Some nations ground 737 Max 8 planes after second catastrophic crash in five months (1 Viewer)

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Bill said:
The news is out now that the AoA sensor on the Ethiopian Airlines incident may have been damaged during the flight by a bird or foreign object of some sort. My first thought after learning of the pitching problem is that there must have been some false/faulty data coming from that sensor. It was reported yesterday that the pilots initially turned off the power to the trim motors, which would have been the correct procedure according to the emergency checklist. But then they inexplicably turned them back on when they were unable to regain control of the aircraft.

It seems they were at a loss to understand the issue at hand as they struggled to keep the nose of the airplane pointed skyward. It appears that the new software is going to have to provide for a simple and immediate override of these automatic systems which will allow pilots to quickly restore the aircraft to the proper flight attitude.
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Hopefully they remember how to hand-fly the A/C. :hihi:

@satcom_guru is a good Twitter follow for this.

 
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So, for ET302 (Ethiopian Airlines) it seems that the 1 AOA vane that fed info to MCAS was struck by something, most likely a bird. This gave the CA and FO different IAS readings. This is just after takeoff, so Autopilot is not engaged. These are two of the three conditions needed for MCAS to engage. Once the flaps were retracted, MCAS kicked in being that is the final event needed to trigger the system.

MCAS pushes nose down and the aircraft picks up speed. The pilots correct the "nose down" attitude. MCAS pushed the nose down again and the aircraft picks up more speed. The crew then disables the electric trim. Then they try to manually trim out the aircraft, but because of the speed this aircraft has picked up the gravitational forces on the control surfaces prevents the crew from making the corrections. After discovering they cannot manually make a correction, they enable the electric trim again, but this results in MCAS engaging and pushing the nose down again.

It is my understanding that all of this happened at 1,000 feet and below which doesn't provide a lot of altitude to work with in correcting the problem. It is my understanding that if the bird, object, etc. had struck the AOA vane on the other side of the aircraft then none of this happens. If I am not mistaken, one of the changes being offered by Boeing is that the MCAS pulls data from BOTH AOA vanes.

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Today they released that the failed AOA vane for the Lion Air flight never functioned correctly when it was installed. It was a rebuilt part from Xtra Aviation in Miramar, FL which is not unusual in commercial aviation. Regardless of a new or rebuilt parts, ops checks are to be performed after installation verifying that it works correctly when it's placed back into service as sometimes these parts are sensitive and/or become damaged during shipping. At this time it isn’t clear why that required test didn’t identify that the part wasn’t functioning properly.
 
Apparently in both flights, the pilots followed protocol exactly.

There was only a single sensor feeding the MCAS system.

Boeing is admitting fault in the software due to bad data.

I'd imagine that Attorneys will have a field day with Boeing after the certification process and not having any redundancy built into a single sensor.
 
MLU said:
Today they released that the failed AOA vane for the Lion Air flight never functioned correctly when it was installed. It was a rebuilt part from Xtra Aviation in Miramar, FL which is not unusual in commercial aviation. Regardless of a new or rebuilt parts, ops checks are to be performed after installation verifying that it works correctly when it's placed back into service as sometimes these parts are sensitive and/or become damaged during shipping. At this time it isn’t clear why that required test didn’t identify that the part wasn’t functioning properly.
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Xtra is part of Wencor. Not my company.

I wouldn't put the blame on them, but there will still be a full investigation into the repair approval, records, if anything is left to run a Failure investigation ont he part its self, and what the pre-check test you're mentioning showed (was it recorded?).

It also depends on what they mean by "never functioned correctly" how far off? Consistently off by a certain value, or variable?
 
Saint_Ward said:
Xtra is part of Wencor. Not my company.

I wouldn't put the blame on them, but there will still be a full investigation into the repair approval, records, if anything is left to run a Failure investigation ont he part its self, and what the pre-check test you're mentioning showed (was it recorded?).
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Absolutely and it's why I made mention of parts being "damaged during shipping". I have seen plenty of times where a part arrives and when it's installed, doesn't function correctly.

Saint_Ward said:
It also depends on what they mean by "never functioned correctly" how far off? Consistently off by a certain value, or variable?
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I know that every part and installation has it's process, but failing an ops check is failing an ops check. We already know that Lion Air's Maintenance program is under scrutiny after the B73M accident. This seems to be just another issue in their program.
 
superchuck500 said:
I don't know where else to put this but holy crap, I bet some passengers on that flight will never fly again.

www.flightradar24.com

Flightradar24 data for Air Astana KC1388 E190 loss-of-control incident

On 11 November, Air Astana KC1388 an Embraer E190 (registration P4-KCJ), departed Alverca Airport following a heavy maintenance C-check.
www.flightradar24.com www.flightradar24.com
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Put it in right...(actually, looks like instructions made it more complicated than before).

Portuguese authorities published their preliminary report on the incident on 31 May, finding a reversal in the aileron cable assembly. You may read the full report here (PDF).
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The report isn't loading, but I found this...

The crew realised that the ailerons were behaving erratically and therefore any command for the aircraft roll was kept to its minimum. Having gained some control of the situation, the crew flew East, searching for better weather conditions and started to follow the flight plan defined by the air traffic control for an emergency landing in a suitable airport, with good weather and physical conditions to deal with the sustaining aircraft control difficulties.
At this moment, when the pilots were able to keep altitude and heading, and had sufficient visual references, the aircraft was joined by a pair of F-16 fighters from the Portuguese Air Force that were scrambled from the Monte Real Air Base. They assisted in guiding to Beja Air Base, which had been selected in the meantime as the best emergency landing option.
After two non-stabilised approaches, the aircraft managed to land safely on runway 19L at the third approach. The intended runway was 19R, but due to drift, they finally managed to land on the left runway.
All on board were physically and emotionally shaken, one of the passengers sustaining a leg injury.

Update
On May 31, 2019, GPIAAF Portugal published in investigation update, reporting that a detailed examination of the aircraft flight controls showed an incorrect ailerons control cable system installation.
A modification carried out in accordance with an Embraer Service Bulletin (SB 190-57-0038) changed a cable routing support near rib 21 of the aircraft. This change made it harder to understand the maintenance instructions and spot reversed aileron cables.
During maintenance, the Engine-indicating and crew-alerting system (EICAS) displayed a caution message: "FLT CTRL NO DISPATCH". This meant that one of the components of the flight control system had failed. Troubleshooting activities by the maintenance service provider, supported by the aircraft manufacturer, lasted 11 days. However, the ailerons' cables reversal was not identified in this period.
Also, prior to departure, the ailerons incorrect operation caused by the control cables reversal, was not identified in the aircraft operational checks (flight controls check) by the operator crew.
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Not a good look. The financial channels are talking about CEO replacement and possible criminal investigations.
 
superchuck500 said:


Not a good look. The financial channels are talking about CEO replacement and possible criminal investigations.
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Gee, who would have thought the FAA allowing multinational corporations self certify could go wrong? Meanwhile, FAA spending all of it's time worrying about drones flying too close to clouds or over people.
 

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