Hi Franz,
Originally Posted by RetiredF4
Automatic trim is frozen in the following cases
- load factor lower than 0,5gs
Would that not inhibit the trim to move ND when unloading enough (provided elevator authority is big enough)?
Yes, it will be limited to the duration of threshold excess, when load factor will be lower than 0.5gs, IF, at any time, they applied that much ND, which doesn't seem to be the case either.
Originally Posted by RetiredF4
"When angle of attack protection is active"
Shouldn´t that have prevented or hindered the THS to move to 13°ANU?
Im familiar, that the described paragraphs relates to normal law. Are those vital features lost in ALT LAW?
Yes they are lost. This protection, like any other active protection, was lost from the start of the event when EFCS is directly set in Alt 2.
UAS is very nasty, only g-load protection (which is passive) will remain and protect the airframe from g-load exceedances.
Originally Posted by RetiredF4
could this mode ["Low speed stability"] have been activated on behalf of the wrong IAS?...And what is meant by the term "bank angle compensation is provided"?
No, same as above, it doesn't work with UAS in Alt 2. There was no more "Stall_Speed" to refer to for the system to make it working.
"Bank angle compensation", should mean that the system will try to bring back the wings level or prevent any increase of bank angle while reducing NU attitude.
Originally Posted by RetiredF4
I still dont get the whole picture of those law changes and the asociated protection changes or protections lost.
It's not easy to grasp it at the first reading.
When going to Alternate law mode, the five active Normal law protections are lost. But, depending on the kind of fault causing Alternate law switch, two protections may be replaced by Alternate ones (Low Speed and High Speed).
In our AF447 case, with a triple ADR fault, those protections are lost as well, and it seems very bad as they could have prevented this crash.