PPRuNe Forums - View Single Post - AF 447 Thread No. 12
View Single Post
Old 21st Aug 2014, 22:37
  #287 (permalink)  
RetiredF4
 
Join Date: Jun 2009
Location: Germany
Age: 71
Posts: 776
Received 3 Likes on 1 Post
Come on Dozy,
you can do better than that.

From FCOM A 330/340

In certain failure cases, such as the loss of VS1g computation or the loss of two ADRs, the longitudinal static stability cannot be restored at low speed. In the case of a loss of three ADRs, it cannot be restored at high speed.
AF447 Final report:
The flight control law changed from normal to alternate at about 2 h 10 min 05. The alternate law was 2B and it did not change again thereafter. Due to the rejection of the three ADR by the flight control computers (PRIM), the abnormal attitudes law could only have been triggered for criteria relating to inertial parameters, but these conditions were never met.
There was no low speed stability function available in Alt 2b. A neutral stick would not have led to a reduction in trim. With the kind of tripple ADR failure Direct Law should have latched and thus disabling autotrim, but this did not happen as all three ADR's were rejected simultaneously.
But i'm not going to go through this again after all these years.
RetiredF4 is offline