Wheel-barrowing

Wheel-barrowing is a problem that may occur when a pilot places excessive forward pressure on the flight controls of an aeroplane with a tricycle gear configuration during takeoff or landing. Forward pressure on the elevator control results in an upward force on the elevator surfaces in the aircraft's tail, thereby transferring weight from the main wheels of the landing gear to the nose wheel. The aircraft becomes as unstable as a wheelbarrow rolling on a single wheel and directional control is compromised.

Depending on the severity of the wheel-barrowing, damage to the aircraft can be quite extensive: The propeller of a single engine airplane may strike the ground, damaging it and the engine. The nose wheel can collapse, as is not at all designed to support the entire weight of the aircraft. A wing can get damaged striking the ground as the aircraft pivots over the nose-wheel and one main wheel.

Wheel-barrowing may also be caused with a tricycle gear when the turn radius is too sharp for the speed of the aircraft on the ground – much like a child on a tricycle taking too sharp a turn. The problem is exacerbated when brakes are applied during the turn.

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Wikipedia