People send their broken, deformed, worn or corroded parts, and I help them figure out what went wrong. That’s my standard “elevator speech.” Well, it usually opens with “I’m a failure...” and then after a long pause, I add “analyst.”
Some people can’t wrap their heads around the fact that there’s a job called failure analyst. “So you fix the parts?” they ask.
No, I explain, I try to help them understand why they broke, deformed, wore out or got corroded so that we can then figure out either whose fault it is or what they might do to prevent additional failures.
I’d usually rather do the prevention-assistance than the assign-blame version of my job. But the hourly pay rate for assigning blame is usually higher. It’s also higher stress for the analyst, so most of my work is for manufacturing companies rather than attorneys. Some of the most interesting projects though, with the greatest learning opportunities, are the ones done for either attorneys or insurance companies.
Communication skills in presenting failure-analysis work are always as important as technical understanding of the physical situation for those jobs.
I just finished working on an insurance-related project. The part was obviously broken. Maybe you are thinking that all broken parts are obviously broken, but sometimes the parts are so damaged that it’s hard to tell if the crack happened before or after some other damage. I always like to go through a procedure in my mind and ask myself “What is the primary damage category?” OK, in this case, it was a crack.
It was even fairly obvious that it was a fatigue crack. In other words, it didn’t happen all at once. The crack grew over time. Sometimes it’s possible to tell quite closely how long it took for a fatigue crack to get to the point where the remaining bit of cross section is insufficient and the fragment is released.
Years ago, I looked at a propeller shaft from a boat that had been repaired, and within a few more trips, the propeller sank to the bottom of the lake. There were good records for the use of the boat – hours of operation, RPM of the motor, etc. – and I was able to show that the crack started growing right after the time of the repair. So we were able to conclude that the crack was probably a result of the accident that necessitated the repair in the first place.
I was able to do a similar analysis on an engine valve. I always feel lucky when the crack surfaces are well-preserved enough to see the details to allow such a determination to be made with a high degree of confidence.
This all leads us to the current investigation, and you can learn more about that next time in part 2.