Aircraft Maintenance: uAvionix responds to ‘wet compass challenge'
In a recent article, I tackled the question of why we are still using wet compasses in the age of glass panels, challenging the industry to build a better mousetrap. uAvionix answered the call.
The company arrived at EAA AirVenture Oshkosh in Wisconsin with a demonstration product to display.
Although one could argue that a wet compass is the ultimate failsafe instrument, there are many issues with this centuries-old technology:
- Compasses are not very stable heading sources, forcing pilots to compensate for acceleration and deceleration, as well as leading or lagging during turns.
- Accuracy can be poor, especially when affected by nearby electronics. Pilots must compensate by referring to printed deviation cards.
- Compasses are typically located on or near the windscreen, potentially obstructing a critical portion of the pilot’s view.
- They require routine and time-consuming maintenance “compass swings” to reduce accuracy issues, especially after any avionics work.
- Compass fluid eventually leaks or evaporates, requiring additional maintenance.
I’ve known the folks at uAvionix for some time and have been extremely impressed with their ability to produce innovative products in small packages (and small prices to match). I knew that the company already had a tiny, certified magnetometer called AV-MAG that provided magnetic directional data to its AV-30 primary flight display. I also knew that the company had a remarkable little 2-1/4” AV-20 flight instrument that is already certified as a clock and flight timer, and which I use in our Titan T–51D Mustang as a G meter, backup attitude indicator, angle-of-attack (AOA) indicator, voltage meter, and it even has a built-in backup battery.
And so it wasn’t too surprising when my phone rang shortly after the compass article was published. The call was from Shane Woodson, uAvionix’s vice president of general aviation. “I saw your article,” Woodson said. “Let’s talk about your wish list.”
So, what did I wish for? How about a low-cost, 2-1/4” MDI with a built-in clock, timer, G meter, and voltage meter? “See you in Oshkosh,” was Woodson’s slightly coy response.
If you were fortunate enough to make it to EAA AirVenture in July, you probably got to see the result of this lightning-speed project at the uAvionix booth. The preliminary product is called the AV-MDI, and it includes some pretty amazing features:
- 2-1/4” MDI.
- A variety of display options including an arc view, compass rose view, horizontal tape view, and digital view.
- Options that emulate a real compass (turn right – tape moves left), or simplified view (turn right – tape moves right).
- “Snap” feature that marks a selected heading and provides color indications when you turn off course.
- Slip/skid ball display.
Pricing and a formal commitment to production were not available at the time of the show. However, judging by the crowd of pilots standing around the AV-MDI display, I’d say that uAvionix already has a winner on its hands. If this product makes it to market, I’ll be first in line to yank the compass off the top of my panel, clean up my view out of the windscreen, and say goodbye to practicing “Accelerate North, Decelerate South” or “Overturn North, Underturn South”. I’ve already got a place in my office set aside to display the old compass…right next to the wind-up clock I pulled out years ago. Until next time, I hope you and your families remain safe and healthy, and I wish you blue skies.
