Originally Posted by
Derfred
He did say one strange thing though: if it is correct in translation, he asked the F/O "to trim up with him". This was after the second MCAS. He had only responded to the first MCAS with a relatively short "blip" (2.1 to 2.4 units). The response to the second MCAS (presumably with the F/O "helping") was around 11 seconds and took it from 0.4 to 2.3 units (if only they'd kept going another 11 seconds).
So why did he need the F/O's help to activate main electric trim? It's a thumb switch. Was the stick-shaker that annoying he couldn't activate the thumb switch? Could this mystery have anything to do with the two fatally short "blips" near the end of the flight?
If I turn a thunb switch which should turn a wheel and nothing happens, I release it before I cause further damage. Then I ask another person with another thumb switch if the other one is working... This is the only straight-forward strategy, the last straw...
I already raised the questions if the short blips are short because nothing happened. This woult be in line with the CVR. And maybe the Lion Air PF handed over control because he lost control of the el. trim?
So maybe either:
-> the motor overheatet after x cycles / went into thermal protection
-> Aerodynamic forces blocked the motor
-> The jackscrew got damaged (blocking ANU completely)
Both flights showed such blips before things went wrong completely. Such things will probably never show up in the simulator and you presumably won't try them out on test flights either...
Second mystery: Why were 3 AoA sensors damaged or 'misinterpreted' within 5 months? And why are there so many similarities in both maintainence logs? Is this the second bug they found? Data acquisition?