Vibrations

[Hotscam]

We already have 30 hours on our 12 in a months and couple of thousand miles. She's great and very few problems.

I do however have very annoying vibrations starting near about 105 knots.
Very difficult to find where these come from.
When I idle the engine and dive to keep the speed above 105 it continues to vibrate so it seems to be airflow speed related.
I would say its the wings but it is very difficult to tell directions.

Anybody else experiencing this ?

 

[Geico266]

Do you have wheel pants on?

Are the wheels balanced?

Try applying the brakes in flight?

 

[Hotscam]

Yes, wheel pants are on and pushing the brakes makes no difference

 

[Geico266]

Yes, wheel pants are on and pushing the brakes makes no difference

Could be the front wheel?


Try balancing the front tire and see if the makes any difference. Or take the front wheel pant off and fly to see if it changes.


The 3 RV12's I have flown have not had any vibrations.


Keep us posted with the results.

 

[BigJohn]

Jack,

This sounds very annoying! I wish you the best in finding the source. I'm thinking it is some part of the structure, possibly skin, setting up a resonant vibration at the higher airflow. Try going all around the aiplane, on the ground, and checking every surface for "oil-canning" or any kind of movement, to see if you can replicate the sound. I had a similar problem early on, where the edge of my lower cowl was in contact with the edge of the matching skin, and a noise emanated from that spot at certain engine RPM's.

Let us know what you find.

John

 

[JBPILOT]

Hey Jack - -

If the front wheel spins fairly easily, you need more torque on the front axle. I had that issue. Found out the front wheel was spinning. Put more torque on the front axle bolt, until it does not turn easily. Should solve it.

John Bender
402.9 hours as of 7-12-12

 

[Hotscam]

Problem solved

None if the helpful from VAF seemed to result in improvement.
I did the modification submitted bij VAN's regaring the intercom ground wire causing noise on the audio.
For this I had to open the instrument bay and I noticed the vibrations had increased.
I pulled the forward canopy bar firmly down which stopped the noise completely.
It seems that although it is a tight fit between the bay top and canopy slab the fast flowing air makes it flutter.
I did put some sticky 1/16 soft rubber tape in between and problem completely solved. Tested up to 125 knots and quiet.

Quite happy and thank for Y'all help

 

[BigJohn]

..............I did the modification submitted bij VAN's regaring the intercom ground wire causing noise on the audio................

Jack,

What mod are you referring to? I have intercom noise but am not aware of any mod.

John

 

[Gagarin737]

Jack,

What mod are you referring to? I have intercom noise but am not aware of any mod.

John

Dear RV-12 Skyview owner

We have determined that you may have an early harness manufactured to an obsolete standard, shipped prior to March 2012.

Please check your EFIS harness (WH-00020) to see if it has a wire running from Pin 30 on the 37 pin SVD 1000 EFIS connector to Pin 28 on the 30 pin AV-50000A connector. See drawing 42C-03.

If it does, remove this wire or cut it and heat shrink the ends to break the connection. You can access the connectors quite easily by removing the EFIS screen from the panel. Although this is simply an extra ground wire we have found that it can cause unwanted noise in the audio system, and later harnesses do not have it.

Apologies for the inconvenience.

Vans

Just some extra info; Jack used the prefab canopy skirt instead of the epoxy layup.

 

[Hotscam]

I had a mail from VAN's i had to remove the ground wire from pin 30 of the 37p EFIS cinnector as this may cause noise on the intercom.
This seems to be wrong on a number of shipments (all mailed individually by VAN's).
I had very little noise and the mod changed nothing.
If you did not get the mail its not in your system