Not long ago, Duncan Aviation's M2 lost all GPS information and received a number of CAS messages related to these interruptions. TCAS Fail, ADS-B Fail, AHRS 1 and 2 Fail. These CAS messages are normal if all GPS signals are lost.
All of this happened while taxiing in front of one of Duncan Aviation’s maintenance hangars in Lincoln, Nebraska, while the hangar doors were open.
As it turns out, there are GPS and XM repeater transmitters located in the maintenance hangars for testing of similar equipment aboard aircraft in the hangars. The loss of all GPS information doesn’t occur as long as the hangar doors are closed or there is equipment, tooling and aircraft blocking the maintenance signals.
The integrated avionics receiving two different types of signals and shut down. This is a known issue at many MROs, but is very limited and infrequent. It can affect nearly all GPS systems.
If this happens to you and you suspect your GPS system is receiving multiple signals, taxi away from the area in front of the maintenance hangars. Once you’ve cleared the area, the GPS systems should reboot and acquire a good signal. After a couple of minutes to clear all of the CAS messages, you will be ready to fly.