标签: destructive

As a "newbie" electrical engineer at an aerospace design company in Louisville, Colo., I have been learning the flight hardware design techniques, testing procedures and the rules that go along with troubleshooting a problem. It usually involves some extreme amount of paperwork, three signatures and highly skilled technicians trying to read through a rework or troubleshoot steps that somehow always come under scrutiny, thus making me feel like ... well.... a newbie. In the past 14 years of my career, I served as a communications repair technician in the U.S. Marine Corps, and, after I was honourably discharged, I worked at other small companies as an experienced technician using the skills I had gained in the Marine Corps. During this time, I worked part-time and used my GI bill to obtain my EE degree from the University of Nevada, Reno. While earning my degree, I spent many hours working in the aerospace field of study. Teaching old dogs old tricks When I moved on to the avionics group with my current employer, I was a semi-expert on sensors for micro satellites. I was proud to find my niche and felt like I could show a bit more of my knowledge without getting myself in a bind or be made fun of by my peers. And, until a few weeks ago, I never really had the right moment to "show them what I got!" While we were working a failure on a circuit board, management wanted to conduct a destructive analysis to determine a root cause for the failure in the flight board...doing this would take time and cost a bit more than our group wanted to spend. And, at the time, the board and component failure had become the "long pole" (the biggest issue of concern) in our program and was given the highest priority. I quietly said to my boss, "Why don't we 'Huntron track it?'" Based on a name-brand piece of test equipment called a Huntron Tracker, this was a term we had used a lot in my days at a fourth-echelon electronic repair facility in the Marines. Of course, my boss didn't know about any of this, so to him I must have sounded like a "goof." And, my "whisper" was a little louder than I had planned and resulted in everyone at the table looking up at me in total confusion. I said quickly, "You guys know what I am talking about right? Using a curve tracer to compare a component to a known good component to look for a difference in the 'signature'.." (Insert sound of crickets here). Still nothing was changing their looks, so I started over with a detailed account of how I used this test equipment while a tech and how it saved us many hours trying to troubleshoot down to the root cause of the failure. Once they all were on the same page, they pointed to me to conduct the test and prepare the procedure, and since they knew no one person would have a clue what I was describing, it would be up to me to conduct the test first-hand. For a split seconded I realised that all my years of training and experience hadn't been for not, and that I would now be able to call on my "bag o' tricks" without having to feel like I was talking nonsense in the aerospace world. Solder issues I troubleshot the circuit to a compare-and-hold IC that had inductive shorts to the 5V reference on the wrong pins—in fact it was TWO pins that had been damaged or shorted—looking closer, I realised that, during the QA inspection, the true problem was missed. On a metal can-integrated circuit, the soldering had bubbled up to the can and thus created a semi-inductive short once the board and IC were operating in a hot environment. It was so hard to see and required that the board be tilted and reviewed under a microscope, but I was able to show that the quality of the solder on this component had caused the failure. A review and circuit analysis was also conducted, and it showed that the type of intermittent problem could be traced back to this component. (Figure 1, below, the IC with shorted pins). Figure 1: Solder Blobs! Yikes! After I gave my full report and provided my findings, I felt like I had really come through for my team. I had several people give me a pat on the back, which motivated me to continue speaking from my experiences and show that, just because I was new to the company, I still had some area of expertise that no one else on the team had... and I felt proud to help on a problem that was given the highest priority to solve. - William Davison William Davison recently moved from Northern Nevada to the Denver area to work in the aerospace industry after obtaining his electrical engineering degree from University of Nevada, Reno. He keeps busy with his hobbies (old BMW car restorations, LEGO Robotics and Halloween effects/costumes) and continuing his education. He is currently going to Colorado State University with a focus on obtaining his Systems Engineering Masters.