Altimeter discrepancy on Skyview

[airguy]

On Saturday of this weekend I flew in some rain just prior to landing and putting the aircraft away, no problems noted in flight or landing. On Sunday I pulled it out to fly again and noticed that my Skyview Classic with 15.2.0 software was indicated altitude about 400 feet high with the correct altimeter setting. My backup G5 indicated correctly - and they are connected to the same static source. Using my alternate static source made no difference to either instrument, so I am relatively confident the problem is not with my static system itself.

Interestingly, in flight buzzing around the local area it very slowly and smoothly came back into agreement with the G5 over a period of maybe 45 minutes. At this point I'm wondering if my ADAHRS got wet in flight on Saturday and I was seeing the effects until it dried out on Sunday - but I saw no other ADAHRS effects and got no errors on my screen. My ADAHRS is in the tail just forward of my vertical stabilizer and forward of the tail fairing, airflow in the RV's is known to be tail-forward, I suppose it's possible I got some rain under that fairing and it blew forward onto the ADAHRS.

 

[Raymo]

I'd suspect some water was in the line to the AD-AHRS that eventually evaporated. Your alternate static source likely feeds into the same line going to the unit in the tail so it would not make a difference.

 

[airguy]

I'd suspect some water was in the line to the AD-AHRS that eventually evaporated. Your alternate static source likely feeds into the same line going to the unit in the tail so it would not make a difference.

That's possible, though I don't know that I would call it likely, at least not just yet. I have dual static ports with lines that rise up the sides of the fuse to a Tee connection at the top, then it goes from there to a 3-way splitter. One leg of that goes to the Dynon ADAHRS, the other leg goes forward to the Alt Static selector and the G5. I would be surprised if water got high enough in the Tee-configured static connections to get to the ADAHRS without flying in a sideslip for an extended period in the rain and thus providing a pressure differential large enough to push the water up past the Tee connection.

Not saying that couldn't happen, just not ready to call it likely.