In an FAA safety alert cautioning of temporary loss of heading and attitude display information in Garmin cockpits, the agency outlines steps Garmin has identified to prevent the issue from occurring.
The safety alert for operators (SAFO) is directed at airplanes equipped with the GRS 77/77H attitude heading reference system (AHRS) installed as a key component in the G1000, G900, G600 and G500 avionics systems.
Garmin continues to investigate the issue, which has been reported by a small number of pilots. The avionics maker thinks it may have traced the cause of the display loss to two factors:
1. Moving the aircraft on the ground during the first 10 seconds after turning on power to the AHRS.
2. Magnetic interference introduced near the magnetometers during AHRS initialization (i.e., during the 60 seconds following power up of the AHRS).
Either of these actions can cause "a noticeably drifting heading to be displayed on the PFD prior to takeoff, which may lead to a temporary loss of PFD displayed heading and/or attitude information after takeoff and during climb," Garmin notes.
As a preventative measure, pilots flying with affected gear are being advised not to move the aircraft on the ground during the first 10 seconds after turning on the pilot's and copilot's PFDs. Pilots should also not take off if the heading displayed on the PFD is noticeably drifting. When this occurs, powering down and reinitializing the AHRS normally resolves the condition, Garmin says.
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