KI256 showing slight pitch down at >10000 Ft

[Vref]

Last week I was flying at 11K Ft and my KI256 showed a slight pitch down.though I was level, KFC150 engaged in ATT hold was trying to compensate with a climb...Below 8K Ft all was fine......Roll channel no problem

I am afraid my KI256 is in for a bearing replacement...? It has about 600 Hrs since it last went in according logbooks...

Any thoughts on these symptoms?

thanks

Luc

[Awful_Charlie]

I would suspect the vacuum pump before the gyro, but it is odd the roll is not affected.  If you fancy coming down to Habsheim I've got a spare KI256 you could do a test with.

Good luck finding the cause

Ben

[Vref]

Hi Ben thanks for the offer. . My bird is in Hungary for some maintenance actions I am curious what the findings will be though if they can't identify the pump I may take on your offer, nice area for flying also...

I read once an article that KI256 bearing degradation starts with a pitch down and after a while it will suddenly rather abrupt start indicating a unwanted roll...with all secondary effects if the A/Pis engaged at that time......

thanks

rgds

Luc