Rudder issue that plagued the Boeing 737 throughout the 1990s

In both cases, there was a certain inevitability given the processes at work, the conditions, the changes and the difference between engineering reality and what is presented in the FAA Type Certification process as the basis for the modification of the Type Certificate. As an engineer working on aircraft, one thing is for certain, engineering data is laundered to the bare minimum in the interests of certification. This is in contrast to the engineering NASA does. The cert process does not achieve transparency, as it is a legal not an engineering process.

One can blame manufacturers, but there really is no way for them to be transparent and ever ship anything (ref. Lear Fan). I am not, however, advocating retracting any responsibility from Boeing. They must bear the responsibility for their product. I am only saying that we have created an environment as a country that makes it unlikely we will see the behavior we desire from manufacturers. As a person who likes to land the same number of times I take off, my interest is in helping the government improve as well as the manufacturers.

So Boeing decided to conclude that the existing system was sufficient. And they proved it to the FAA. There is no precedent or standard applied to the parts of the airplane that are not changed, once they are deemed not to need changing. This is similar to the housing code. Replace a socket in a house with knob-and-spool wiring, and you do not need to fix a thing. Rewire a bedroom in a house with knob and spool wiring, and the code will not let you put new knob and spool wiring in, one must then bring the house's electrical system up to code.

The reason there still is a 737 is the tremendous economic benefit afforded to manufacturers who use safety analysis to show that the previous iteration of the aircraft's systems are sufficient given proposed changes on the aircraft. That's why it has ridiculous engine nacelles, ridiculous landing gear, in many 737's ridiculous avionics. A new airframe is required, but the cost of a new airframe's certification is much greater than the hacky re-certification of an old type certificate obtained when standards and processes were very different and much out of date.

That's why we have a term "criminal negligence", because sometimes it's impossible to tell malice from incompetence.

So the law basically decided, "Well, fuck this, if you do something as stupid as (putting a faulty brake on a train, for example), then you deserve to go to jail, and we don't care if you were actually thrilled to kill passengers or were simply too stupid to understand what you were doing."

https://nsc.nasa.gov/resources/case-studies

This one is interesting:

In March 2010, a 29-year-old shift nurse left her job in Atlanta, Georgia and headed to her boyfriend’s house. She was driving her 2005 Chevy Cobalt on a two-lane road as she approached a half-mile downhill straightaway. As the road leveled after the straightaway, she approached an area where some rainwater had accumulated. Shortly after encountering this section of roadway, she apparently lost control of her Cobalt as it hydroplaned across the center line. The rear passenger side of her car was struck by an oncoming Ford Focus, causing the Cobalt to spin off the road and fall 15 feet before landing in a large creek around 7:30 p.m. The impact of the crash broke the nurse’s neck, an injury that led to her death shortly after she arrived at the hospital.

While this tragedy might sound like a typical crash scenario, it was particularly puzzling to the victim’s parents. Why? According to Atlanta magazine, she always wore her seat belt and never had a speeding ticket. So how did she suddenly lose control of her car on that fateful evening? Sadly, this unsettling question remained unanswered until several years later—after many more drivers suffered similar fates.

...

The ignition switch did not meet the mechanical specifications for torque and required less force to turn the key than its designers originally ordered. If the driver’s knee hit the key fob, the car would often turn off, causing stalling at highway speeds and disabling the airbags.

https://nsc.nasa.gov/features/detail/hidden-hazards

Edit: apparently NASA is checking referrer and you can’t follow this link directly. It’s the third case study down the page from the first link.