BBC1 - Boeing’s Killer Planes

[Steve vRS]

Quite an emotive title.

Watching it now.

[Europa1]

...and an unequivocal conclusion.

There must have been some sweating in the BBC's legal team!

[dodgepot]

I haven't read much about the whole saga, but I was gobsmacked that the system relied on a single sensor and they thought that was acceptable

[Steve vRS]

Me too. In the chemical industry, a safety critical instrumented function almost always has redundancy built in. If not, it’s proof test time (calibration) is extremely small.

[louiebaby]

I haven't seen the BBC documentary yet, but found this an interesting view:

https://www.youtube.com/watch?v=BfNEOfEGe3I

I've seen quite a lot of the Wendover stuff.

[48k]

Steve vRS said:

Me too. In the chemical industry, a safety critical instrumented function almost always has redundancy built in.

So - exactly the same as the airline industry then

[Steve vRS]

Selective quote.

If there is one safety system, it ends up being rigorously tested. And then only if it can be demonstrated that the cost of the retrospective installation of a redundant system is grossly disproportionate.

[Tempest_5]

No one seems to have picked up on the fact this isn't the first time the 737 has had an "issue". Back in the 90's there were a series of accidents where the aircraft would roll over and dive into the ground. It was traced to the rudder actuator having a failure mode where it could suddenly go to the extreme of it's movement. This happened on a couple of aircraft during landing where there was no time to correct it. It finally happened to an aircraft at height and the pilots were able to recover the situation, confirming what had happened.

https://en.wikipedia.org/wiki/Boeing_737_rudder_is...

[MarkwG]

Tempest_5 said:

No one seems to have picked up on the fact this isn't the first time the 737 has had an "issue". Back in the 90's there were a series of accidents where the aircraft would roll over and dive into the ground. It was traced to the rudder actuator having a failure mode where it could suddenly go to the extreme of it's movement. This happened on a couple of aircraft during landing where there was no time to correct it. It finally happened to an aircraft at height and the pilots were able to recover the situation, confirming what had happened.

https://en.wikipedia.org/wiki/Boeing_737_rudder_is...

I suspect that's because the rudder hard over problem was confined to a relatively small number of aircraft, after a considerable time in service & took a while to deduce due to limitations in the technology of the day to remotely report what had happened, whereas the MAX issue seems to be more a function of inadequate safeguarding of the design & regulatory process, very soon after the first flights & the volume of data available is of far higher quality. The end results tragically the same, but the causes & consequences are likely to be very different.

[Eric Mc]

At the time of the rudder hard over problems, the 737 had already been in service for over 20 years (entered service in 1968). It seemed to be an extremely rare issue that only occurred in very limited circumstances - which is why it manifested itself only after decades of service.

This problem is far more immediate and fundamental to the way the 737 Max has been designed and certified.