Warning ACTV ADAHRS Vibration?

[sunfish]

Going through the alert logs after some first engine test runs, the aircraft hasnt flown yet. I notice the ADAHRS Vibration warning every now and again for a few seconds at a time. The ADAHRS is mounted in the rear of the aircraft on a .032 mount I made myself. The engine is a Rotax912 iS. The rpm at warning is about 3800, 4700 and 5700. I'm not sure what to do about it or whether just to ignore it.

Vibration and harmonics I don't understand. I dont want to use rubber mounts for alignment reasons. I guess I could try to stiffen the mount somehow, or maybe I could add a piece of lead sheet to try and dampen the vibration. What do you think?

 

[sunfish]

From what little I have found on the web, I’m going to try and stiffen the mounting area. The mount is just behind an access hatch and it flexes a bit because of the loss of stiffness around the cutout.

 

[sunfish]

Anyone had ADAHRS VIBRATION warning? Any suggestions ?

 

[DBRV10]

Rivet a piece angle across it.

 

[sunfish]

Thanks. I’ll try that. With the diagonal brace I put in, I only get vibration at above 5500rpm. I guess that is acceptable, but I just checked that there is room for another angle, so that is what I’ll do DBRV.

 

[DBRV10]

Sunny,

Also, your mount is mounted to "something" else. Maybe that is where the movement is. I did an installation in a Savvy recently and getting a nice rigid structure was an issue. We had to do some bracing also.

 

[sunfish]

I’m fitting two stiffeners tomorrow. That’s in addition to a diagonal brace. Then I‘ll try another test run.

 

[sunfish]

Stiffeners fitted, waiting for rain to stop......

 

[sunfish]

All fixed. 5700 rpm and no caution messages.