A Fowler flap is a high-lift device that deploys aft on tracks to increase the wing's surface area before it deflects downward to increase camber. This dual action provides a massive increase in lift with a relatively small drag penalty during the initial extension. Widebody commercial jets heavily rely on them to achieve safe takeoff and landing speeds despite their massive weight.
The right outboard Fowler flap is jamming on the track during the retraction cycle.
Because they physically extend the chord of the wing, Fowler flaps create a noticeable pitch-down moment when deployed, requiring the pilot or autopilot to trim the nose up.
Related terms
Flap
A hinged surface on the trailing edge of an aircraft wing used to increase lift and drag.
Trailing edge
The rearmost margin of an airfoil where the upper and lower airflows rejoin.
Krueger flap
A hinged lift-enhancement device mounted on the lower surface of an aircraft wing's leading edge.
Fairey-Youngman flap
The Fairey-Youngman flap is an aircraft wing flap that drops down and moves aft before rotating.