Calibrating torque wrenches. From comment above, "So to answer your question about what standard to calibrate to it depends on the tool manufacture and the standard they used.
"AC 43.12-1B
Section 12-71. TEST EQUIPMENT CALIBRATION STANDARDS.
a. The test equipment calibration standards must be...
From above posts, "I also think Garmin learned a hard lesson from Avidyne in terms of upgrades. They lost a lot of customers to the slide-in Avidyne and I feel like they'll work a lot harder to have a slide-in replacement for the GTN next time"
I'm amazed they didn't learn that lesson decades...