Originally Posted by
sleeve of wizard
Sounds like you have a handle on things.
But don't take my word for it, a lot of good information can be found in the FCOM, give it a go next time.
This time I've done the work for you, "the flaps and slats can operate independently in either primary or secondary mode. However, independent flap and slat operation in the alternate mode is not possible."
Remember, when the operation is in secondary mode, it is a much slower movement. If one item operates slowly(electrically) while the others operate hydraulically(primary) you will get an asymmetry. Which of course will stop everything in secondary as there is still protection for this.
As stated in the book, " In secondary mode, flaps and slats are positioned by electric motors."
When the FCOM talks about flaps and slats operating independently, they are not talking about an individual flap or slat operating independently from their sister slats or flaps. They are talking about the slats operating independently from the flaps and vice versa. For example, in primary, when flaps 1 is selected, only the slats move(independent operation). As well, with flaps extended to 1 or greater in normal mode, autoslats operation happens at an approach to stall(they go from mid position to fully extended independent of the flaps. Flap load relief can happen in primary mode while slat load relief can happen in secondary mode. All independent movements from each other.
As stated earlier, there is no independent movement in Alternate.