How to detect airspeed faults?


I’m facing a problem last month, on the ground, the elevons are not aligned - the left elevon is up while the right elevon is aligned(mid position) in auto mode or the elevons is moving all the time with airplane on the ground.
If I select manual mode the elevons are perfectly aligned but in auto or FWB the left elevon is always up.
I recalibrate accel, compass, level and I detected only when I enable the airspeed this behavior are happening.
I already know before having 3d fix, there is an oscilation on the elevons, but then 3dfix are achieved this behavior disappear, but in my case the elevons still moving.
I’m suspecting there are something wrong with my airspeed, but the airspeed is measuring the airflow so I don’t know what problem or how can I detect a problem with airspeed.

This is a sample log - the airplane was on the ground, inside a room with no wind, and the elevons are moving all the time.

Thanks for any help.

I don’t think this is something to worry about. When you are on the ground, in any mode other than manual, the airplane tries to fly itself (to some extent). This isn’t something very deterministic, but you can think of it as your plane trying to level itself out, but while having no wind on its wings.
Especially if your I and D gains are significant, you can expect some deviation and jitter in your control surfaces.

Hi George,

the main question is my brother has a same wing and all same structure and all, but on his wing we can’t have this behavior.

You said during this log the aircraft is immobile in your room, right?

If this is the case, then this plot of your airspeed surely shouldn’t be right. There is way too much noise in the airspeed reading which may affect your control loops.

Do you have any idea why this happens? What airspeed sensor do you use?

Hi @Georacer,

I was off this days, sorry. I changed the cables of the airspeed to a shielded cable and I will test tomorrow, this is the last try before replace the airspeed.
I’m using a I2C airspeed 4525DO.