Emergency Electrical Power

Question 1

How is the Emergency Generator powered? When does the RAT come out? If the RAT doesn’t automatically come out during the loss of AC bus 1 & 2, how is it manually deployed? Which hydraulic does the RAT use?

Answer 1

1. The Emergency Generator is driven by the RAT (Ram Air Turbine).
2. The RAT automatically comes out when both AC BUS 1 and 2 are lost 3. The RAT is released manually via the EMER ELEC PWR, guarded Man On pb
3. The RAT uses the Blue hydraulic system

Question 2

3 Speeds to remember for the RAT? How long after the RAT is deployed before the Emergency Generator comes on line?

Answer 2

1. *Above 140 - the Rat powers the Blue hydraulic system which drives the Emergency Generator
2. *Below 100kts but above 50kts - DC BAT BUS is connected to the batteries
3. Below 50kts - AC ESS BUS is shed, loss of all display units

*Rat deploys with AC Bus 1 & 2 fail and speed is greater than 100 kts. It takes 8 seconds to deploy and activate the Emergency Generator