I went back and looked at the report. The CAB said the autopilot was tagged inoperative pending a required modification. This suggests that the parts may all have been there and functional, but there's no indication what exactly the crew would have known. The report did mention that the autopilot switch was accessible.
My comment about wondering if the crew thought they were fighting an autopilot that had activated uncommanded comes from recollections of what we discussed at the time. We had a lot of conversations with NWA pilots and some contact with investigators, which is why the ALPA report is a carbon we were given. The CAB report doesn't directly address that.
The CAB report said spark damage indicates there was power in the autopilot, but they couldn't rule out something happening in the impact sequence.
The CAB also said the boost units were in the engaged position for the elevator and rudder, and disengaged for the ailerons. This is the ideal configuration, but they also said they didn't rule out that the impact forces acted to engage or disengage something that was set the other way during the flight.
This whole incident has really started to flesh out for me now. My next document version is going to have a section covering these systems and how they're intended to (and perhaps did) interact.
Last edited by BRDuBois; 21st Oct 2016 at 17:18.