaning a wooden pole or rafter. The original meaning carries directly into aviation: a long, strong beam that supports a structure -- in this case, the wing.
Why Pilots Care
The spar is the primary load-bearing element; cracks or damage can compromise wing strength and flight safety.
Analogy
A spar is like the main beam in a roof: you may not see it from the outside, but it carries a major part of the load.
Intuition Check
Spar does not mean “to argue” here. In aircraft structure, it means the main internal beam that carries flight loads.
Example Sentence 1
After the hard landing, the mechanic inspected the wing spar for any signs of bending or cracking before returning the aircraft to service.
Example Sentence 2
Reinforced spars allowed the new trainer to handle higher maneuver loads.