All language subtitles for Mayday.S07E01.Scratching.the.Surface.1080p.AMZN.WEB-DL.DD+2.0.H.264-playWEB_track3_[eng]

639 pieces of wreckage
are recovered from the scene.

Six hundred
and thirty-nine pieces

that only deepen the mystery
of a deadly plane crash.

All right,
a little bit more
to the right. There!

But when investigators
bring up the 648th piece
of China Airlines Flight 611,

they get their answer.

There was definitely
a eureka moment on the dock.

It would
be scrutinized more closely
than any other piece of debris.

On this single piece
of wreckage,

investigators would find
the one clue
that would tell them

why a modern jetliner
with 225 people on board
shattered in mid-air.

Mayday! Mayday!

Thirty feet.

Speed is low, sir, watch it.

Did you feel that?

May the 25th, 2002.

Gears up.

A China Airlines 747
lifts off from Taiwan's capital,
Taipei.

Taipei approach,
Dynasty 611 airborne
passing 1,600.

Dynasty 611,
Taipei approach radar

contact climb
and maintain
flight level 260.

Two, six, zero.
Dynasty 611.

Autopilot B, engage.

China Airlines
is Taiwan's national airline.

There are 225 people on board
Flight 611.

Today's flight is a short one.

One hour and 40 minutes
across the Taiwan Strait
to Hong Kong.

This route is one of the most
widely-traveled on the planet.

It makes so much money,

it's called The Golden Route.

Ladies and gentlemen,
the fasten seatbelt sign

has been turned off.

For your safety,
we do recommend
that you keep

your seatbelt fastened
at all times while seated.

Minutes after taking off,

Flight 611 climbed steadily
above the Taiwan Strait.

The plane's autopilot
controls the ascent.

And, then, 20 minutes
after taking off,

at an altitude
of almost 35,000 feet...

At Taipei Area Control,
the flight vanishes from radar.

Dynasty 611, Taipei.
Dynasty 611, Taipei.

I've got a plane off radar.

China Airlines 611.

It's last known
return was East 119
decimal 67,

North 23,
decimal 98.

Taiwanese authorities
quickly launch one of
the largest rescue missions

in that country's
aviation history.

I gave
a clear order that the priority

would be searching
for whoever was still alive.

Then bodies, and then,
only then, wreckage.

More than
1,000 people take part.

Fishing boats, the Coast Guard,
and Taiwan's military
race out to sea.

Flight 611 was 55 kilometers
from the Taiwanese shore,

just north of the Penghu Islands
when it disappeared.

Rescuers find debris
floating in the Taiwan Strait.

The first thing
we saw

was a great amount
of wreckage,

including landing gear wheels,
napkins, knives, and forks.

Wreckage from the plane
is spread far and wide.

Some items are found on land
more than 100 kilometers
away in central Taiwan.

As the rescue effort continues,
Taiwan's Aviation Safety Council

begins its investigation
into the crash
of the 22-year-old plane.

747-200,
delivered August 2nd, 1979.

Kay Yong
is the managing director
of the ASC.

He'll be leading
the investigation.

We're setting up
a command post
on Penghu Island. Let's go.

China Airlines have had
a very, very poor
safety record.

As a matter of fact,
it was considered
one of the worst in the world.

Typically, it had, like,
one major accident
every four years.

This particular investigation
was, by far,
the most difficult one.

And one of the reasons why
was it's...
it's in the ocean floor.

The search
for survivors goes on
around the clock.

There were 225 people
on the airplane.

Nobody is found alive.

The bodies are taken
to the Penghu Islands
to be identified and examined.

Since the accident involved
an American-made plane,

the NTSB
joins the investigation.

A team of investigators
is dispatched to Taiwan,

They'll be led by John DeLisi
in Washington.

We have a very good
working relationship
with the ASC,

The Aviation Safety Council,
of Taiwan.

So we knew that
they would ask for

and welcome our assistance
in the investigation.

Wreckage that's found floating

is also brought
to the Penghu Islands.

Investigators need to know
how one of the world's
most successful planes,

on one of the world's
most-traveled routes,
simply fell out of the sky.

Well, Boeing 747
is the world's most popular
jumbo jet,

and it's flown
millions of people,
probably billions of miles.

So it...
We were very concerned.

Good morning. I'm anxious
to see what you have.

Sophisticated ground based-radar

tracked Flight 611
throughout its short journey.

It should provide investigators
with a much clearer picture
of the flight

than the radar
at Air Traffic Control.

Kay Yong gets the first
major clue in this case.

The radar tracked the plane
as it climbed on course
to 35,000 feet.

Then, suddenly,
Flight 611's signals
split apart.

The break up
is quite graphic.

