EMB ERJ 145 ER/LR
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical
Flight Crew Returned To Departure Airport; Flight Crew Landed As Precaution; General Maintenance Action
Aircraft
While climbing out the departure the EICAS displayed L/G Air Ground Fail message an aural warnings that seemed to indicate that aircraft's logic was indicating the aircraft on ground instead of in the air. We completed the after takeoff items and informed ATC that we will need some delay vectors. I (First Officer) pulled out the QRH and located the page related to that EICAS message. Meanwhile the Captain asked ATC to level off at 6;000 and we switched the controls. We performed the required QRH items and Captain contacted Operations and informed them of the gate return. Captain informed the ATC about an air return and we set up for an ILS approach. After landing when the speed went below 10 KTS we got a stick shaker and other SPS messages associated with it. While at the gate when Captain switched to GPU power more system stopped working such as SAT; TAT; Fuel quantity etc.; indications stopped working. The list of messages on EICAS exceeded one page. The gust lock did not lock the elevator; so we secured with a seat belt and left the aircraft with Maintenance personnel.
EMB145 First Officer reports the EICAS displayed L/G Air Ground Fail message during initial climb. After complying with QRH procedures crew elects to return to the departure airport. Many anomalous EICAS messages and stick shaker activation are reported during taxi in and shut down at the gate.