Static ports on the vertical stabilizer?

[extricate]

Hi,

Any idea what's the purpose of having static ports on the vertical stabilizer for B777?

Did some search and found it has something to do with rudder ratio limiter? Have not heard of it before.

Can anyone advise?

[IFixPlanes]

These static ports are called "gust suppression pressure transducers".
They measure the pressure difference between both sides of the vertical stabilizer and this helps to improve the quality of passenger ride in the aft portion of the fuselage during wind gusts.

[extricate]

I see, thanks!

[Running Ridges]

Interesting... How does it improve comfort? Automated rudder inputs to counter it?

[Vessbot]

Sounds like it, and with a quicker response to the aero pressures than to the lateral accelerations that are the result of those aero pressures, and which are acted on by traditional yaw dampers.

[tdracer]

Originally Posted by IFixPlanes

These static ports are called "gust suppression pressure transducers".
They measure the pressure difference between both sides of the vertical stabilizer and this helps to improve the quality of passenger ride in the aft portion of the fuselage during wind gusts.

Is this something relatively new? I worked the 777 for a while (although not since 2002) and I don't recall hearing about the system.

[vapilot2004]

Originally Posted by Running Ridges

Interesting... How does it improve comfort? Automated rudder inputs to counter it?

Exactly.

The ports sense pressure changes between the right and left sides of the vertical stabilizer. This information is read and transferred to the actuator control boxes, which command rudder movements to counteract the effects of wind gusts on the tail of the aircraft.

Is this something relatively new? I worked the 777 for a while (although not since 2002) and I don't recall hearing about the system.

As far as I know, there is no control switch and the only way one might be aware of the system is through some maintenance pages on the CDU, or, of course, the presence of the static ports and transducers in the vertical stabilizer. It is but one small part of the stability augmentation system of the flight control computer system.

[sleeve of wizard]

From the AMM

[underfire]

That system is the flutter in the tail that everyone, especially the crew, complains about....

[Basil]

Interesting; wonder if that can be used to limit the fin root bending moment?

[IFixPlanes]

We do NOT talk about Yaw Damping!