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URL:  https://boards.fool.com/boeing-engineering-34159387.aspx

Subject:  Boeing Engineering Date:  3/17/2019  12:32 PM
Author:  qazulight Number:  555084 of 571929

Engineering case history from Twitter. If this is correct then we have another in a long list of lax regulation disasters.

There was a coal mine disaster

A shuttle disaster, or two

An oil well disaster

A train disaster

All directly related to the drive to economic efficiency.

I cannot predict how this works out. At best Boeing loses a lot of sales, or worst all the 737 Maxes get recalled and crushed and Boeing goes bankrupt wiping out investors employees and creditors.

It may also have long term political and geopolitcal fallout.

OR, a few tweeks to the plane, a few tweeks to pilot training and it is all good.

No position in aviation at all and avoid flying any commercial airline at all times. Piper Cubs and Stearmans are desired.


https://twitter.com/trevorsumner/status/1106934362531155974?...

***BEGIN TWITTER THREAD***

Some people are calling the 737MAX tragedies a #software failure. Here's my response: It's not a software problem. It was an

* Economic problem that the 737 engines used too much fuel, so they decided to install more efficient engines with bigger fans and make the 737MAX.

This led to an

* Airframe problem. They wanted to use the 737 airframe for economic reasons, but needed more ground clearance with bigger engines.The 737 design can't be practically modified to have taller main landing gear. The solution was to mount them higher & more forward.

During the course of developing the MCAS, there was a

* Systems engineering problem. Boeing wanted the simplest possible fix that fit their existing systems architecture, so that it required minimal engineering rework, and minimal new training for pilots and maintenance crews.

The easiest way to do this was to add some features to the existing Elevator Feel Shift system. Like the #EFS system, the #MCAS relies on non-redundant sensors to decide how much trim to add. Unlike the EFS system, MCAS can make huge nose down trim changes.

On both ill-fated flights, there was a:
* Sensor problem. The AoA vane on the 737MAX appears to not be very reliable and gave wildly wrong readings. On #LionAir, this was compounded by a

* Maintenance practices problem. The previous crew had experienced the same problem and didn't record the problem in the maintenance logbook. This was compounded by a:

* Pilot training problem. On LionAir, pilots were never even told about the MCAS, and by the time of the Ethiopian flight, there was an emergency AD issued, but no one had done sim training on this failure. This was compounded by an:

* Economic problem. Boeing sells an option package that includes an extra AoA vane, and an AoA disagree light, which lets pilots know that this problem was happening. Both 737MAXes that crashed were delivered without this option. No 737MAX with this option has ever crashed.

* Pilot expertise problem. If the pilots had correctly and quickly identified the problem and run the stab trim runaway checklist, they would not have crashed.
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