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PostPosted: March 18 19, 11:51 am 
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Quote:
The Times also noted that elements of the safety review were handed off to Boeing to complete, rather than the Federal Aviation Administration, which has issues with funding and “has over the years delegated increasing authority to Boeing to take on more of the work of certifying the safety of its own airplanes.”

the referenced article, not sure if posted already
https://www.seattletimes.com/business/boeing-aerospace/failed-certification-faa-missed-safety-issues-in-the-737-max-system-implicated-in-the-lion-air-crash/

Backtracking to prior comment I made. Not denying that whichever party in charge had been dumped loads of cash upon it by Boeing and vice versa with govt contracts, tax cuts and oversight changes.


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PostPosted: March 18 19, 12:10 pm 
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That article covers the engineering as well as regulatory aspects well and is extremely damning imo. Seems clear that safety review was considered an annoying beuaracratic nusicance getting in the way of the more important priority of production schedule. A familiar scenario most engineers will recognize, I imagine.

Also, the failure to take obvious fail safe measures looks pretty inexcusable to me as basic engineering. Congress should demand accountability.


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PostPosted: March 18 19, 12:18 pm 
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This is huge WTF to me:

On Monday, before the grounding of the 737 MAX, Boeing outlined “a flight control software enhancement for the 737 MAX,” that it’s been developing since soon after the Lion Air crash.

According to a detailed FAA briefing to legislators, Boeing will change the MCAS software to give the system input from both angle-of-attack sensors.


The system is dependent of a single sensor even though there are actually two. Reading this, I initially assumed there must be some hardware reason, the hardware isolates the second sensor for other uses, or something. But they can fix this with a software update? They had access to a second sensor and just didn’t bother to write code to do any consistency check? Mind blowing.


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PostPosted: March 18 19, 1:08 pm 
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I was under the impression, maybe incorrectly, that they have duplicate systems; one for each control panel (pilot and co-pilot). And the panel from whomever is flying at the time dictates which sensors are used for the input. I also think, at least on the Lion Air 737, that there is an option to get a warning light in the cockpit that would alarm if the sensors disagreed however it was not purchased.

Regardless, yes, you would think that there would be some sort of check in the code that would prevent trimming down if both sensors don't agree it is warranted.


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PostPosted: March 18 19, 2:31 pm 
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Also, reading through that article, I found this to be a pretty big screw up.

Quote:

One current FAA safety engineer said that every time the pilots on the Lion Air flight reset the switches on their control columns to pull the nose back up, MCAS would have kicked in again and “allowed new increments of 2.5 degrees.”

...

Peter Lemme, a former Boeing flight controls engineer who is now an avionics and satellite-communications consultant, said that because MCAS reset each time it was used, “it effectively has unlimited authority.”

Swiveling the horizontal tail, which is technically called the stabilizer, to the end stop gives the airplane’s nose the maximum possible push downward.

“It had full authority to move the stabilizer the full amount,” Lemme said. “There was no need for that. Nobody should have agreed to giving it unlimited authority.”


So, Boeing in it's report stated that MCAS would be able to effectively move the horizontal tail only 0.6 degrees, then changed that 2.5 degrees without updating the report. More importantly imo is the fact that it can do that EVERY TIME the MCAS switches on. So, it can move it more than than they originally reported but it resets quickly and can move it the maximum amount multiple times in succession. I think it did it 21 times on the Lion Air flight.

To your point of it being based on a single sensor, the article also makes it sound like it should have been based on two sensors according to their own determination that a failure would result in a hazardous condition.
Quote:
Assessed a failure of the system as one level below “catastrophic.” But even that “hazardous” danger level should have precluded activation of the system based on input from a single sensor — and yet that’s how it was designed.


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PostPosted: March 18 19, 2:43 pm 
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Good thread:



which explains why they did it this dumb way:



Also, sounds like it not true that getting data from two sensors is a software update. Sounds like the second sensor is optional (it should not have been) and the option package gives a warning light but doesn't actually change the basic MCAS operation on a single sensor:



Edit: Though this last point is confusing as Lion Air apparently had two AoA sensors but did not have the AOA DISAGREE warning light per Reuters.


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PostPosted: March 20 19, 7:51 pm 
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AWvsCBsteeeerike3 wrote:
Another issue that I've not noticed any of the media outlets reporting on is the Amazon Air crash which was a 767 and iirc didn't have the mcas system. But, at 6k feet or so, the plane pitched violently nose down and obviously killed everyone.

This theory seems plausible, though I would think experienced pilots would know to trust their instruments over their senses. Curious what's on the voice recording.

http://nymag.com/intelligencer/2019/03/atlas-air-the-boeing-crash-no-one-is-talking-about.html

In online pilot discussion forums, a third idea has been gaining adherents: that the pilots succumbed to a phenomenon called somatogravic illusion, in which lateral acceleration due to engine thrust creates the sensation that one is tipping backward in one’s seat. The effect is particularly strong when a plane is lightly loaded, as it would be at the end of a long flight when the fuel tanks are mostly empty, and in conditions of poor visibility, as Atlas Air 3591 was as it worked its way through bands of bad weather.

