How much stuff do you carry on your keyring? Besides keys, I mean. Some minimalists like my wife carry car keys separately from other keys, with nothing attached except maybe a small plastic tag to make it easier to find in her purse. Other people, many of whom are younger, may carry a whole bundle of stuff on their keyrings: those little barcode cards that give you discounts at retailers, miniature plastic poodles, handcrafted bits of knitted yarn, and I don’t know what all. But it probably never occurred to you to think that a heavy keyring could be hazardous to your health.
Brooke Melton probably wasn’t thinking of her keyring one rainy March night in 2010. She was driving her 2005 GM Cobalt when the ignition switch suddenly moved from “run” to “accessory.” This had the unfortunate effects of killing the engine, disabling the power steering, and turning off the airbags. The sudden loss of power caused Melton to cross into oncoming traffic. The Cobalt crashed into another car at 58 mph and wound up in a creek, killing Melton and starting a chain of events that revealed the true cause of more than a dozen similar crashes going back more than half a decade.
As long ago as 2001, engineers at General Motors knew that a certain model of ignition switch assembly that was later used on a number of models had a problem. The mechanical design of an ignition switch is a compromise, as are so many things in engineering. Most mechanical ignition switches use a device called a detent, which divides the continuous rotation of the switch that would occur without the detent into a small number of discrete positions, typically four: “off”, “accessory”, “run” and “start.” If the detent provides too much resistance, the switch will be hard to turn and might eventually wear so much that it would fail to work at all. But if the torque (twisting motion) required to move the switch is too small, you take the risk that unbalanced forces resulting from heavy stuff on a keyring, for instance, may spontaneously make the switch turn from one position to the other. This is apparently what happened to Brooke Melton and the 12 or more other drivers who died in ignition-failure accidents in GM cars having the suspect assembly.
At this remove, it is obvious what GM should have done. The guilty part, No. 10392423, should have been redesigned with a more forceful switch detent plunger—a 57-cent piece that consists of a rounded plastic cylinder backed by a coil spring. It is the force exerted by this plunger that sets the amount of torque needed to turn the ignition key from one position to the next. Changing the spring fixes the problem by increasing the torque needed to turn the key from “run” to “accessory.” Then, the ignition assembly part number, or some documentation somewhere, should have been changed to reflect the fact that the new part was substantially different. And GM should have recalled however many cars they had sold with the defective ignition switch and replaced them free of charge.
If this had been done early, before too many cars had been sold with the defective ignition, it would have cost something, but the earlier such things are dealt with properly the less expensive they are. But at the time, a few other things were happening at GM that provided distractions, namely, bankruptcy. So matters drifted along, and at some point, Delphi (the company that makes the switch in Mexico for GM) changed the plunger to fix the problem. There is contradictory information as to whether Ray DiGiorgio, a GM engineer, approved a design change in April of 2006 making this fix. He has testified that he did not, but a Congressional committee claims it has documentation showing that he did. Whatever was done in 2006, it had no effect on the thousands, if not millions, of cars already on the road at that time with defective switches.
After Brooke Melton’s death, her parents decided to sue GM. Their lawyer, Lance Cooper, hired a consulting materials engineer named Mark Hood to look into why the ignition turned off—an event that was documented by the car’s black box. After plowing through numerous Cobalts of various vintages in junkyards, he discovered that the critical plunger had been silently altered around 2006 or 2007. Switches made before then took less torque to turn off than the newer switches. Armed with these facts, Cooper took depositions from GE engineers and reached a settlement with the firm. But the publicity surrounding the lawsuit attracted enough attention that others with similar crash incidents on their hands began looking into the matter. And just last week, GM CEO Mary Barra testified before Congress about the whole thing.
To her credit, Barra took action to issue massive recalls, affecting some six million cars, on this and other problems within weeks after learning about them when she took the helm of GM in January of this year. But these recalls are too late for Melton and at least a dozen others who died in ignition-related crashes of GM cars. Although the investigations are continuing, it appears that at least one GM engineer may have lied under oath about the matter.
This story has heroes and villains, although most engineering ethics cases are not black and white, including this one. Consulting engineer Hood and GM CEO Barra appear to have done the right things with what they learned. Investigations may prove that the GM engineers involved with the faulty ignition switch may have made the best decisions they could have, based on the information they had available. No automaker can afford to do as much prototype testing as they would like. It took making and selling thousands of cars to reveal that a few people with exceptionally heavy keyrings could end up getting killed by a switch that took just a little less torque than usual.
But the truly blameworthy actions happened after GM began receiving reports of such ignition-caused crashes. One fatal accident due to a defect that can occur under certain conditions should be looked into, and if necessary, a recall—not just a service advisory, which GM issued about the matter in 2005—should be issued.
This situation shows that corporations, like people, have good times and some not so good times. GM’s financial troubles possibly dissuaded decision-makers from issuing the massive recall that would have been needed to fix the ignition defect early, before more defective cars were sold. But the result has been an even larger and more costly recall later. Let’s hope GM can fix all of the defective ignitions soon and move on, a sadder but wiser organization.
Sources: I referred to the Wikipedia article “2014 General Motors recall,” as well as the following online news articles. CNN reported on the problem at http://money.cnn.com/2014/04/02/news/companies/gm-recall-part/. Engineer Mark Hood’s detective work is described at http://www.bendbulletin.com/home/1949311-151/a-florida-engineer-cracked-gms-ignition-flaw#. Also, a Reuters article at http://www.reuters.com/article/2014/03/31/us-gm-recall-congress-idUSBREA2T0HO20140331 correctly describes the critical component as a “detent” plunger (it has been elsewhere described incorrectly as an “indent” plunger). And National Public Radio published a helpful timeline of the issue at
This column originally appeared on the Engineering Ethics blog, you can find it by visiting http://engineeringethicsblog.blogspot.com/.