Author Topic: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'  (Read 78272 times)

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Online BravoV

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #1175 on: October 23, 2019, 02:30:34 am »
Ref - https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/risk_management/ss_handbook/media/chap3_1200.pdf

Everything related to FAA is pointless, as its now considered no better than those easy to lobby, getting cozy ... to be bribed government regulatory/safety related institutions like in those piss poor developing countries.

Even Boeing managed to survive this event, the cost of selling any US made airplanes, not only from Boeing, will be sky high as now every developed countries need to re-certify it, as FAA's certification considered a junk now.

A bold move from gov. or politicians are desperately needed now than ever, especially for international markets.
« Last Edit: October 23, 2019, 02:37:10 am by BravoV »
 

Offline SilverSolder

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #1176 on: October 23, 2019, 11:45:11 am »
They're under economic pressure to compete. It's not like stretching type certificates for derivative models is a novel thing or Boeing-specific.
The 737-900 is leagues different from the 737-100.
The Airbus A318, A319, A320, and A321 are all built on a common type certificate (EASA.A.064) and I count 47 individual models/variants of airplanes built on that type certificate.

Absolutely - and if the job had been done properly, nobody would have had a problem with it.

When all is said and done, Boeing and the FAA released a product that was - overall - flawed enough to be a real problem.  They somehow failed to strike the right balance between financial interests and engineering realities.  This can only be fixed by raising the level of play substantially to regain trust.
 

Offline Gyro

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #1177 on: October 23, 2019, 11:51:48 am »
A BBC news report - it looks as if heads have started rolling at Boeing, prior to their Q3 results publication later today...

https://www.bbc.co.uk/news/business-50151573

The Indonesian investigators final report on the Lion Air crash is expected to be published on Friday.


EDIT: The story and content have since been updated from the previous title and is now saying that Boeing expect the 737MAX to be flying again by the end of the year.
« Last Edit: October 23, 2019, 04:47:15 pm by Gyro »
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Offline GeorgeOfTheJungle

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #1178 on: October 24, 2019, 09:25:00 am »
The FAA is going to say they need more taxpayers $ to do their job right... That's how the public sector works!
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Offline StillTrying

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #1179 on: October 24, 2019, 11:13:30 am »
EDIT: The story and content have since been updated from the previous title and is now saying that Boeing expect the 737MAX to be flying again by the end of the year.

It's the only practical way to get them there.  https://www.airplaneboneyards.com
CML+  That took much longer than I thought it would.
 

Offline sokoloff

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #1180 on: October 24, 2019, 11:20:33 am »
Boeing is flying 737-Max under ferry permits or experimental flight test protocols now and has been for a while. They’re still building them and relocating them to other fields.

When the financial news media says “will be flying”, they mean in revenue service not merely leaving the ground.
 
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Online SiliconWizard

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #1181 on: October 24, 2019, 06:07:05 pm »
They're under economic pressure to compete. It's not like stretching type certificates for derivative models is a novel thing or Boeing-specific.
The 737-900 is leagues different from the 737-100.
The Airbus A318, A319, A320, and A321 are all built on a common type certificate (EASA.A.064) and I count 47 individual models/variants of airplanes built on that type certificate.

Oh of course, this is common practice, and there's nothing fundamentally wrong with it.

I (along with many others) just think Boeing has gone a step too far with the 737MAX.

There's something to also consider here. Yes the 737 essentially competes with the A320 family. But the 737 was released in 1968. The A320 (first of the family AFAIK) in 1988, 20 years later. Sure both lines have evolved significantly, but still.

Impressive longevity, but I guess at some point it becomes unreasonable to keep milking the cow.
 

Offline MT

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #1182 on: October 29, 2019, 10:49:20 pm »
Boing flies into darker weather!

Spirit Florida orders 100 planes from AirBus
https://www.zerohedge.com/markets/boeing-backlash-begins-spirt-airlines-orders-100-new-airbus-planes

India orders 300 planes from Airbus!
https://www.zerohedge.com/markets/boeing-backlash-indias-indigo-order-300-jets-airbus

Blancoliro says it 737Max will be certified and out fly soon, Senate hearing.
« Last Edit: October 29, 2019, 11:11:28 pm by MT »
 

Offline bw2341

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Offline sokoloff

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #1184 on: October 30, 2019, 01:16:30 am »
Indeed. Crew fights with electric trim from 23:25:27 through 23:31:46 activating nose up manual trim 32 times for 143 seconds (of the 379 elapsed seconds, or 38% of the time).
That's absolutely abnormal and yet the crew never recalls the runaway stabilizer trim memory items nor calls for the runaway stabilizer checklist.

They were dealt a confusing situation with the IAS DISAGREE and angle of attack difference. That may have contributed to their failure to identify the appropriate response.
 