The idea is that perhaps one of the pilots accidentally or in response to wind shear set the engines to full power, and then believed that the plane had become dangerously nose-high and so pushed forward on the controls. This would cause a low-g sensation that might have been so disorienting that by the time the plane came barreling out of the bottom of the clouds there wasn’t enough time to pull out of the dive.


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PostPosted: March 21 19, 7:21 am 
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I find it, quite frankly, amazing that this sensation was discovered, more or less, and given a name.

That said, it's a known thing so you'd think pilots would be aware of it AND as you note, you'd think they'd trust their instruments when flying in low visibility. But, who knows.


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PostPosted: March 28 19, 6:37 am 
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Looks like the FAA is making some changes and the Senate is going to be pushing for them to eliminate the self-certification process that they've been using for years.

https://thepointsguy.com/news/the-faa-w ... x-crashes/

Quote:
In a hearing with a Senate subcommittee Wednesday, Federal Aviation Administration officials said they would change the regulatory body’s aircraft oversight procedures following two deadly crashes of Boeing’s 737 MAX 8.

The two crashes, one on Lion Air and one on Ethiopian Airlines, happened about five months apart and had striking similarities. Following the fatal accidents, aviation oversight organizations around the world grounded the 737 MAX until further investigations could take place; the FAA was the last to do so. The crashes, in which a software system designed to prevent stalls but possibly confusing the pilots may have played a part, sparked suspicions that the FAA was too lax in its certification of Boeing’s latest short-haul plane.

For years, the FAA has allowed plane manufacturers to self-certify parts of the oversight process for new planes, called Organization Designation Authorization. This process, in which the aircraft manufacturer’s employees perform some of the safety tests and inspections with FAA oversight, reportedly saved the government body time and money.

That practice was examined at Wednesday’s Senate hearing.

Department of Transportation Inspector General Calvin Scovel III, who testified at the hearing, said the FAA will significantly change the oversight process for new aircraft by July. Speaking in vague terms, Scovel said that the changes would include new ways for the FAA to evaluate the self-certifying process.

Sen. Richard Blumenthal said that putting manufacturers in charge of their own safety audits was like putting “the fox in charge of the henhouse.” Saying he would introduce regulations to ban the practice of companies self-certifying, Blumenthal stated that “the fact is that the FAA decided to do safety on the cheap, which is neither safe nor cheap.”

Daniel Elwell, acting administrator of the FAA, said that using the plane manufacturers’ own employees to self-certify the planes has been “part of the fabric of what we have used to become as safe as we are today.” He noted that the FAA would need 10,000 more employees and $1.8 billion in additional funding to have FAA employees do all the labor of the self-certifying process.

In addition to the Senate hearing and the DOT IG’s probe, the Department of Justice is examining whether to bring criminal charges in the matter of the MAX 8 approval procedures.


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PostPosted: March 28 19, 6:43 am 
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Swirls wrote:
Looks like the FAA is making some changes and the Senate is going to be pushing for them to eliminate the self-certification process that they've been using for years.

https://thepointsguy.com/news/the-faa-w ... x-crashes/

Quote:
In a hearing with a Senate subcommittee Wednesday, Federal Aviation Administration officials said they would change the regulatory body’s aircraft oversight procedures following two deadly crashes of Boeing’s 737 MAX 8.

The two crashes, one on Lion Air and one on Ethiopian Airlines, happened about five months apart and had striking similarities. Following the fatal accidents, aviation oversight organizations around the world grounded the 737 MAX until further investigations could take place; the FAA was the last to do so. The crashes, in which a software system designed to prevent stalls but possibly confusing the pilots may have played a part, sparked suspicions that the FAA was too lax in its certification of Boeing’s latest short-haul plane.

For years, the FAA has allowed plane manufacturers to self-certify parts of the oversight process for new planes, called Organization Designation Authorization. This process, in which the aircraft manufacturer’s employees perform some of the safety tests and inspections with FAA oversight, reportedly saved the government body time and money.

That practice was examined at Wednesday’s Senate hearing.

Department of Transportation Inspector General Calvin Scovel III, who testified at the hearing, said the FAA will significantly change the oversight process for new aircraft by July. Speaking in vague terms, Scovel said that the changes would include new ways for the FAA to evaluate the self-certifying process.

Sen. Richard Blumenthal said that putting manufacturers in charge of their own safety audits was like putting “the fox in charge of the henhouse.” Saying he would introduce regulations to ban the practice of companies self-certifying, Blumenthal stated that “the fact is that the FAA decided to do safety on the cheap, which is neither safe nor cheap.”

Daniel Elwell, acting administrator of the FAA, said that using the plane manufacturers’ own employees to self-certify the planes has been “part of the fabric of what we have used to become as safe as we are today.” He noted that the FAA would need 10,000 more employees and $1.8 billion in additional funding to have FAA employees do all the labor of the self-certifying process.

In addition to the Senate hearing and the DOT IG’s probe, the Department of Justice is examining whether to bring criminal charges in the matter of the MAX 8 approval procedures.

Did the FAA decide that or did, uh, Congress decide to not fund them thereby forcing them to allow self-certification? I honestly don't know the answer. But, I've never known a gov't agency to voluntarily shed 10K jobs and $1.8B of annual funding.


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