PPRuNe Forums - View Single Post - Boeing 737 Max Software Fixes Due to Lion Air Crash Delayed
Old 2nd May 2019, 10:45
  #844 (permalink)  
Loose rivets
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FrequentSLF #843

I am not a pilot, but I have eletrical and automation background.
Based on the wirings that are available on the net the systems are as stated.
MCAS is not stopped by column switches!
MCAS cannot be disabled without cutting off manual electrical trim, which means only wheel cranking can be used if CUT OFF switches are used.
CUT OFF switches are connected in series, and renamed PRI and B/U, either one will CUTOFF all electrical controls (manual thumb on control column, autopilot, STS, MCAS), while on NG one switch will cut off automatic trim, while the other whole cut off the electrics.
Well, I found it hard to reconcile the MAX system as described in the AV H's question list - with the outline wiring we'd all been lead to believe was simply a series BackUp configuration. It was too late last night to trace circuits, but 737 Driver did protest it doesn't matter about the details, as long as the crew take the right actions. I have never thought like that and if I'd been on type, (and 40 years younger) I would have known exactly what that circuit did. At least, I hope I would, given I'd got the first clue that something like MCAS was lurking in the background.
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