The EFCTB has been Designed to support all Boeing aircraft with Elevator Feel Computer and Centring Units including all needed gauges/pumps in one single box.
Q : Which main application does the EFCTB support?
A : On Boeing 737, the FEEL DIFF PRESS indication on the flight control panel can illuminate in the following cases: (The feel system simulates “actual feel forces” at the control column from the hydraulically [...]