Changing iEFIS Lite pressure sender

[rainier]

When weeding out my daily load of spam on this forum (99% from Russian sources) I may have accidentally deleted a post related to changing a pressure sensor on an iEFIS Lite.

If you purchase a replacement sensor you must drill a small hole in the center if the bottom surface of the sensor - this creates a connection between the bottom port and the altimeter sensor on the bottom PCB (static pressure). Ensure once the sensor is fitted that there are no air leaks in that connection (we use a o-ring as seal).

Once everything is working you need to calibrate the airspeed sensor. First start by zeroing the sensor as usual. Then calibrate the "factory calibration" number - this is a percentage (nominally 100%). Us an accurate pressure reference connected such as a pilot static test set. We use calibration speed of 90mph which is about 1/5 span of the pressure range. Allow the sensor to warm up (self-heat) for about 5 minutes to stabilize the internal temperature compensation). Make sure all user calibrations have been removed before you perform the factory calibration. You should end up with a number not outside the 85-115% range - if you can't get that right - there is another problem somewhere.

You can use a water column of 105mm height as calibration reference for 90mph. This is simple to construct with a ruler, a few clear silicon pipes (such as used for fish tanks) and a syringe. You will need one T-piece. Make a U shaped manometer some 20-30cm high on a piece of wood. One end open, the other plug in the t-piece. Here you connect the syringe and the EFIS. Fill the pipe with enough water so you can use the syringe to create the 105mm height difference between the water column in each leg of the U.
It's a crude way of making a calibration reference - but it is very accurate and is an absolute pressure standard and perfectly suited to create the small pressures needed to calibrate any airspeed indicator.