PAP, leak-checking the pitot system with ADAHRS box

[AeroDog]

Following the PAP instructions, with the syringe attached to the pitot tube, the behavior I'm seeing is as if I reversed pitot and static lines on the ADAHRS box (I didn't): If I withdraw the plunger, the altitude displayed on the Skyview increases and the airspeed displayed increases. The altitude shouldn't be affected and the airspeed trend is backward. Could the ADAHRS box be plumbed backward?

Jerre

 

[rcarsey]

It does sound like you're attached to the static port instead. If on the static port.. then withdrawing the plunger (decreasing air pressure) would make the altimeter climb. And the airspeed will also climb because the pitot pressure (ambient pressure) is higher than what is on the static port.. Something is definitely plumbed backwards..

 

[Fisherpd]

You might check the ADAHRS box to make sure it is oriented correctly. It is possible to mount it upside down. (ask me how I know!)

 

[AeroDog]

Following the PAP instructions, with the syringe attached to the pitot tube, the behavior I'm seeing is as if I reversed pitot and static lines on the ADAHRS box (I didn't): If I withdraw the plunger, the altitude displayed on the Skyview increases and the airspeed displayed increases. The altitude shouldn't be affected and the airspeed trend is backward. Could the ADAHRS box be plumbed backward?

Jerre

Update: Upon further scrutiny of page 42c-10 in the KAI, it's clear that the labeling is wrong. The center port on the ADAHRS box is clearly (incorrectly) labeled "static." There's a label to the left saying "pitot" with an arrow pointing to nothing. Looking at the drawing of the line routing, the static line clearly goes to the to the port side and the pitot line goes to the center. The starboard port on the ADAHRS box is the AOA. If the two labels with their arrows are moved to the right an inch or so it'll be correct with pitot pointing to the center port.

Jerre

 

[Fisherpd]

My page 42C-10 was updated 7/27/22 and appears top be correct. (updates are on the Van's site under support)