Originally Posted by billt460
I seem to remember a couple of fatal, (no survivors), 737 accidents that happened with several years in between, similar to this. (I'm sure Astro remembers both, and he can feel free to add or correct anything I may have gotten wrong here). Both ended up being caused by the same thing. One happened in Colorado Springs, and the other 3 or 4 years later in Pennsylvania. They never solved the Colorado Springs crash until after the Pennsylvania crash happened.
If I remember correctly, it was caused by a faulty designed hydraulic valve. That somehow managed to reverse the rudder pedal input. But only sometimes under certain rare conditions. But all 737's continued to fly with that bad valve for several years in between both crashes. Because they never discovered it until after the Pennsylvania crash. (Both were similar accidents, going in near vertically).
I hope this doesn't turn into the same thing. Not being able to solve 2 non survivable crashes involving the same aircraft is scary. (Assuming they were both caused by the same thing). And that it turns out to be mechanical. Now it's just too early to tell.
They didn't ground the 737 after the Colorado Springs crash, because some believed at the time it might have been weather related. (Rolling wind shear off the mountains, or some such occurrence). Not to mention it would have been economically devastating to so many airlines worldwide, and would have made a mess of airline travel. This appears to be shaping up differently. That said, these 2 crashes involving the 737 Max aircraft happened months in between... Not years.
That was unbelievably good work finding that bad valve, and solving the problem once and for all. I hope the same thing happens here... Assuming something in the aircraft is faulty.
You remember correctly, Bill - and the forensic analysis that revealed the design flaw in the rudder actuator is a textbook case of how to conduct an investigation.
I talked about that in this thread:
https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/4592998/all/Boeing_737_Max_take-off
I wasn't kind to the FAA or the 737 in my series of posts in that thread.
I'm clearly not a 737 fan, but I don't blame the 737 for either Lion Air or this crash.
We have, in both these crashes, the intersection of new design, poor communication from manufacturer, poor training by airlines, poor dissemination of updated procedures, and pilots who really don't know how to fly.
The specific crashes to which you refer were US Air 427 and United 585.
They crashed as the result of a design flaw and mechanical malfunction that slammed the rudder to the stop, and left it unresponsive to pilot input. Totally different than what we're talking about with Lion Air, and speculating about with Ethiopian.