Right when the event happened,
it appeared as if there were

three or four sizable pieces
of wreckage that were getting
radar returns

that then began to drift
and scatter as they fell
to the earth.

So that told us
that the airplane
broke up in flight.

Investigators now
must turn their attention

to finding out what caused
that breakup.

There's all kinds
of theories about,

you know,
what seems to be happening
on that particular aircraft.

We knew that something
massive had happened,

happened suddenly
without warning.

It doesn't take long
for the media to consider
a sinister possibility,

that Flight 611 was shot down.

- China and Taiwan
have a combative relationship.
-

China has fired missiles
towards Taiwan in the past.

There's suspicion in the media
that China shot down
Flight 611.

There were a lot of theories
about, you know, the...

It was shooting down
by enemy fire.

Only eight months earlier,
a Siberia Airlines flight

with 78 people on board
was shot down
over the Black Sea.

It was accidentally hit
by a missile fired from Ukraine
during a training exercise.

On the day
of the China Airlines crash,

China was conducting
military exercises
in the Taiwan Strait.

But officials there insist
no missile was launched
towards Flight 611.

None of the wreckage
recovered so far

has any of the telltale signs
of being hit.

And there's no evidence on radar
that there was ever a missile
heading for Flight 611.

Once the evidence
began to come in,

it very quickly ruled out
a missile,

much the same way
that it ruled out
it being a mid-air collision.

There were no other objects
in the air near the airplane.

Few things
would cause a plane
to break up in mid-air.

One of the big ones
is a bomb.

Medical examiners
check the bodies
that have been recovered

for burn marks
and shrapnel.

They find none.

The plane's metal skin
would be torn and curled
in a very particular way

if there had been
a bomb on board.

Investigators find
no such damage
on any of the pieces.

But to rule out a bomb,
they'll have to find
more wreckage.

I think that'll be it
for floating wreckage.

The team from the NTSB
arrives in Taiwan.

Good morning.
I'm Clint Crookshanks
from the NTSB.

Good to see you, gentlemen.
I'm afraid we still
don't have much.

Clint Crookshanks
is a structural engineer
who knows the 747 intimately.

I didn't have
any preconceived notions.

This was
my first major accident
working for the NTSB.

We are not getting much
from the floating debris.

In flight break-up,
that's all we know.

Taiwan's Civil
Aeronautics Authority
doesn't take any chances.

They ground all
of China Airlines'
747-200 series planes

until they can be inspected
for mechanical flaws.

This puts added pressure
on investigators
to find out what happened.

Thank you for bringing these.

To the NTSB,
this accident seems
to have a lot in common

with one of the world's
most-studied plane crashes.

That of TWA Flight 800
six years earlier.

Like the China Airlines flight,
it broke into pieces
while still climbing.

That plane crashed
into the Atlantic

shortly after taking off
from New York.

TWA Flight 800
was the biggest investigation
the NTSB has ever done.

Lasted about four years.

The painstaking
investigation uncovered
a design flaw with the 747.

Wiring near one of the plane's
fuel tanks

could spark and ignite the fuel
in the tank.

Investigators conclude

that's what likely
caused the crash.

Investigators are struck
by similarities
between the two flights.

Both were 747s.

Both disintegrated
without warning
while still climbing.

Both flights took off
in very hot weather.

The heat may have caused
Flight 800 to explode.

That plane sat on the tarmac
with its air-conditioning
running.

Investigators believe hot air
from the air conditioner
overheated the plane's fuel.

The early evidence is pointing
to a repeat of TWA Flight 800.

So it looks really
very, very similar.

So, therefore, the...
our immediate focus

was, essentially,
the central fuel tank.

Three weeks
after the crash,
the Jan Steen,

a sophisticated salvage vessel,
arrives in the Taiwan Strait.

It's equipped with divers,
a diving chamber,

and a remote-operated submarine
complete with sonar
and video cameras.

The NTSB were tasked with
manning the recovery vessel

and watching video screens
from the ROV.

Using sonar,

investigators have located
the wreckage of Flight 611
deep underwater.

All right,
to the right a bit.

Clint Crookshanks
knows all the pieces
that make up a 747.

But he's never seen them
like this.

It was really quite a shock
when I first saw pieces
on the floor of the ocean.

With only the lighting
of the ROV to guide you,

you would notice something
that looked like
an airplane part.

The ROV would then circle around
the part, looking at it
from all angles.

Crookshanks' job
is to help the Taiwanese

identify specific airplane parts
among the wreckage.

I think it takes
a different kind of mind

to be able to look
at a mangled part

and kind of straighten it out
in your head

to really determine
where it comes from
on the airplane.

All right, a little bit more
to the right.

All right, go back.

There! Okay, that's definitely
a piece of wing. Let's mark it.

