How Flight Controls Work | Part 1 : Horizontal Stabilizer

Summary

Key Points

• The Boeing 777 was the first Boeing aircraft to incorporate a fly-by-wire system, enhancing performance and safety while ensuring pilot authority. 0:01
• The horizontal stabilizer is a critical control surface used to trim the aircraft's pitch, with its operation varying between ground and flight. 0:25
• At the core of the aircraft's flight control system are three Primary Flight Computers (PFCs) that process all control surface commands from pilots or the autopilot. 0:43
• Four Actuator Control Electronics (ACE) assist the PFCs by converting analog signals to digital and vice versa, ensuring redundancy and accuracy. 0:53
• When on the ground, stabilizer trim switches on the control columns send electrical signals to the ACE, which then transmits them to the PFC. 1:06
• The PFC calculates the stabilizer's movement speed, allowing maximum speed on the ground, and sends the final signal back to the ACE. 1:36
• The ACE converts the digital signal to analog and sends it to two stabilizer trim control modules, which use hydraulic power to operate the stabilizer actuator. 1:41
• Hydraulic motors, powered by the trim modules, turn a ball screw connected to the stabilizer, causing its leading edge to move and adjust the aircraft's pitch. 2:23
• Stabilizer position is indicated in the cockpit via position transducers, and releasing the trim switch directs the module to stop movement and re-engage hydraulic brakes. 2:29
• An alternate pitch trim lever provides manual control, mechanically connected to the trim modules to operate the stabilizer independently of the electrical system. 2:55