From Boeing presentation to Congressional Hearing page 16 of 45
Enclosure to RA-19-00256
Page 14 of 43
System Level Functional Hazard Assessment (FHA)
Erroneous Inputs to MCAS Control Law
Erroneous inputs to MCAS control law could result in loss of MCAS function or
unintended MCAS activation.
Unintended MCAS activation due to erroneous input would still be subject to
the control law table limits encoded in the MCAS software (2.5 deg maximum
incremental stabilizer movement)
Unintended MCAS activation has previously been shown to be:
. Major in normal flight envelope.
- Failure can be countered by using elevator alone.
. Stabilizer trim available to off load column forces.
. Stabilizer cutouts available but not required to counter failure.
. Hazardous in the operational fight envelope.
. The probability of being outside the normal flight envelope is 10-3 (refAC 25-7C). Therefore, a condition that meets the integrity requirements for a Major within the normal flight envelope also meets the Hazardous integrity requirements for the operational fight envelope.
The above is/are Boeing FACTS as presented to Congress in a public hearing - the next page has interesting graphics re limits