Ethiopian airliner down in Africa

[infrequentflyer789]

Originally Posted by safetypee

I may be dancing around the same tree as in my post in the other thread - #485 Boeing 737 Max Software Fixes Due to Lion Air Crash Delayed
Where is the value of AoA sampled by the FDR; would this clarify current understanding.

737 NG AMM says that the FDAU (flight data acquisition) gets AOA from the SMYD (stall management and yaw damper) and that analogue resolver outputs go to both SMYD and ADIRU (the latter feeds FCC).

Peter Leeme has previously suggested that MAX no longer has separate SMYD "box" - however he retracted that a couple of days ago in this post:

In prior posts I have postulated whether SMYD had become a function in the FCC on the MAX. I was wrong. The SMYD appears on the 737 MAX pretty much as the 737 NG. This is a significant realization. The AoA vane has one analog resolver output connected to the ADIRU, and one output connected to SMYD.

I would suggest that the most likely source for FDR AOA value is the SMYD, as on the NG.