What are the flap trak fairings on an airliner wing actually for ?

Question

And what's the main purpose of the fuel jettison under the flap track fairings ? I see some sort of air being blown out of it just before touching down onto the runway

Answer 1

They are there to produce optimum aerodynamics to reduce fuel usage. Fuel jettison is to dump fuel to reduce the landing weight of the aircraft which is much lower than the takeoff weight. More than likely wht you saw condensation that was built up inside the fairing.

Answer 2

Fuel jettison nozzles are typically hard mounted to the wing, not to a moving part. I've mostly seen them between the flaps and ailerons. It's just a piece you don't want moving around.

Maybe what you saw was a water vapor trail caused by flap fairings creating wake vorticies in the slip stream on landing. Happens alot in humid environments.

Answer 3

Place for the A&Ps to hide tools, parts, dirty magazines and beers.

Answer 4

I have never seen a fuel jettison port under a flap track.

I dont know what you are seeing but flap track fairings are for aerodynamics.

Answer 5

There are a lot of fairings around actuators and flight controls on wing and tail surfaces.  all these are to decrease the drag around the struts and actuators.  Gaps between the alerons and the wing, between the elevators and the horz. stabilizor and the rudder and vert stabilizer.  all these gaps add drag, because they allow air to penetrate the boundary layer on these surfaces.

by closing these gaps, you reduce the turbulence on the surface and allow for more lift.  

by adding flap seals and other gap seals, you can improve the top end performance as well as lower the stall speed, making for a safer and more cost efficient plane.

Answer 6

Those fairings are to reduce drag. What your seeing is the vortices's's coming of the end of the flap and also off the wing tip too if you look. Certain aircraft will generate 4 vortices on landing, outboard flaps and tips.  I am sure it just looked like a fuel dump from your angle. They would never do that on final approach.

Answer 7

They are what it looks like they are for.  They serve to streamline the projecting flap tracks and actuators to increase the performance of the airplane.

Fuel dumps are located in various places, though I have never seen them exactly where you describe.  They are used--only when there is no alternative--to lighten the airplane by jettisoning fuel.

Answer 8

they would probably not dump fuel just before touching down.  Perhaps that's a vapor trail you are seeing.  What type of aircraft was it?