Offline GeorgeOfTheJungle

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #1185 on: October 30, 2019, 08:23:26 am »
That may have contributed to their failure to identify the appropriate response.

At least the captain (somehow, inadvertently) sensed that trim was being a problem, because he kept correcting it good enough, obeying the #1 rule fly the plane, but the FO...

Quote
At 23:30:48 UTC, the Captain asked the FO to take over control of the aircraft

...failed big time to fly the plane!

I too wonder why the captain didn't flip the stab trim cutout switch after all that fighting against auto trim, or put the flaps back to pos 1. He should have known to do that. I wouldn't expect the FO to grasp or infer any of that, much less in a sec, because there's a reason why they're still FOs and not captains: lack of experience.
« Last Edit: October 30, 2019, 08:27:11 am by GeorgeOfTheJungle »
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Online SiliconWizard

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #1186 on: October 30, 2019, 02:56:15 pm »
This part says a lot though:

Quote
In the event of multiple MCAS activations with repeated electric trim inputs
by flight crew without sufficient response to return the aircraft to a trimmed
state,  the  control  column  force  to  maintain  level  flight  could  eventually
increase to a level where control forces alone may not be adequate to control
the  aircraft.  The  cumulative  mis-trim  could  not  be  countered  by  using
elevator alone which is contrary to the Boeing assumption during FHA.
 

Offline bw2341

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #1187 on: October 30, 2019, 03:37:45 pm »
That's absolutely abnormal and yet the crew never recalls the runaway stabilizer trim memory items nor calls for the runaway stabilizer checklist.

Warning! I’m not involved in aviation in any way. My posts may be mistaken.

My impression is that retrimming the plane is like breathing for a pilot. You climb, descend or turn and you retrim. A few minutes pass while on autopilot and you retrim. You scratch your belly and you retrim.

If you’re always adjusting the trim on instinct, what threshold do you need to notice that you are trimming more than normal?

A pilot’s insight would be enlightening. How often is normal for manual trimming? Also, how often does MCAS and the previous Speed Trim System normally activate?

My impression is that MCAS and STS would make detecting runaway stabilizer very difficult. You’re manually flying along and the trim motor activates briefly. Without hard guidelines of what’s normal, how would would you know if it’s too much?
 

Offline sokoloff

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #1188 on: October 30, 2019, 04:39:13 pm »
It is close to breathing in terms of how much concentration it requires to activate, but it’s also quite normal that trimming occurs primarily around speed or configuration changes. Raise the flaps? Might need to trim. Accelerate to second stage climb, might need to trim. It’s not the case that you’d be trimming over and over, only to have the airplane trim against you (with associated audible and visual indications) right afterward.

With that amount of trim activity required without any associated configuration or speed change, it would be flagged as abnormal to most pilots.

For context only, I have about 1300 flight hours in several different high performance single and twin piston airplanes but only have somewhere around 20 jet hours, including around 5 in a level D full motion 737 sim.
 

Offline bw2341

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #1189 on: October 30, 2019, 06:27:12 pm »
Wow!

Thank you for your direct insight and knowledge.

The report suggested that the stab trim motor may have gone unheard due to the noise from the continuous stick shaker activation. I found that very alarming. Wouldn’t incorrect activation of the stick shaker be serious enough to declare MAYDAY right away?

The crew of the previous flight who successfully recovered the same faulty aircraft decided to fly the whole flight with the sticker shaker activated! That seems crazy to me.
 

Offline bw2341

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #1190 on: October 30, 2019, 06:49:29 pm »
To bring this report on topic on ”The biggest T&M forum on the net”, the incorrect use of an angle measuring instrument led to the faulty repair of the AoA sensor.

The approved instrument was substituted with one that had an extra switch labeled REL/ABS. If the instrument was switched out of absolute mode into relative mode by mistake, it would lead to an AoA sensor carefully aligned to a completely random incorrect angle.
 

Offline floobydust

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #1191 on: October 30, 2019, 07:20:00 pm »
The repaired AoA sensor left it with a 21 degree offset, which was not noticed by Lion Air's maintenance team.
Xtra Aerospace was not qualified to do the repair of the AoA sensor in the first place, now the FAA revoked their repair certification license.

https://www.aviationtoday.com/2019/10/28/lion-air-737-max-final-accident-report-cites-aoa-sensor-mcas-as-contributing-factors
 
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Offline Gyro

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #1192 on: October 30, 2019, 07:43:37 pm »
Xtra Aerospace was not qualified to do the repair of the AoA sensor in the first place, now the FAA revoked their repair certification license.

In fact their web site no longer appears to exist and their parent company, Wencor Group, has no mention of them on their website. Not surprising if you get your certification pulled I suppose.
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Offline AG6QR

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #1193 on: October 30, 2019, 10:06:09 pm »
Wouldn’t incorrect activation of the stick shaker be serious enough to declare MAYDAY right away?


