Lonewolf50 said :
[...] it appears that PRIM 2 had already failed before it was called upon to act as the back up [...]
Unfortunately, PRIM2 did not fail, else we would have a PRIM2 FAULT somewhere, which we don't. This is a silent "failure".
which perhaps provided the two gents on the flight deck the dubious honor of becoming test pilots ... without a test plan, with a load of pax, and with no briefing for the data points to be collected.
Thank you, Lonewolf...