PIO in a FBW jet
Not sure if we all understand the "feel" of the roll/pitch commands in most FBW implementations, and what you see and get when stirring the stick.
The best I can find is the majority of FBW jets command roll rate with yokes or sticks or sidesticks. Not bank angle, but roll rate. Anybody else here with a different experience?
The Viper roll rate could be trimmed, as could the gee command for pitch. Airbus appears to be pure roll rate for lateral stick and the gee command is corrected for pitch with fore/aft stick( and you can't trim for roll rate or gee). The 'bus also stops you at certain bank angles if in the various laws above "direct".
So if you let go of the stick you are gonna get a zero roll rate command for the 'bus and trimmed rate command for the Viper. You may not maintain your bank angle, but the system is giving her all it can. With my leading edge flap failure configuration I could not trim out for roll. But could trim yaw. I had to hold 16 - 17 pounds of left stick until I landed.
So to help roll problems or roll rocking you relax pressure/degrees of stick displacement and then go from there. The computer will try to keep you at the trimmed roll rate - zero for the 'bus. If the bank angle keeps increasing or decreasing, then you have problems with the control surfaces or a truly screwed HAL. The exercise is even easier than with the old conventional controls whether direct from cables or hydraulics.
You only get into trouble trying to deal with unusual roll rates ( and maybe some yaw back and forth). We saw that with the 'bus outta JFK when the tail came off and the KC-135 in one of the 'stans.
I can understand the inertia effects for a big jet like the 'bus or 777 or .... Even if HAL is doing its best, roll may take a second or two or three to stop. I bet it also took a second or two to establish a high roll rate, huh?
enuf of flight control laws and implementations from this old fart...