HN39
Were these the statements from the interim QF72 report that gave a minus 4 degree alpha protect control authority?
Flight envelope mechanisms
• First upset was close to worst possible
scenario:
– 4 degrees alpha prot, 6 degrees anti pitch-up
• AOA processing algorithm using just two
sensors only on A330 and A340
– different algorithms used on other Airbus
aircraft
If Alpha protect authority is limited, the authority may vary based on CAS.
At lower speeds, more authority would be needed. If the aircraft was actually slower than the flight control system recognized, then it might be possible to have inadequate Alpha protect authority=prompt stall entry on a Vmo/Mmo protect pitchup.
I haven't had much luck finding more information on any Alpha protect authority design logic. I might also be mis-interpreting the meaning of the QF-72 report.
However, that was a very astute call of yours pointing to an authority limitation.