Probably not Mayday, perhaps Pan-pan, or maybe a routine return to the departure airport.  Particularly when combined with inappropriate trim activation with an unknown (at the time) cause, it's a matter of serious concern.

Quote

The crew of the previous flight who successfully recovered the same faulty aircraft decided to fly the whole flight with the sticker shaker activated! That seems crazy to me.

Yes, you aren't the only one who sees it that way.
 
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Offline sokoloff

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #1194 on: October 31, 2019, 03:19:49 pm »
The priorities, in order, are aviate, navigate, communicate.

Aviate: don’t crash the airplane
Navigate: take it where you want to go
Communicate: let ATC know what’s going on

In this case, saying or not saying Mayday has no practical effect. They were already getting everything they needed from ATC (nothing more would help). I doubt either pilot of either crew had any doubt that they were facing a serious emergency.
 

Offline bw2341

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #1195 on: November 02, 2019, 01:38:43 pm »
The report addressed this topic. Yes, the pilots should have ignored ATC and kept all their attention on handling the aircraft. Instead, the pilots responded to the eight heading instructions given by ATC.

Declaring PAN PAN or MAYDAY would have kept ATC quiet, reducing their workload. ATC would have gave them priority, keeping other aircraft out of their way.
 
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Offline bw2341

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #1196 on: November 02, 2019, 02:07:14 pm »
Xtra Aerospace was not qualified to do the repair of the AoA sensor in the first place, now the FAA revoked their repair certification license.

This is aftermath, but the events leading up to the mistake are more subtle and insidious.

Xtra had to justify the substitution of the angle measuring equipment with documentation. The people who wrote the test equipment equivalency report were either incompetent or unqualified as they missed the extra mode switch and lower accuracy of the substitute equipment.

The report was accepted by the local FAA Flight Standards District Office, who also missed the problems.

 

Offline AG6QR

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #1197 on: November 02, 2019, 05:15:02 pm »
Something to remember is that, in previous generations of the 737, a faulty AoA sensor could not cause the plane to crash.  It would cause one AoA display to be wrong, and perhaps activate one stick shaker.  That's not critical.

Only when MCAS was introduced did Boeing give a faulty AoA sensor the power to cause trim changes.  And they didn't tell anyone about it, at least not pilots or operators.

So it's understandable that people who didn't know about MCAS would be a bit unconcerned about an AoA sensor.
 
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Offline bw2341

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #1198 on: November 02, 2019, 07:03:05 pm »
and perhaps activate one stick shaker.
Reading these kinds of reports has made me appreciate the finer details. Yes, this kind of faulty sensor will signal a single computer out of two and activate a single stick shaker out of two. But, as mentioned in the report, both control wheels are physically linked. A single stick shaker will be felt on both wheels. It may not be possible to distinguish a single shaker versus a double shaker activation.


Only when MCAS was introduced did Boeing give a faulty AoA sensor the power to cause trim changes.  And they didn't tell anyone about it, at least not pilots or operators.

So it's understandable that people who didn't know about MCAS would be a bit unconcerned about an AoA sensor.

The previous STS uses the same methodology as MCAS.  Computer controlled trim is used to enhance control feel during manual flying. It does not use the AoA sensor as an input.

As fly-by-wire is becoming the norm, perhaps more work is needed to improve AoA sensors and fault detection. Airbus had a few upsets and one crash where two stuck AoA sensors caused the rejection of the third.

https://www.flightglobal.com/news/articles/analysis-how-airbus-fought-its-own-pitch-battle-457574/
 

Offline floobydust

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Re: Lion Air crash: Jakarta Boeing 737 'had prior instrument error'
« Reply #1199 on: November 02, 2019, 09:14:23 pm »
This isn't failed engineering, needing improving sensors and fault detection.
It's unbridled corporate greed and corruption, at the executive level.

MCAS had already been properly engineered. From Muilenburg's testimony before Congress this week:
"Michigan Republican Representative Paul Mitchell asked why the 737 Max’s version of MCAS had key differences from a midair refueling tanker Boeing supplies to the U.S. Air Force. He pointed out that the Pentagon required that the KC-46 tanker’s MCAS system activate only once, when the civilian application could -- and did -- fire repeatedly, he said.

“Why the difference? What motivated that?” the lawmaker said.

John Hamilton, chief engineer of Boeing Commercial Airplane division, cited specifications set by the Air Force. Muilenburg said the tanker’s MCAS system was designed for different flight scenarios than the 737 Max’s version. The Air Force has said the KC-46’s MCAS systems incorporated data from two angle-of-attack sensors, rather than one sensor as originally designed on the 737 Max."

When your customer tells you how to do airplane engineering safety  |O

He's still among the highest paid CEO's at $23.4M, including a $13.1M bonus, 27% increase from the previous year.
Imagine getting paid that much despite killing 346 people and $9B in losses.
 


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