SV 1000 Attitude Indicator Problem

[Edwardoc]

This is a fairly new install of the SV 1000 in an RV-8. A single ADAHARS is installed behind the rear baggage compartment and the GPS in installed under the cowling forward of the firewall. I have flown approximately 3 hours on the system before leaving for Sun n Fun. I flew 13 hours over the course of a week and ADAHARS and A/P were working perfectly. Then on the first flight yesterday to return home from Alabama, I engaged the roll axis of the autopilot and it commanded a slow role to the right and then reversed and continued to roll left. I engaged it several times and it did this every time and would roll inverted if not disengaged. Altitude hold worked fine. Shortly after attempting to engage the roll axis, I noticed the attitude display seemed to be lagging the actual attitude of the aircraft. On a slow turn to the left or right the attitude indicator would show a roll in the opposite direction and then slowely correct to the proper roll indication. On roll out from the turn, the attitude indicator would continue to show a roll attitude for about 5 sec and then it would slowly roll out to wings level. During a rapid roll into a turn, it would roll opposite direction and the pitch attitude would pitch up 15 or 20 degrees and then slowly return to the correct pitch and roll attitude. It was completely unusable for IFR had it been required. The rear baggage compartment was loaded the same as previous flights so nothing could have been interfering. What it acted like was procession in both pitch and roll axis. The GPS display and system worked fine. I refueled and on second flight it did the same thing. I did not turn it off and recycle as I did not want to take a chance on it failing completely before getting home. Before I fly again I wanted to see if there was any history of something like this happening to others.
Any ideas as this system is less then a two months old and less the 30 hours flying on the system. I will say I have not done the Heading Calibration yet but heading has been right on and it worked fine on about 8-10 flights before this started. :-[

 

[dynonsupport]

A few preliminary questions:

1) Does IAS appear to behave properly?
2) Is attitude correct on the ground? Ie, if you have a taildragger, does it correctly show a nose up attitude on the ground? (this is affected by the pitch adjust setting). If you have a tricycle geared airplane, does it show more or less level?
3) Is the ADAHRS mounted parallel to the pitch axis of the aircraft, and are the tabs down, and the pitot/static connections pointed forward?

Just looking for the "easy" stuff first.
3)

 

[Edwardoc]

Airspeed and altitude readings were correct in flight and behaved as expected. Attitude is correct on the ground and when it settles down while flying straight and level it indicated the same attitude it did when it was working correctly on the previous 9 flights. When steady it also indicated the correct heading. When pitch changes were made in flight it would respond correctly in a wings level pitch change. However a rapid roll would cause it to indicate an immediate 20-25 degree pitch up. The ADAHRS is mounted up and lines are forward. As I mentioned, it worked perfectly on the previous 9 flights in all aspects including some acro on the first test flight. It is mounted as parallel as I could get it and without doing the calibration the heading is within 1 degree of all runways I have used. I lined up on a compass rose in the cardinal directions when I first installed the system and it was pretty close to all the headings. I just had not taken the time to fine tune using the calibration procedure yet. But since it worked on the first 9 flights and headings and attitudes were all correct I was in no hurry to do it until I got back from Florida.
I will power it up tomorrow and test fly to see if anything is any different. I'll also do the calibration if I get a chance before flying.

 

[Edwardoc]

Took everything out of baggage compartment, did the heading calibration and went flying. All worked normal. I had an odyssey 12 volt battery in its box on the floor of the comparent over 3 feet away from the adhars but maybe it was causing the problem. Anyway it worked today and A/P worked fine. ;D

 

[dynonsupport]

So the magnetic sensors do not affect the attitude in any way, but very abrupt maneuvers could (<150 deg/sec) will exceed the unit's attitude capability, though in this case you should see the "attitude recovering" message. In normal maneuvering, if pitch or roll are significantly wrong and if none of the problems I outlined above are present, there may be an issue with your ADAHRS sensors that we'd need to see the ADAHRS to address. You should get in touch with our technical support team at 425-402-0433 or support at dynonavionics dot com.