AviationBanter - View Single Post

**[email protected]**

On Thu, 28 Feb 2013 02:51:15 +0000 (UTC), (Bradley K.
Sherman) wrote:

|
| Boeing Co. and the Japanese company that makes lithium-ion
| batteries for Boeing's 787 Dreamliner are at odds over what
| should be included in the final package of fixes intended
| to get the jets back in the air, according to government
| and industry officials familiar with the details.
|
| GS Yuasa Corp. has told the Federal Aviation Administration
| that while it supports engineering and design changes
| Boeing has proposed to try to end the six-week-old
| grounding of 787s, it believes the proposed package is
| inadequate to mitigate all potential 787 battery hazards,
| the officials said.
| ...
| Yuasa's primary argument, according to the officials, was
| that its own laboratory tests strongly suggest that an
| external power surge--or another problem originating
| outside the eight cells of the battery--kicked off the
| sequence of events on the 787s that experienced burning
| batteries. Yuasa told the FAA that temperatures and current
| fluctuations recorded on those planes weren't consistent
| with short-circuits originating inside its batteries.
|
| As a result, Yuasa is urging the FAA to require
| installation of a sophisticated voltage regulator intended
| to prevent current from flowing into 787 batteries at the
| first sign of a problem. Boeing's package of proposed
| battery enhancements doesn't add such a feature to existing
| safeguards, people familiar with it say. Boeing is arguing
| that its overall package--which includes sturdier and
| better separated cells and a new fireproof container around
| the batteries--is adequate to prevent any internal or
| external malfunctions from causing fire or smoke.
| ...
| In congressional testimony Wednesday, FAA chief Michael
| Huerta said he expects to receive an internal agency report
| on the proposed fixes next week, but he didn't indicate
| when he expects to act on them.
| ...
http://online.wsj.com/article/SB10001424127887323293704578330480004073900.html

--bks
Typical McDonnell Douglas military thinking - don't avoid (solve) the
problem, contain (hide) it.

They have not found the cause of the problem yet. SOMETHING caused
the batteries to overheat. I'm still betting it's outside the battery
system itself. The Dreamliner is a hodgepodge of outsourced
assemblies designed by third world engineers - which in itself is not
necessarily a problem - but the whole final product needs better than
average engineers to make sure all the subassemblied are designed to
work with each other - and to ensure that the thing is properly
assembled. I still think the battery pack itself is OK. I also think
the APU is OK - but I strongly supect there is an issue with the
interface between the two. An issue which, when it is finally found,
will, in hindsight, be just a "minor tweek" in the grand scheme of
things.