transientair
Active Member
I have an RV-14A and I am at the point of determining the error of my IAS. I have done several tests and input the data into a spreadsheet calculator generously published by Kit Planes. Following several tests, my IAS appears to read 8-9 knots fast at cruise speeds.
My EFIS is an Advanced 5600T with both a primary and backup Dynon ADAHRs. I have the Dynon heated pitot tube with AOA mounted under the left wing. The ADAHRs are also mounted in the left wing using the mount built into the wing as part of the RV-14 wing design. Two air lines from the pitot (pitot and AOA) run to the ADAHRs and one line for the static runs from behind the fuselage bulkhead where the static ports are mounted on each side of the rear fuselage. I used the Cleaveland static ports (revised domed version). I do not have an alternate air static port in the flight deck.
My first clue that the IAS read high was that no matter what direction I would fly, the EFIS almost always shows a headwind at cruise speeds. Interestingly, when I perform stalls, the IAS at stall is as expected. So, the error is not the same across all speed ranges. Additionally, when I open or close the fresh air vents, the VSI will momentarily show 150-foot climb or descent, depending on if I am opening or closing the vents. So, my thought is or was that there must be a static line leak.
To that, I have replaced all the static line tubing and fittings. All the tubing ends have clean flat cuts to ensure adequate seating. I have also tried both the push in and nylo-seal (with inserts) connections. I pressurized the lines from the ADAHRS (disconnected from the ADAHRS) and sprayed soapy water on all the connections to see any visual evidence of a leak. There were none. I have not tried a manometer.
Also, to ensure the ADAHRs were calibrated, I selected zero pressure offsets in the EFIS settings when I had the plane parked in an enclosed hangar.
I could send in the ADAHRs to be bench tested, but maybe there’s something else I have not tried yet?
My EFIS is an Advanced 5600T with both a primary and backup Dynon ADAHRs. I have the Dynon heated pitot tube with AOA mounted under the left wing. The ADAHRs are also mounted in the left wing using the mount built into the wing as part of the RV-14 wing design. Two air lines from the pitot (pitot and AOA) run to the ADAHRs and one line for the static runs from behind the fuselage bulkhead where the static ports are mounted on each side of the rear fuselage. I used the Cleaveland static ports (revised domed version). I do not have an alternate air static port in the flight deck.
My first clue that the IAS read high was that no matter what direction I would fly, the EFIS almost always shows a headwind at cruise speeds. Interestingly, when I perform stalls, the IAS at stall is as expected. So, the error is not the same across all speed ranges. Additionally, when I open or close the fresh air vents, the VSI will momentarily show 150-foot climb or descent, depending on if I am opening or closing the vents. So, my thought is or was that there must be a static line leak.
To that, I have replaced all the static line tubing and fittings. All the tubing ends have clean flat cuts to ensure adequate seating. I have also tried both the push in and nylo-seal (with inserts) connections. I pressurized the lines from the ADAHRS (disconnected from the ADAHRS) and sprayed soapy water on all the connections to see any visual evidence of a leak. There were none. I have not tried a manometer.
Also, to ensure the ADAHRs were calibrated, I selected zero pressure offsets in the EFIS settings when I had the plane parked in an enclosed hangar.
I could send in the ADAHRs to be bench tested, but maybe there’s something else I have not tried yet?