COL

The centre of lift is the point on a wing where the total aerodynamic force acts as if concentrated there. It is not a physical location you can touch, but rather a calculated or measured point that changes with airspeed, angle of attack, and configuration. For a maintenance technician, understanding COL matters because it interacts with the aircraft's centre of gravity (CG) to determine handling characteristics and structural loading.

The COL moves along the chord of the wing as flight conditions change. At low speeds and high angles of attack, it migrates forward (toward the leading edge); at cruise speeds it typically sits around 25 per cent of the chord back from the leading edge. This movement is why a heavy aircraft feels different to fly at low speed than at cruise, and why pilots must respect both minimum and maximum CG limits. The distance between COL and CG determines the aerodynamic stability and the load carried by the tail.

Why this matters in maintenance

Structural loads transmitted through the wing depend partly on where the lift is generated. If the COL moves significantly due to damage, modification, or rigging error, wing root bending moments and local panel stresses will shift accordingly. This is why proper wing alignment and surface condition are not cosmetic concerns; they affect the pressure distribution and thus the effective COL location.

Damage to leading-edge devices, high-lift systems, or control surfaces can alter the effective COL, which is one reason why even apparently minor nose-gear door dents or small surface damage must be evaluated. Similarly, unauthorized modifications to wings, removal of vortex generators, changes to leading-edge cuffs, or unauthorized winglets, shift the COL and invalidate the original structural and aerodynamic certification.

COL is distinct from the centre of pressure, though the terms are sometimes confused. Both describe where forces act, but centre of pressure includes all aerodynamic effects including drag and pitching moment, whereas COL refers specifically to the lifting force. For balance calculations and rigging checks, you use COL; for detailed aerodynamic analysis, you use centre of pressure. Neither appears directly on a weight and balance form, but both are built into the CG limits that do.