A trimmable horizontal stabilizer is a key feature in many airliners and transport aircraft. This component, similar to a stabilator, includes a fully moving horizontal tail surface. However, there’s a crucial difference: the trimmable stabilizer doesn’t move based on the control column or stick. Instead, it uses elevators that respond to inputs from the pilot or autopilot to manage pitch. The entire horizontal tail assembly adjusts via the trim system, helping to stabilize the aircraft along the pitch axis.
One of the main benefits of a trimmable stabilizer is its ability to provide significant trimming power across the aircraft’s full speed range. This system also helps reduce drag since the stabilizer and elevator align whenever the aircraft is trimmed properly. Typically, the stabilizer trim is adjusted before takeoff to account for the center of gravity position, ensuring the elevator works effectively.
Most trimmable stabilizers are controlled manually or electrically and are actuated hydraulically. In advanced Fly-By-Wire equipped aircraft, the stabilizer can even adjust automatically to a one G loading without any input from the pilot.
