In hindsight, I am not sure why I have been secretly dreading the calibration process for our G3X system, but the great news is we accomplished it all without a hitch today. A few things probably contributed to my worry about this phase of the installation project. First, the instructions are incredibly detailed, hinting that the process is complex and requires lots of steps to go absolutely perfect. Well, it is true that they are long ? but once you get down to actually executing them, they really aren?t all that complicated! And, in fact, you can pretty much do without the manual in the cockpit ? everything you need to know is explained on screen as the software steps you through the process. The manual has lots of pages because it has screen shot after screen shot to walk you through ? this is good stuff to read in advance to prepare, but once you get into it, no sweat ? just read the screen and do what it says!
Second on the worry list was the fact that our RV-3 is very small and compact, and there are numerous warning sin the Garmin manuals regarding placement of the magnetometer near ANYTHING that might consist of matter?. Well, conductive or magnetic matter to be exact, but as I have heard it said by some VERY knowledgeable folks, if you try to follow the instructions exactly, you can?t install the magnetometer on an airplane?anywhere! And unless the magnetometer calibrates, you get the feeling that you?ll be constantly flying with a warning message plastered on the PFD. OK, so maybe the writers went a little overboard with the warnings, because even though our magnetometer is installed on the tiny aft deck of the -3, surrounded by tail attachment bolts and close to the elevator trim servo, the calibration went like clockwork ? no issues. Before you get to the calibration, in fact, you do a ?magnetic interference test? which checks the system as you move controls and turn lights on and off. I did this at the end of our asphalt runway (no rebar underneath), and got really small deviations in the onscreen display ? very reassuring.
I guess the third thing that had me nervous was the fact that IF we had experienced any difficulties relating to the magnetometer, I had no idea how we were going to fix it ? short of running things out to the wingtip, which would NOT be fun at this stage of the game.
Like most fears based on the unknown, all of these concerns proved themselves to be groundless. Before taxiing the airplane down to our iron-free calibration zone, we jacked up the tail to a level flight position and ran the AHRS pitch/roll calibration. You basically tell the system how the AHRS is oriented, let things settle, and it figures out the necessary corrections so that it knows the level values for pitch and roll ? very slick (just like aligning an Inertial Memory Unit ? except it is a permanent orientation relative to the airframe). We then started things up and headed down to the run-up pad. Louse brought a surveying compass out from the exploring locker and aligned the airplane to magnetic north by pulling the tail around. While she did the surveying, I did the interference test, wiggling and switching all of the necessary stuff. We then activated the Magnetometer Calibration routine, and it had us rotate the airplane in yaw in 30 degree increments. It tells you when to move, and when to hold, and for how long ? again, very slick! Like the calibrations I have done on other EFIS?s, you don?t need to be dead on when you start ? as long as you are fairly close to ?North? it figures the exact calibration by itself.
When we were done, we rebooted and pointed down the runway ? we were within 1-2 degrees of the heading determined by the Brunton compass, and that is pretty dang close ? probably as close as we could determine the centerline of the aircraft. I taxied back to home base and the heading on the EFIS didn?t change by a single digit. These calibrations were the final steps in setting up the EFIS, and I can tell you that the sensor package that Garmin provides is first-rate ? all of the engine parameters worked first time, and look to be extremely accurate as well.
Garmin really has a winning process here ? despite the dire warnings and large page count, it really is pretty much goof-proof and easy if you just follow the onscreen instructions. With all those tests complete, the avionics in ?Junior? are ready to go?one more hurdle on the road to first flight!
Paul
Second on the worry list was the fact that our RV-3 is very small and compact, and there are numerous warning sin the Garmin manuals regarding placement of the magnetometer near ANYTHING that might consist of matter?. Well, conductive or magnetic matter to be exact, but as I have heard it said by some VERY knowledgeable folks, if you try to follow the instructions exactly, you can?t install the magnetometer on an airplane?anywhere! And unless the magnetometer calibrates, you get the feeling that you?ll be constantly flying with a warning message plastered on the PFD. OK, so maybe the writers went a little overboard with the warnings, because even though our magnetometer is installed on the tiny aft deck of the -3, surrounded by tail attachment bolts and close to the elevator trim servo, the calibration went like clockwork ? no issues. Before you get to the calibration, in fact, you do a ?magnetic interference test? which checks the system as you move controls and turn lights on and off. I did this at the end of our asphalt runway (no rebar underneath), and got really small deviations in the onscreen display ? very reassuring.
I guess the third thing that had me nervous was the fact that IF we had experienced any difficulties relating to the magnetometer, I had no idea how we were going to fix it ? short of running things out to the wingtip, which would NOT be fun at this stage of the game.
Like most fears based on the unknown, all of these concerns proved themselves to be groundless. Before taxiing the airplane down to our iron-free calibration zone, we jacked up the tail to a level flight position and ran the AHRS pitch/roll calibration. You basically tell the system how the AHRS is oriented, let things settle, and it figures out the necessary corrections so that it knows the level values for pitch and roll ? very slick (just like aligning an Inertial Memory Unit ? except it is a permanent orientation relative to the airframe). We then started things up and headed down to the run-up pad. Louse brought a surveying compass out from the exploring locker and aligned the airplane to magnetic north by pulling the tail around. While she did the surveying, I did the interference test, wiggling and switching all of the necessary stuff. We then activated the Magnetometer Calibration routine, and it had us rotate the airplane in yaw in 30 degree increments. It tells you when to move, and when to hold, and for how long ? again, very slick! Like the calibrations I have done on other EFIS?s, you don?t need to be dead on when you start ? as long as you are fairly close to ?North? it figures the exact calibration by itself.
When we were done, we rebooted and pointed down the runway ? we were within 1-2 degrees of the heading determined by the Brunton compass, and that is pretty dang close ? probably as close as we could determine the centerline of the aircraft. I taxied back to home base and the heading on the EFIS didn?t change by a single digit. These calibrations were the final steps in setting up the EFIS, and I can tell you that the sensor package that Garmin provides is first-rate ? all of the engine parameters worked first time, and look to be extremely accurate as well.
Garmin really has a winning process here ? despite the dire warnings and large page count, it really is pretty much goof-proof and easy if you just follow the onscreen instructions. With all those tests complete, the avionics in ?Junior? are ready to go?one more hurdle on the road to first flight!
Paul
