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
http://www.npr.org/2014/03/31/297158876/timeline-a-history-of-gms-ignition-switch-defect.
But the publicity surrounding the lawsuit attracted enough attention that others with similar crash incidents on their hands began looking into the matter
ReplyDelete