Vibration

[Grasshopper]

Anyone have an answer to vibration initiated on selection of reflex flap setting?

[Anticept]

Can you feel, or just hear it?

 

How "loose" are the flaps when you move them by hand?

[Grasshopper]

Flaps move about 1/4" by hand, right slightly more than left.

My mechanic discounts this as a cause, but??? It's more feel than noise, through the rudders and airframe, but quite marked as the flaps go up.

I've experimented diving and turning from height with engine off(well short of vne, I hasten to add), absolutely smooth as silk.

Have replaced engine mounts,dynamically balanced prop,checked carby balance and balance tube, replaced CDIs

If I set flaps at much slower speed, vibration is reduced, but becomes more marked as speed builds. Over time, it seems to dissipate somewhat. Am about to replace the two blade prop with a three blade.(It doesn't do to run over taxiway cones)

Any ideas appreciated.

[FlyingMonkey]

Hmm, my flaps are very rigid, no movement by hand in any setting.

[Runtoeat]

Is there a air speed or speed range at which the vibration starts to occur?  Do you feel the vibration with power on?  Do you feel it with power off?

[Grasshopper]

I usually set reflex flaps at 100kts, vibration is quite marked at this speed. If set at say 80 kts, vibration is less. Related to power- more with added power, less on decreased power. Does dissipate over time, but not completely.

[FlyingMonkey]

At 100kt, if you put the flaps back to 0 does the vibration stop?  Does it *only* occur with -6 flaps?  It's a little tricky to test since 100kt  is max speed for 0 flaps.

[Anticept]

There's going to be up to a slight amount of movement due to the construction of the flaps mechanism. I'm still not sure of the vibration you speak of though. Does it sound like a vevuzela? Because I have that vibration and I haven't figured out what the heck that is as it comes and goes.

[Doug G.]

Some have noted noise coming from lose our missing bowlus tape on wings or gear leg fairing. Could that be related. Also, since we have flaperons, do you feel it in the stick?

[ct9000]

I had a similar harshness / vibration on my ctsw with the two blade Neuform . Changed to a three blade cs problem solved . I normally climb at flap 0 then at top of climb 75kt. then select -12 flap then reduce power , it is not as bad .

[Grasshopper]

Thanks for your comments, all. I am about to change to a three blade Nueform. Maybe that will solve the problem. Had a good look at wing root flap connection- all looks good. Very minimal movement on either side.

[Roger Lee]

Neuform's have weights inside the blades down around the base. They can come loose and even cause sever vibration.

[gbigs]

I fly with the factory supplied three-blade Neuform and it flew flawlessly before and after it was taken off completely and reinstalled for the Sport Upgrade.  There are ZERO issues with the prop.  If it comes loose then it's installed incorrectly.

 

I would suspect the cowling on the wheels, the bowlus tape, a loose nut on the engine cowling, a loose door before suspecting an entire wing flap or aileron.  Unless you can physically move the flap and it has a LOT of play.