View Full Version : NG Speed Trim System
Pin Head
11th Feb 2016, 07:03
Hi
Am I right in thinking that the system will in a high nose attitude increasing speed situation try to trim up even further to control and stabilise speed?
Many thanks
Pin
Jwscud
11th Feb 2016, 09:05
Yes. I have seen just this behaviour recently with high positive wind shears between the surface and 1000ft lately. If you hold a constant attitude with speed running away from the trimmed speed it will "help" you. Obviously the easiest solution is to trim the other way as that both helps you out and inhibits the system up to 5s after you let go of the trim switches.
It is working to design, just like the FD suggesting one pitches to 25° to keep speed then rocket back down to 10° the moment the wind entirely predictably steadies :ugh:
de facto
11th Feb 2016, 16:04
jesus...ask your fos ...they ll know.:E
aaa0808
12th Feb 2016, 05:25
No, it will not. The speed trim system fixes the stick-force/g so as to bring it above a minimum value. So in high lift conditions, it will increase the stick-force/g so that the pilot has to pull more aft column to stall the airplane. The stabiliser is trimmed nose down in this situation by the speed trim system.