PSA Airlines Canadair Regional Jet Systems (PSA-CRJ) Practice Exam

What limits the functionality of the EICAS on the ground with battery power?

1. Insufficient battery voltage

2. AC powered cooling fans are not operational

3. The EICAS system is designed for temporary use

4. Incompatible input signals

The correct answer is: AC powered cooling fans are not operational

The EICAS (Engine Indication and Crew Alerting System) functionality on the ground is limited primarily due to the inoperability of AC powered cooling fans. These fans are essential because they help regulate the temperature of the system. When the aircraft is on the ground operating solely on battery power, these cooling fans cannot function, which may lead to overheating of the EICAS components. Consequently, to ensure the system remains functional and protected, its operational capacity is reduced when only battery power is available. The other factors, while they may influence system performance, do not limit EICAS functionality in the same critical way when battery power is the sole source. Insufficient battery voltage might lead to complete system failure, but it does not specifically limit EICAS to a temporary mode. Temporary use is more of a design limitation rather than a direct cause of reduced functionality due to environmental controls. Lastly, incompatible input signals are less of a factor in this context, as they typically pertain to the data received from aircraft systems rather than the immediate conditions of power supply and operational cooling.