[twtw]

But they neglected maintenance when serious issues with the plane were apparent. The pilots of the flights prior to 610 noted that the two AoA sensor readings differed by ~20 degrees, and nearly aborted their flight before overriding the auto trim.

Flight 610 should never have taken off.

[Someone1234]

That's a misstatement of what occurred. The aircraft had a fault on the previous two flights and was repaired before the fatal flight.

> Flight 610 should never have taken off.

A repaired aircraft should not take off?

[twtw]

The preliminary report from the investigation of LNI610 disagrees with you: https://reports.aviation-safety.net/2018/20181029-0_B38M_PK-...

The AoA attack sensor was replaced prior to flight LNI043 (he flight prior to 610), in which the pilots declared pan-pan and had to manually override the auto trim systems (which include MCAS). Between 043 and 610, there was further maintenance that included flushing the pilot valves and cleaning electrical connectors, but the AoA sensor was not replaced between 043 and 610.

An aircraft that was repaired followed by one flight in which the pilots declared abnormal operation and performed 3 non-normal checklists should probably not fly again until they figured out what happened, and the next flight should definitely be aware of the incident on the flight prior. 043 faced and overcame the exact same malfunction as 610 - to me that indicates a clear failure. If you keep flying an aircraft that malfunctions on each flight, you're pressing your luck.

[Someone1234]

> Between 043 and 610, there was further maintenance that included flushing the pilot valves and cleaning electrical connectors, but the AoA sensor was not replaced between 043 and 610.

They followed Boeing's procedure in attempting to address the issue again (after already replacing the sensor). That's a completely appropriate action.

> the next flight should definitely be aware of the incident on the flight prior.

It is in the log book. Is this a reference to something particular?

> 043 faced and overcame the exact same malfunction as 610 - to me that indicates a clear failure.

I agree, that's why maintenance conducted a repair.

> If you keep flying an aircraft that malfunctions on each flight, you're pressing your luck.

They attempted two repairs in accordance to the manufacturer's procedures within that time in order to resolve the malfunctions.

This post references the report and you clearly read it enough to know your original conclusion was mistaken, but are still arguing you're right by trying to shift the discussion. You've gone from "they flew a broken aircraft" to "alight, so they repaired it twice, but you cannot ever trust a malfunctioning aircraft again." By that logic every single commercial aircraft would be in the junkyard... Repairing malfunctioning systems is normal, attempting two different repairs isn't uncommon either.

[salawat]

It's not fixed until it is fixed.

I understand that with physical systems, the cost and complexity of detecting is higher, but if you're putting other people on the line, you damn well better do a live test of your vehicle before another living soul not certified as a pilot or flight engineer is allowed on board.

The more I read about this, the more it appears to me that excessive trust is placed on filed paperwork. Nothing says a fix is done like a successful test flight that specifically attempts to recreate the conditions surrounding the original failure.

[twtw]

> You've gone from "they flew a broken aircraft" to "alight, so they repaired it twice, but you cannot ever trust a malfunctioning aircraft again."

If you think I've changed my argument, you misunderstood my comments. I still think that they flew a broken aircraft.

I'll stand by my statement that 610 should never have taken off, and I'm somewhat surprised that it is contentious. I don't care if all the protocols were followed and the logs made (though obviously the pilots of 610 didn't understand what the previous pilots had done to respond to their incident) - in retrospect, we know that the aircraft was not airworthy going into flight 610, so something needs to change so that next time that is detected before takeoff. Whether that is better observation of the protocols or better protocols, I'm not sure.

[salawat]

Does repaired in this context also include a successful in-flight test?

At some point, the complexity of system integrations requires that you do something more than bare minimum component retesting.