Re #1791, - Realbabilu
Lion Air have a valid point. If all necessary rectification actions had been taken, and systems checked, then there is no way to identify an ‘unairworthy’ aircraft.
Operators do not ground aircraft every time that they encounter ‘ground tested, no fault found’.
Although there was a history with this aircraft, it is reported that there were intervening flights without problems - only the last two faults were consecutive, (if so why - faulty system resetting / intermittent), and not the exactly the same symptoms being reported after each flight (but probably the same insidious fault), then the operator had reasonably exhausted all ground work.
The debatable point is whether to air test vs ‘check next flight and report’; again compare this with industry practice for intermittent fault finding; EFIS display and stick shake, associated with a recorded AoA fault log, and less than compelling evidence of a trim problem; all of which had been addressed by maintenance action, probably justifies ‘check next flight’, irrespective of an onboard engineer - would he have twigged the significance of trim. Also after one flight a pilot erroneously related the AoA / air data problems with STS, ‘they accounted for the trim going backwards’.
In fact there was no trim problem, it worked as designed; it’s just that this design was not communicated to pilots (would there have been a checklist for failures at this time - before the accident), it would be impossible to describe the exact nature of issue to maintenance. Thus without a description, nor understanding of the likely severity of the malfunction, neither pilots or maintenance could be expected to do better; no better that the regulatory authorities or even Boeing in recognising the hazard.