TOKYO--The head of a Japanese air safety organization looking
into battery problems on a Boeing 787 said Wednesday that the
investigators will expand the scope of their search to include the
jet's circuit wiring after finding part of its installation to be
"unusual."
The investigating team discovered that the circuit wiring of the
burned battery and another one were connected, even though this is
unusual in airplanes, Norihiro Goto, chairman of the Japan
Transport Safety Board said at a press conference.
He added that the JTSB has already notified Boeing and All
Nippon Airways Co. (9202.TO) of the finding and is seeking feedback
from the aircraft maker.
A major development in the slowly progressing probe is eagerly
sought by airlines around the world affected by the grounding of
all 50 Dreamliner jets worldwide, after battery problems caused a
fire on one plane and an emergency landing by another last month.
The carriers are waiting for the probe to determine the causes of
the incidents as soon as possible so that corrective action can be
implemented to get their planes back in the air.
"We have been investigating what happened, but as we haven't got
to a point where we can say why it happened yet, we can't say we've
made progress," Mr. Goto said.
He also stressed that the new finding has little to do with the
overheating, since the battery system has a diode module to block
any reverse current. As the JTSB has found nothing wrong with the
module, it is believed to have functioned normally, he said.
Still, the chairman said he is concerned there may be other
irregularly installed circuitry.
Masahiro Kudo, the JTSB's chief investigator said at a separate
briefing, that the unusual circuit wiring may have affected the
digital flight data recorder's measuring of voltage in the burned
battery. He added that if affected, the voltage of the battery
might have dropped to a lower level than shown by the flight
data.
A more accurate voltage reading could be crucial in helping the
JTSB make progress with its investigation, he added.
The batteries under investigation come from an ANA 787 forced to
make an emergency landing in western Japan on Jan. 16 with battery
trouble.
Write to Yoshio Takahashi at yoshio.takahashi@dowjones.com
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