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Posted on:
04/01/2001
Read the theory
below - then reflect upon CI-611
(the China
Airlines 747-200's high altitude breakup)
|
Engineer has alternate theory on plane
disaster
By
Gary Stoller, USA Today
|
| Boiler expert links jet's age, design to why roof ripped
off |
The Aloha Airlines
jet descended for landing on Maui, Hawaii, and passenger Matt Austin
had noticed the luggage racks rattling and swaying when the thrust
reversers came on.
It didn't startle him. He had seen that happen before on other
older Aloha jets. But Austin remembered the name painted across
the plane's exterior: Queen Lili'uokalani. It was a 19-year-old
Boeing 737.
A week later--on April 28, 1988--the same jet's roof ripped
open 24,000 feet over the Pacific Ocean, killing one flight
attendant and seriously injuring seven passengers and a crew
member. Austin counted himself lucky. Aloha Flight 243's last
flight didn't really begin to grip him until the next year, when
the National Transportation Safety Board issued its accident
report.
This is a detective story. It's about a mystery that aviation
professionals say was solved 12 years ago and the persistence of
Austin, a former Hawaii boiler inspector, who has spent all those
years and $45,000 of his money trying to prove that the experts
got it wrong.
It's also about an accident that forever changed maintenance
practices for old planes and about an alternative theory that
could have far-reaching consequences. Finally, it's about the
intriguing possible parallels between boiler safety and airplane
safety.
But first it helps to know something about Austin. A mechanical
engineer, Austin has no professional expertise in airplane
accidents. He is an expert on boilers; the NTSB consulted him
about a train boiler explosion in Gettysburg, Pa. Austin, 43, runs
a consulting business,
Hawaiian Steam Engineering, which designs, inspects and
restores boilers and locomotives. He also consults for the U.S.
Navy on servicing nuclear submarine power plant components.
Since 1989, Austin has researched the Aloha accident
independently, always maintaining that his only motivation is
"engineering truth" and a conviction that sharing his insights can
prevent similar accidents. He has a Web site,
www.disastercity.com, where he details his theories on the Aloha
accident and other disasters.
If Austin's theories are correct, a design that is intended to
prevent catastrophic failures on nearly all Boeing jets could be
flawed. It may even pose a danger to passengers,
Austin says. Boeing says the design meets FAA requirements and
works as intended.
Austin also says his study has convinced him that:
- Old jets are not safe to fly, even if all required
maintenance has been done.
- The FAA's aging aircraft program, which requires airlines to
repair and inspect old jets, should be scrapped. The program
allows planes to fly beyond their design life and relies on
airline inspectors who may not detect all structural problems,
he says.
To reach those conclusions, Austin purchased and pored over
more than 4,000 pages of NTSB accident findings. He attended a
course for airline maintenance managers on aging aircraft and
studied books for aeronautical engineers. He bought special
computers to study the NTSB's photos of the accident and related
forensic evidence.
Austin also corresponded with NTSB investigators, FAA officials
and a Boeing engineer. The investigators stand by the NTSB's
conclusions but say they respect Austin's engineering knowledge.
"In every accident I ever worked, all kinds of crazies came out
of the woodwork with theories about what happened,'' says former
NTSB investigator Brian Richardson, who led the NTSB group that
studied why the Aloha jet broke apart. ''Matt Austin is not one of
those people. He has good, solid credentials, and he's not going
off the deep end.''
The NTSB says it will not reopen the accident investigation,
but Richardson says the FAA should study Austin's theory. Then
goes a major step further.
''Matt may well have nailed the cause of the accident,'' he
says. ''I don't really know.''
|
|
An important accident
Aloha Flight 243 was
bound from Hilo to Honolulu when its roof tore off. An emergency
landing was made in Maui.
Many aviation experts consider the flight the most significant
accident in commercial aviation. It showed how inadequate airline
maintenance procedures and poor FAA oversight can result in
tragedy, and it prompted an FAA program to more vigilantly inspect
aging airplanes.
The NTSB, which investigated the Aloha accident, concluded the
jet's roof and walls tore off in flight because multiple fatigue
cracks existed in the jet's skin.
Those cracks developed, the NTSB said, because lap joints that
were supposed to hold the fuselage together became corroded and
failed. A lap joint connects two overlapping metal sheets of the
fuselage.
The role of lap joints on the Aloha plane is what first
captured Austin's attention. He read a story about lap-joint
failure in the accident and realized the same words had been
written about a boiler explosion in Brockton, Mass., in 1905.
|
|
The boiler connection
The danger of failed
lap joints is well known in the boiler industry, which stopped
using them on large boilers in the 1920s. In Brockton, a shoe
factory boiler explosion collapsed a building, killing 58 people
and injuring 117 others.
When a boiler's lap joint fails, a hole opens in the boiler's
shell. The water inside instantly turns to steam, and increased
pressure causes an explosion. Such a phenomenon is known as a
fluid hammer, which Austin says caused the Aloha accident.
If Austin's theory is correct, it solves a question that the
accident's investigators asked: Why didn't Boeing's ''fail-safe''
design, which is supposed to prevent a massive breakup, work?
Boeing says the 737 was designed to decompress safely with as
much as a 40-inch crack in the plane's skin, the 0.036-inch thick,
aluminum outer layer of the fuselage. Instead of an explosive
decompression, the hole in the skin is supposed to release
internal pressure in a controlled way. In the Aloha accident,
investigators concluded that more damage occurred--about 18 feet
of the fuselage tore away--because many fatigue-caused cracks had
gone undetected.
Austin says that a weakened fuselage was not the main reason
for the extensive damage.
