The FlightStream 210 AHRS can be calibrated within ForeFlight Mobile by doing the following:
STEP 1. Tap the AHRS SETTINGS button (gear icon above the fullscreen button) in the attitude display. This will activate the Zero Pitch & Bank mode and a blue Save button will appear in the upper left corner.
STEP 2. Adjust your aircraft so that it is straight and level then tap the Zero Pitch & Bank button to zero the display.
STEP 3. Tap the Save button to save the AHRS calibration.
How to Calibrate AHRS for your Flight Stream 210
NOTE: AHRS calibration should only be performed while in level, unaccelerated flight, or while stationary and level on the ground. Calibrating the device while accelerating or decelerating may result in errors in pitch and bank information.