Thread: ASI PROBLEM!!!

Hi Guys,

Installed a mechanical ASI as a backup to my dynon 180.

The problem is that the uma (flightdesign model) 2 1/4" is reading approx 20kts slower than the dynon asi and my gps.

When i first installed the uma asi i connected to dynon pitot tube via a t-piece and the static port was connected, at this time the reading was 20-25kts of a difference, i flew N,S,E,W @ 100kts on the dynon and gps. The uma asi was reading 75-80kts. However when on final the all the speeds where the same (60kts).

I then connected to the static also, there was a slight improvement (20kts of a diff) and all pretty much the same on final (60kts).

Has anyone got any suggestions to what maybe the problem??

I do realize that they will not read the same, but 20 kts is a big difference!!!

thanks in advance

neil

depending on altitude I get up to 8 knots difference between dynon and FDIAS, but my dynon reads lower. The difference gets smaller at lower speeds (makes sense as they both agree at zero). WF

Hi,

I've just taken the asi out and packaged it up to go back to uma.

i tink its faulty!!!!

thanks neil

Hi,
My backup UMA was reading about 15 knots slow at 100Kt. Well, the Dynon
was in MPH mode, the UMA was knots. UMA was right.
Be sure to check your D100 display setup.

Bill Mc, N248CT

Hi Bill,

That was one of the 1st things i checked. I think it's the uma asi as the needle was reading 40kts instead of 0kts when on the ground.

its away back to uma as it is under warranty

thanks neil

Got my ASI back from UMA yesterday and installed it today, So it looks ok ie. its reading 0kts. They said that some diaphram had fell off!

let know how i get on once weather improves

neil