A 10-inch-by-10-inch hole opened, he says, in the roof of the
front cabin at a location known as body station 500. (Body
stations are identifying points on the fuselage that are measured
in inches from near the nose of the jet to the rear.) A powerful
stream of air swept an Aloha flight attendant off her feet and
toward the hole, Austin says. Her head and right arm went through
the hole, he says, but her body momentarily plugged it, creating a
jolt of pressure that ripped the jet apart. The flight attendant
was swept out and her body was not recovered.
''Slamming the door on a 700-mile-per-hour jet stream creates a
localized, short-duration high-pressure spike, up to several
orders of magnitude (greater than) the allowable design
pressure,'' Austin says. ''This is a fluid hammer.''
Forensic evidence, Austin says, shows where the flight
attendant's skull struck the exterior of the plane. The location
of the skull print is consistent with the location of a plugged
hole at body station 500, he says.
The NTSB's official accident report says, however, that the
breakup of the jet began about 5 feet farther forward, at about
body station 440.
But Richardson, the former NTSB investigator, says Austin
pinpointed a mistake in the NTSB's report. He says he always
assumed the breakup began close to the point that Austin says.
The wreckage that could reveal where the breakup occurred is at
the bottom of the Pacific Ocean.
|
|
NTSB not persuaded
USA TODAY brought
Austin's analysis to NTSB Chairman James Hall, who joined the
board 5 years after the Aloha accident and recently announced his
resignation. He said Austin's theory makes sense, but the NTSB
doesn't believe it happened that way.
''We don't disagree with Mr. Austin's explanation about how an
airplane can decompress at 24,000 feet after a 10-inch-by-10-inch
hole is blown open in the skin and about how devastating the
'fluid hammer' effect can be at this altitude,'' Hall said in a
letter. ''We disagree, however, with his conjecture involving the
role the flight attendant's body played.
''The roof of the Aloha airplane came off as a result of
multiple site damage --mainly, small fatigue cracks that emanated
from many chamfered rivet holes. These cracks joined together,
resulting in the catastrophic separation of the skin.''
Austin agrees that the many fatigue cracks weakened the
structure, but he says the plane wouldn't have ripped apart if the
hole hadn't been plugged. And, Austin adds, ''The NTSB validated
my fluid-hammer theory. They couldn't say anything more without
reconvening a pool of experts and reopening the investigation.''
Richardson says he never heard of the fluid-hammer theory until
Austin explained it. No one on his structural team, he says, ever
mentioned it during the course of the investigation.
He says, though, he'll stand behind his and the NTSB's
conclusions. ''We never thought that the hole in the fuselage
remained small enough long enough for anything to plug it and
produce the kind of pressure spike that is common to the pressure
vessels that you are familiar with,'' Richardson wrote Austin.
Austin says, however, that the difference between the NTSB's
findings and his analysis is, ''We're 60 inches and probably 20
thousandths of a second apart.''
He says he enlarged NTSB photos of the skull print, used a
computer to view them from a different angle and pinpointed the
skull print's exact location. ''The skull print is the key,''
Austin says. ''It wouldn't be there so graphically if the flight
attendant didn't plug the hole. If there would have been an
out-rush of air without a hole being plugged, her whole body would
have been sucked out at once away from the aircraft.''
Austin also corresponded with FAA officials in 1998. He was
told that the FAA intended to do studies on his theory, but the
agency later said it couldn't do the work because Congress had cut
the FAA's research budget. King Frey, a retired aeronautical
engineer who worked for two aircraft manufacturers, Hughes and
Douglas, and for Northrop Grumman, which makes fuselages for 747s,
buys the fluid-hammer theory.
''Matt's reasoning and logic are right on target, and he has an
excellent probable theory that should be researched,'' Frey says.
The odds are very small that such a phenomenon will occur, Frey
says, ''but rare things do happen.''
As 737s get older, however, it raises the possibility from an
astronomically small number to a number that should be taken
seriously, Frey says. The increased possibility of a fluid-hammer
effect, he says, needs to be heeded by Boeing and airline
mechanics.
Regardless of whether he's right about the Aloha accident, he
questions whether a plane can be designed for a safe decompression
when a fuselage tears open. That would cause a powerful stream of
air to escape from the cabin, he says, which could sweep up
persons or objects not belted down, shatter eardrums and cause
more serious injuries.
''Safe decompression is a fly-it-'til-it-breaks philosophy,''
he says. ''It's stupid to have a design concept that says a plane
is OK until it blows a hole at 24,000 feet.''
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Boeing defends design against theory
Boeing officials say
their design is sound and meets FAA regulations. Further, the
company says, it tested the plane for the theory that Austin has.
Boeing's Jack McGuire says computer simulations were done in 1965
to test what would happen if a 40-inch hole--one much larger than
the hole that Austin believes popped open on the Aloha plane--was
plugged. The tests showed that cabin pressure is maintained
longer, increasing passengers' chances of survival, he says.
Richardson says research is needed to study Boeing's
safe-decompression design.
''I think it's worth determining if this type of scenario
should be a design consideration in the future,'' says Richardson,
who is now an airline pilot. ''Testing by the FAA/manufacturer is
the only way to determine if it can happen in an aircraft, absent
funding by some private source. The FAA should spearhead the
effort to see if Boeing's fail-safe design is viable.''
FAA officials in Washington did not respond to written
questions about safe-decompression design and aging aircraft.
Richardson and some other aviation experts believe the FAA
should study the fluid-hammer phenomenon.
''Matt's efforts and goals are commendable,'' he says. ''The
industry needs to be constantly reminded of the past so it can be
ever vigilant in the future.''
That's Austin's credo. ''Disasters keep recurring because we
don't learn from those that have struck in the past,'' he says.
''History is repeating itself before our eyes.''
|
Copyright 2001, USA TODAY. Reprinted with
Permission. from
this linkand
for the whole 9 yards:
http://www.disastercity.com/
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