Vehicle Electrification - April 18, 2013 - 3

How safe is
safe enough?

Ad Index
TE Connectivity cover
dSPACE Inc
7

Resource
Links
Sales Force
Contact Us
Archives
SAE Board of Directors
SAE Membership
SAE International Vehicle Electrification,®
April 18, 2013, Volume 4, Number 2.
SAE International Vehicle Electrification
(ISSN 2159-4279) is published 6 times
a year by SAE International.® SAE
International is not responsible for
the accuracy of information in the
editorial, articles, and advertising
sections of this publication. Readers
should independently evaluate the
accuracy of any statement in the
editorial, articles, and advertising
sections of this publication that are
important to him/her and rely on
his/her independent evaluation.
For permission to use content in
other media, contact copyright@sae.
org. To purchase reprints, contact
advertising@sae.org. Copyright ©
2013 by SAE International. The SAE
International Vehicle Electrification
title and logo are registered in the
U.S. Patent and Trademark Office,
and feature articles are indexed
and included in the SAE Digital
Library. For additional information,
free demos are available at www.
saedigitallibrary.org.

That question moved to the front of
my mind as I was putting together
an article on the Boeing 787 battery
problem (see page 6), which as of
this writing was nearing full resolution.
Mike Sinnett, Boeing Vice
President of Engineering and Chief
Technology Officer, 787 Program, at
a technical briefing on March 15
said the company’s engineers had
put in more than 200,000 hours to
understand the battery problem and
come up with a fix—and presumably many more hours since that
date. He didn’t say how many engineer-hours were spent designing
the battery system in the first place.
Some might conclude that however much time Boeing spent on
initial battery design, it wasn’t
enough. That would be a somewhat
natural—if not necessarily accurate—supposition. A National
Transportation Safety Board hearing scheduled for April 23-24 on the
787 battery situation promises to
shed light on the sufficiency of the
company’s engineering effort.
It’s worth noting, though, that regardless of how many hours Boeing
spent on initial battery design, the
FAA signed off on it. Indeed, the
NTSB as part of its investigation is
trying to determine whether the
FAA’s certification process was rigorous enough.

SAE Vehicle Electrification evsae.com

Foreword

Patrick Ponticel SAE Associate Editor

Boeing could have spent more
time than it did on initial battery design and testing. The same could
be said of any company that ever
produced any product that ever
failed in any way. If safety were everything, the FAA would make
Boeing put its new steel battery enclosure inside another even stronger enclosure that in turn would be
housed in a still stronger one, and
on and on. And NHTSA would limit
the speed limit of cars to 25 mph,
even on highways.
But we don’t pursue such impractical measures even though
lives—however few—may be
saved. In the battery case, it might
even be that secondary and tertiary
enclosures would come with unintended consequences that offset
whatever safety advantages were
envisioned. In such a case, more
safety could be less safety.
As engineers well know, everything is a trade-off—safety included. More safety comes at a cost
and means either less of something
else or higher overall product cost.
With the law of diminishing returns
in mind, they at some point must
declare, “this much safety is
enough.” That’s not a critique;
they’re just doing their jobs.
It should be better appreciated
how extremely complex and difficult
the “enough” call is for engineers.

http://www.sae.org/events/sales/Magazines/09salesreps.pdf http://www.sae.org/magazines/contact.htm http://www.sae.org/mags/aem/digital.htm http://www.sae.org/about/board/list/ http://www.sae.org/membership/ http://www.evsae.com

Vehicle Electrification - April 18, 2013

Table of Contents for the Digital Edition of Vehicle Electrification - April 18, 2013