ET EXTRA: Protecting Your Life: Customers Claim “Fixed” Toyotas Are Still Accelerating

09 Mar

Engineering Thinking Extra Is A Short Review Of A Current Hot Topic

“…the Department of Transportation released data Thursday showing that more than 60 people have complained of sudden acceleration incidents in vehicles that have been repaired by Toyota as part of the recalls to address the problem.”
Los Angeles Times, “Top lawmakers want more data from Toyota,” 6 March 2010.

The problem with Toyota is not that they have experienced a problem. All technology products have problems, although for high quality products the problems are usually minor and only affect a small percentage of products sold.

Problems occur because, despite our advances in technology, it is a simple fact that it’s not humanly possible to achieve a perfectly safe and reliable product. Plus, the price tag for trying to achieve perfection always reaches a point where the customer is not willing to pay the price. We all would be safer if we drove vehicles that were built like tanks, but their low fuel efficiency, cumbersome performance, and high price would make them much less attractive, all things considered, than the less-safe autos that we willingly purchase today.

Also, technology is not capable of completely compensating for human error. Drivers can mistakenly step on the gas pedal rather than the brake pedal, and in a panic keep their foot jammed to the gas pedal because they think they are stepping on the brake. (In engineering parlance, this is an example of a feedback loop that has — because of the application of foot to incorrect pedal — changed abruptly from a stable loop to a completely unstable one.) Although I have not seen any convincing data on how often we should expect human error to create “unintended acceleration” events, the hypothesis is plausible and should not be dismissed.

No, the problem with Toyota is not that they claim that human error is sometimes to blame, or that they have some product defects. The problem with Toyota is their response to the issue, which has been documented to be one of delay and obfuscation (link). This demonstration of poor character is what may kill Toyota.

An avenue of investigation that I have not seen addressed by Congress is a request to review Toyota’s design validation documentation. This would be the set of analyses and test reports that are the gold standard for high-reliability products. The analyses would include a Worst Case Analysis and a Fault Tree or a Single Point Failure Analysis. In my view, if these documents do not exist, it indicates that Toyota has not adopted “best engineering practices” regarding safety-critical products.

If they do exist, they can be reviewed for thoroughness and accuracy. And if they are thorough and accurate, there is a high likelihood that the problem has already been identified. If so, this means that Toyota ignored their engineers for cost-containment purposes, to the detriment of public safety. Toyota is acting as though this indeed is what happened.

Toyota: show us your analyses.

-Ed Walker


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