Originally Posted by
gums
Salute!
- I still look for evidence of a mechanical failure, but looking at the traces..... I see no clear evidence of mechanical failure, although the overheat possibility put forward may be relevant. And then there's previous flight and maybe not enuf lube on the screw as we saw in Alaska crash. I am leaning more and more toward an electronic cause by Hal and his minions. They seem to be able to move the stab without pilot consent.
- Stab is way more powerful than the elevators. Even with full deflection of the elevator, once above a certain "q", the elevator will not be able to overcome full stab deflection.
- No big rate changes on the stab position. Same slope of movement as all previous down cmds.
- At "the event", engine data shows significant power demand for a few seconds. and then one large down command from Hal, and stab moves. Another large down cmd then comes from Hal.
- By now, we see large control forces by both folks and eventually 100 pounds by the pilot. Damn, but this is scary.
Gums posits....
Wouldn't the increase in airspeed and high opposite elevator input fit the Boeing warnings for the 727 and older 737s that you may need to relax elevator input to allow trim in the same direction as your input. The elevator airload overpowers the jackscrew leverage. They might have been pulling and trimming but the stab wasn't moving. I saw this in a 727 simulator a long time ago. Is that warning still in the newer 737 FCOMs?