View Full Version : 747-400 Rudder Trim System

10th Aug 2019, 06:50

A quick question about the ruder trim system on the 747-400/-8. With hydraulics depressurized, does the rudder move if the trim is actuated?

I am going to say no, that the rudder trim uses an electric motor to reset the neutral position of the rudder pedals and that no control surface movement occurs until at least one hydraulic system is pressurized, but I am not sure.

Does the aileron trim function in a similar way (electric motor to reset yoke's neutral position)?

Thank you.

10th Aug 2019, 21:44
You’re correct. The switch control adjusts the trim and feel mechanism neutral positions.

11th Aug 2019, 19:20
Thank you!