when was 747 bump removed

[lynn789]

early 747s were notorious for bumping around at the back, experienced pax avoided sats down there
was diehederal added to tailwings or tailfin altered?
I think the connection between autopilot and yaw damper was the eventual fix, but when?

[Wizofoz]

No expert on the type but I suspect it would have been with the introduction of the -400

[Fitter2]

I have it on good authority that if you think the standard early 747 was 'jumpy' at the back, you should try a ride in the NASA sShuttle transport. The wingtip vortices from the Shuttle lined up perfectly with the extra fin area added for directional stability; down the back you could see the whole fuselage twisting. 'Comments' were made, fatigue calculations done, and the answer was 'we're not doing a redesign now, put up with it'.

[NSEU]

I think the connection between autopilot and yaw damper was the eventual fix, but when?

There is no connection between the autopilot and the yaw damper on the 747-400.

They are completely independent.

The Yaw Damper System uses inputs from the Inertial Reference Units (IRUs) and Air Data Computers (ADCs) and 4 dedicated accelerometers (positioned at the front and rear of the fuselage).

The IRUs and ADCs send data to Yaw Damper Modules (computers). The Yaw Damper Modules, using this data, compute and then output signals to the rudder actuators for coordinated turns and general yaw damping.

The dedicated ("modal") accelerometers sense fuselage twisting and the Yaw Damper Modules use this information to compute and send minor corrections to the rudder actuators to try to dampen the twisting.

Rgds
NSEU