Primarily for general aviation discussion, but other aviation topics are also welcome.
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#1809764
It was Boeing who did the repair on that JAL 747, admittedly not in Seattle. I'm not anti-either, for what's that worth.

Oldfart wrote:
mikehallam wrote:There have been some horrid 747 accidents, and not pilot error but poor detail design.
E.g. baggage doors blow out consequences, Japan and others.



Blow out baggage doors were DC10s
JAL 747 Fin loss, was due to sub standard repair, not conforming to Boeing repair scheme, Hardly Boeings fault.

Please be anti Boeing if you wish, but with the facts!
#1809766
Oldfart wrote:Blow out baggage doors were DC10s

A United 747 did have an in-flight baggage door loss and explosive decompression over the Pacific in the late 80s.

The aircraft was not lost, although there were several fatalities as rows of seats departed the cabin. :(

The cause was attributed to design and manufacturing faults.
#1809771
Dave W wrote:
Oldfart wrote:Blow out baggage doors were DC10s

A United 747 did have an in-flight baggage door loss and explosive decompression over the Pacific in the late 80s.

The aircraft was not lost, although there were several fatalities as rows of seats departed the cabin. :(

The cause was attributed to design and manufacturing faults.


Was that the one that the family of the deceased passenger paid for a 12,000 submersible to find the lost cargo door? And proved the initial NTSB report incorrect?
#1809772
Dave W wrote:
Oldfart wrote:Blow out baggage doors were DC10s

A United 747 did have an in-flight baggage door loss and explosive decompression over the Pacific in the late 80s.

The aircraft was not lost, although there were several fatalities as rows of seats departed the cabin. :(

The cause was attributed to design and manufacturing faults.


Was that the one that the family of the deceased passenger paid for a 14,000' submersible to find the lost cargo door? And proved the initial NTSB report incorrect?

My edit: yes it was the family of one of the deceased passengers. https://en.wikipedia.org/wiki/United_Ai ... Flight_811
Dave W liked this
#1813601
Brasilian airline first to put Max back into commercial service; American to follow:

https://www.bbc.co.uk/news/world-latin-america-55243961

https://www.cnbc.com/2020/12/02/america ... -jets.html
#1815554
Oldfart wrote:Obviously MCAS the final culprit.
But a good dose of Airmanship initially might have saved both.
Especially the last ET accident.
If you set TOGA on takeoff (ie Take off power) and leave it there until you hit the ground, rather complicates the handling.


Whilst true, it’d be really helpful if an aircraft didn’t confuse you so much that you had to work out “on the fly” how to stop it pointing at the ground because the procedures you’d been taught didn’t work.

If the aircraft I fly suddenly started madly trying to point themselves at the ground due to software issues, in a way I couldn’t quickly work out how to overcome, I’d be a bit upset if people were saying it was my fault rather than the aircraft.

You’re claiming both were due to bad airmanship?

Isn’t that what Boeing said at first “The 737 Max is fine, it was the crew”.

Not even Boeing said that for the second one though.
Charles Hunt, Stu B, Rob P liked this
#1815763
Software fixes can't overcome the fact that Boeing have built a fail active system that in the event of a particular single failure will run full nose down trim.
I can't understand why, after the grounding, Boeing didn't design a replacement angle of attack sensor with two separate vanes that would have to agree before the nose down trim was signalled. That would have properly solved the problem as a single sensor failure couldn't run nose down trim, but I suspect they thought they could write a few lines of code and get back flying in weeks.
A similar 4 vane 2 channel fail safe system drove the BAC1-11 stall protection system but I suppose there's nobody left at Boeing old enough to know of it.

BTW I don't see that reducing from T/O power could do anything but exacerbate the problem given that the system is only fitted to overcome excessive nose up divergence with high power.
#1815792
The aircraft had two AoA sensors fitted but Boeing had engineered it such that the software took data from only one sensor. This is a single point of failure, an absolute no-no for such a flight safety-critical system, a crass decision for which the Boeing safety engineers were obviously silenced. Ideally, such a system would be triple mode redundant with what is called 2oo3 (2 out of 3 voting), this system being tolerant of a single point of failure. With only two sensors, the system can be made fail-safe by 1oo2 voting whereby the software can at least recognise that the sensors disagree (it doesn’t know which one is faulty), and declare the MCAS system inoperable as a consequence.

Iceman 8)
#1816039
Many a/c over the years have had afterthought fixes for handling faults found when they've actually built and flown the prototype. I don't really think the problem is the Max requires MCAS its that the design of the MCAS system isn't fit for purpose, the hull losses are a result of MCAS failures making the aircraft unflyable. One could be forgiven for assuming that cost and a lack of third party supervision was a major factor in the "fix" that Boeing came up with and that cost still features in their determination to try and fix a fundamentally flawed system with software tinkering,
Stu B liked this
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