A320 question about flaps vibration

[KrisK]

Hello,

I have a question about the trailing edge flaps on the A320.

I was on a flight this morning. During approach with the flaps extended I noticed the outer trailing edge flap was vibrating. It almost looked as if the flap was loose at the point where it is attached to the wing. It went approximately 3 to 5 centimeters back and forth. Only the part where the inner and outer flap meet was shaking. There was no turbulence. I know that flaps are not fully extended during takeoff but I don't seem to recall seeing any vibration after departure. Is this kind of vibration normal? I have never seen flaps vibrate that much.

Thanks!

[Rainboe]

Flaps do vibrate quite horribly sometimes. The 737 ones do with small flap extensions when speedbrakes are used. You know the designers and builders are well aware of it, but I admit, it is very disconcerting to see. On the VC10, we had a periscope that went up through the rear fuselage roof so you could see the engines and tail. It was a surreal experience watching the whole tail fin shaking backwards and forwards when on training flights we did Dutch rolls (I don't know where the Holland connection came in!). These are slow yaw/roll reversals of large scale. The whole fin would be moving. Not my favorite exercise!

[K.Whyjelly]

Originally Posted by Rainboe

Flaps do vibrate quite horribly sometimes. The 737 ones do with small flap extensions when speedbrakes are used. You know the designers and builders are well aware of it, but I admit, it is very disconcerting to see. On the VC10, we had a periscope that went up through the rear fuselage roof so you could see the engines and tail. It was a surreal experience watching the whole tail fin shaking backwards and forwards when on training flights we did Dutch rolls (I don't know where the Holland connection came in!).

Rainboe..........the term Dutch Roll is used because the motion of the aircraft following its excitation is said to resemble the rhythmical flowing motion of a Dutch skater on a frozen lake!! (Or so my text books told me)

[Rainboe]

Thanks! Of course the tailfin in my post shouold have been written as 'swaying from side to side, rather than backwards and forwards (which would mean you were about to be deceased!). A darn good diverging 'Dutch Roll' rolling each side is absolutely frightening. And doing stalls to stick push on the VC10 in an air test was awful to me. The most frightening flying I ever did, with the memories of the BAC1-11 and 2 Trident accidents (T-tail superstalls) so fresh. The AofA indicator would get to 15 degrees and hover, then the push would go, horns blaring, 95 kts indicated, and you would pitch violently down- which meant you would live! That was the end of any ambitions I may have ever had (which I didn't) to be in any way a 'Test Pilot'! I had been lying in bed on a sunny Sunday morning when they called me out to do that on standby! I hollered about it so loudly afterwards that i think they restricted test flights to volunteers only after that. Not me Baby!

[Final 3 Greens]

I would have thought you would have played 'Ride of the Valkyries' and enjoyed the free white knuckle ride, you wimp

Some years ago, I did the same detail on a Trident sim and whilst spared the emotions caused by my butt being really on the line, was absolutey amazed by the pitch down and altitude loss.

[KrisK]

Rainboe, thanks for enlightening me. And thanks for the explanation of the term "Dutch roll" Whyjelly. By the way I had never heard about super-stalls so I just read an article about it. Doesn't sound like my type of experience. I always thought a regular stall was all there is.