Originally Posted by
Deepinsider
Thank goodness. A jury of twelve normal people willing to apply common sense and fairness.
The wisdom of a crowd.
Willow Run raises a lot of good points, and this is not going to look good on the resume of the corporate dear leaders of the manufacturer, but I still await someone to start the litigation on the inherently oddly flawed manual trim situation of the B737 which doesn't appear to meet the requirements of Part 25 and seems to be at odds of the intent of the requirements. being able to control the aircraft at all foreseeable times seems to be a good idea.
A failure of the primary trim control is a foreseeable condition and leads to the manual trim wheels still gracing the geriatric pedestal of the B737. Yet, where the initial out of trim condition requires the use of manual trim, there are conditions where it will not be possible without unloading the elevators which is only viable if there is enough air below you.
ET-302 was set in motion by MCAS, but that was all, it ended up on the ground in a heap from the fact that reportedly following the manufacturer's procedure post Lion Airs event couldn't be recovered, and the most likely reason for that is the manual trim was overpowered by the need for nose-up elevator.
That leaves the question as to how safe is an aircraft that can be recovered only if you don't mind letting go of the elevator deflection while in an extreme flight attitude with the world rising up rapidly. The certification isn't supposed to have a caveat, "except if you are having a bad day..." pretty sure that Subpart B, ^25.143 doesn't say that, in fact, 25.143(b) seems to suggest that
"It must be possible to make a smooth transition from one flight condition to any other flight condition without exceptional piloting skill, alertness, or strength, and without danger of exceeding the airplane limit-load factor under any probable operating conditions..."
That doesn't gell with having to do a rollercoaster at 400kts and 3000'AGL because the stabilizer manual trim actuating torque exceeds the pilot's strength where the elevators are being used for trivial matters such as keeping your nose from burying in the turf.
Separately the trim requirements a bit later hint that trim is important... but also seem to be myopic, and letting a design that may be inherently nasty to be certified. The AOM that was put out to disclose the MCAS system actually existing, and what the manufacturer suggests was a good response also indicated in wording fit for a lawyer as far as being obtuse, knowing that 80% or more of the operators of the plane have English (UK or US variant) as a second language, but still it intimated that the manual trim system sucked, as ET-302 found out.
Lots of these designs floating about, and who is asking the question of how much the inherent weakness of the manual trim contributed to the loss of Ethiopian. That is a question for a sharp lawyer and is also the way in to get some dignity for those impacted by the disgraceful behavior of the feds with giving Boeing a slap over the wrists and a cookie and some fresh milk. So much for the honor, integrity, and independence of the US DOJ.
In my humble opinion. But before discounting this view, read the AOM that was put out to ET, and all other operators by the manufacturer, note the bit about trim and note that the wreckage reported the stab trims in cutout.
Join the dots, respect those that died needlessly, and fix the manual trim system.
I'm not bashing the manufacturer, they were once the pinnacle of conservative while innovative design, and something is missing in their DNA now, seems to have occurred around 1995 or so... curious. I wish for a return to excellence in design (with occasional whoopsies... JAL103 APB repair oops) that made driving their designs a pleasure.