EMB ERJ 170/175 ER/LR
Flight Crew Air Transport Pilot (ATP)
Confusion
Aircraft Equipment Problem Less Severe
Flight Crew Landed in Emergency Condition; Flight Crew Returned To Departure Airport; Flight Crew Returned To Gate; General Maintenance Action
Aircraft
Went through Immigration and conducted an aircraft swap. New Swapped aircraft experienced maintenance issues from power-up which included No Dispatch and front landing gear door opened. Maintenance was called and all was resolved. Pushed back for the second leg; only to be presented with Erroneous EICAS messages which included the following : FLT CTRL NO DIS PATCH; A/T FAIL; AP FAIL; AVNX Modular Avionics Unit (MAU) 3A FAIL; NO DISPATCH; ADS 3 FAIL; SPOILER FAULT; APM FAULT; F/D FAIL FMS 2 FAIL; STALL PROT FAULT; AUTO CONFIG TRIM FAIL; YD FAULT. These messages were presented about 5 times of which were during the start of engine 1 and engine 2; and the shutdown of the APU; and 2 subsequent times. This messages led to a return to gate and a subsequent delay. During this time Line Maintenance was called to the aircraft and an engine run-up was performed. The aircraft was signed off and returned to service. Pushed from the gate and taxied a second time to the runway. On the Takeoff roll after the VR call EICAS messages presented themselves once more along with a master caution. These messages included the following: AVNX MAU 3B FAIL; A/T FAIL; AVNX MAU 3A FAIL; ADS 3 FAIL; SPOILER FAULT; DATALINK 1 FAIL; ENG TLA TRIM FAIL ADS 4 SLIPCOMP FAIL; FMS 2 FAIL AND AUTO CONFIG TRIM FAIL. At the captain's request we advised ATC and proceeded back to the field. After landing; all the previously stated EICAS messages were still all present with the addition of ENG 1 AND 2 NO DISPATCH; LG NO DISPATCH AND FLT CTRL NO DISPATCH and 2 circuit breakers on the MAU 3 had been tripped. After arrival at the gate; we contacted line maintenance once more; and we were advised that the aircraft was grounded.
EMB-175 First Officer reported a Modular Avionics Unit 3A and 3B failure causing numerous false EICAS messages. Flight returned to the departure airport.