alignment of the magnetometer

[lux wrangler]

I have dual Decks and I am aligning the magnetometers to the Decks. The manual calls for less than 0.2 degrees variance in pitch and roll. One of the Decks is very true when comparing the front face of the unit to its chassis top surface, but the second unit is out in pitch when comparing the front face to its chassis top surface. I have not quantified the amount, but it is a significant amount of the total tolerance allowed. While I could go to the trouble of measuring the extent of variance in squareness from top to front, my question is: what surface should I be using to measure the alignment of the EFIS to the magnetometer? Can I just use the top surface of each component?

[Trevor Conroy]

You could use the longerons as a reference point....or the easiest thing would be to use a digital level and ensure the magnetometer(s) are at the same angle of the EFIS top case. In most RV's, the EFIS top case will be a about 8 degrees off level.