Before revision: For example, on larger aircraft such as the Boeing 747-400, the avionics bays are divided into 3 parts - the main equipment center (MEC), the center equipment center (CEC) and the aft equipment center (AEC).
After revision: Avionics bay of a passenger aircraftFor example, on larger aircraft such as the Boeing 747-400, the avionics bays are divided into 3 parts - the main equipment center (MEC), the center equipment center (CEC) and the aft equipment center (AEC).