|Wiring likely cause of
Swissair crash - Boeing |
By Stephen Thorne / The Canadian Press
Renton, Wa. - An electrical problem was likely the main
contributor to the crash of a Swissair jet off Nova Scotia last
September, though other factors may have dealt the plane's final
blow, says Boeing's safety director.
Canadian investigators, working with industry and other safety
agency officials, have determined some wires on the MD-11 aircraft
were damaged from the inside out, not the outside in, Ron
Hinderberger said in an interview.
"Every indication is that the electrical system is the origin of
whatever occurred," he said this week. "Whether it was the reason
why it got so bad, we don't know."
Boeing's chief crash investigator shed new light on the Swissair
investigation and expressed confidence in the Canadians who are
running it. His comments:
- Investigators have found that heavy sooting and other
fire-related damage spread well into the plane's first-class
section, further than previously thought.
- Evidence suggests the co-pilot was at the controls while
pilot's seat was not in a flying position when the plane crashed.
- Boeing offered to inspect wiring in a suspect entertainment
system a California contractor installed in part of its fleet last
year, but Swissair turned them down and opted to take it out.
"They deactivated it," said Hinderberger. "Subsequent to their
deactivation, they decided to remove the wiring that was in the
front end of the airplane."
Swiss pilot Urs Zimmermann reported cockpit smoke about 20
minutes before his MD-11 jet went down off Peggy's Cove, N.S., last
Sept. 2. All 229 aboard were killed.
Key to the probe has been the question of whether wires in the
downed plane arced after fire damaged their insulation.
It now appears, however, that a wire-related problem such as an
electrical overload, or cracked and chafed insulation like that
found on other MD-11s caused the lethal, lightning-like jumps from
wire to wire. Fire is a likely result in either case.
"There are some wires in the forward part of the airplane that
have been identified as having been heated from the inside out,"
Hinderberger, who has had an investigator on the scene since the
investigation began, refused to say if the telltale wires were
original to the jet or if they were from the inflight entertainment
system. Both sets were damaged.
Investigators are confounded by the degree of heat damage and
scorching patterns in the ceiling just aft of the plane's cockpit
wall, he said.
"Electrical problems don't usually manifest themselves in that
much heat. So what occurred that generated as much heat as it did?"
The cockpit's emergency oxygen supply is located in the same
general area and could conceiveably have fed such a fire.
But Hinderberger said makers of the three oxygen bottles that
supplied the cockpit crew determined they were pressurized - "at
least partly full" - when the aircraft hit the water.
"If an oxygen line had severed, my feeling is those bottles would
have emptied pretty quickly."
Some experts believe a flashover - an explosive electrical fire -
occurred aboard the Swissair jet. Hinderberger said there has been
little talk of that among investigators.
There has been speculation that one or both pilots abandoned the
cockpit due to intense heat.
He said the copilot's seat was in the flying mode - in and
forward - and the stress on his belt indicated he was in his chair
when the plane hit the water. Zimmermann's seat was in the
But the position of the captain's track-mounted seat - away from
the control panel and off to one side - doesn't necessarily mean
Zimmermann bolted, said Hinderberger.
"It could have been for a number of reasons."
The pilot, Swissair's chief instructor, could have been reaching
to get a manual, or gotten up to get another manual and then gotten
back in his seat to read it while copilot Stefan Loew flew the
The investigation, he said, is "going to be a long road."
Yet Hinderberger says he's confident chief investigator Vic
Gerden and his team will find the main causes of the disaster.
"Based on the tenacity of the Transportation Safety Board of
Canada, I would say it's very likely," he said, adding the team is
analysing parts that most other investigative agencies would have
dismissed as irrelevant.