Once a piece
is identified,

its GPS coordinates
get recorded.

The GPS mapping
tells investigators

that the debris is spread out
over 325 square kilometers.

It will be difficult
to track down
specific pieces of the plane.

Twenty-five days
after the crash
of Flight 611,

the plane's two black boxes
have been found.

One contains voice recordings
of conversations in the cockpit.

The other, data from
the plane's flight computer.

Either could hold the clues
that will reveal what happened

during the final minutes
of the flight.

If the answer is on the tape,
investigators may not have to
bring up

more wreckage
to the surface.

The data is critical.

Everybody ready?

Investigators begin
with the plane's cockpit
voice recorder.

They hope that the pilots
will have said something
to each other

about an emergency on board.

Welcome aboard China Airlines.

The recording begins
about 10 minutes
before the plane took off.

- Twenty.
- Preparations
for the flight sound normal.

- Okay, after start checklist.
- After start, anti-ice.

The crew
checks all their systems

and runs through
standard checklists.

Off. Off.

It was a very,
very experienced crew.

Both the captain and the fli...
and the first officers
were quite seasoned.

Dynasty 611, runway 06,

wind 050
at nine are cleared
for take-off.

Cleared for takeoff.
Dynasty 611.

Take off.

- 80.
- Check.

Vee one.

Rotate.

- CO-PILOT: [ON RADIO] Flap five.
One-one green.

CO-PILOT: Okay, flap up.

Investigators listen
to more than conversations.

They also want to hear
if the plane itself
was making any unusual sounds.

Noises on the cockpit
voice recorder can either
be audible spoken words

that are recorded
by a microphone,

or they can be
structural discrepancies
that are picked up

by the microphone.

If anything, though,
this cockpit is unusually quiet.

Uni Air 608,
reduce speed...

The captain
seems relaxed.

The microphones
pick up the sound
of controllers

talking to other planes.

Trans Asia 536
fly heading 050.

In the moments
before the disaster,
nothing seems wrong.

There are no unusual sounds.

Now descend
and maintain 250.

The final words
spoken in the cockpit
are from Captain Yi Ching-Fung.

Two thousand.

He calls out
the distance
to their cruising altitude.

That's followed
by the sound of a chime...

...alerting the crew
that they are
nearing 35,000 feet.

And then the cockpit microphone
picks up the sound of the plane
breaking apart.

Half a second later,
the recording stops.

The cockpit voice recorder
indicated that the...

the conversation
of the cockpit crew
were totally normal,

and all of a sudden, just...
just dying.

The recorders told us
that something happened,

but it wasn't enough to tell us
exactly what it was yet.

Many things had been ruled out
by then, but we didn't have
the golden nugget.

We didn't have
the real piece of evidence

that told us what initiated
the breakup of the 747.

After the disappointment
of the voice recorder,

studying the wreckage
becomes the only option
for investigators.

They focus their efforts
on items that can either

prove or disprove
the link to TWA Flight 800.

So we play a lot of focus
on the wreckage observation,

examination of the center
fuel tank.

On July the 12th,
48 days after the crash...

Okay, whoa, whoa.

Little to the left, please.

Success.

All right.

That's definitely
the central fuel tank.

Okay, let's mark that.
Let's bring that up.

The tank joins
the sea of wreckage
piling up at the pier.

Investigators study it closely
for any evidence
that it exploded.

If it did explode
like the TWA tank,
it would be curled and twisted.

And the metal
would be bent outwards.

But this fuel tank
is different.

And we found
the central field tank
was relatively intact.

And it's crumpled inwards.

Unlike the tank
from the TWA flight,
there's no soot.

There would be
if the jet fuel inside
had ignited.

So, at that time,
we pretty much ruled out

it was the cause
of the center fuel tank.

The wreckage
recovered so far
has also forced investigators

to abandon another theory,

that a bomb brought down
the plane.

None of the wreckage
showed any evidence
of sooting,

any kind of explosive damage.

The China Airlines
crash was neither a repeat
of TWA Flight 800,

nor a deliberate bombing.

Investigators are running
out of leads.

As more wreckage
is identified and recovered,

investigators find
an intriguing clue.

It's discovered
when they examine a series
of small vents from Flight 611.

All commercial jetliners
have dozens of these vents
near the floor.

They're essentially
pressure release valves.

They're called dado panels,

and there's only one reason
for them to open.

If the cargo area
underneath the passengers

were to suddenly decompress,
the pressurized air above

would exert so much force
on the floor

that it could collapse
and damage
vital fight controls.

That's precisely what happened
to a Turkish Airlines flight
in 1974.

The pilots couldn't
control their plane
after their cargo door blew out.

We've lost it!

If the floor
on that flight
hadn't collapsed,

the pilots may have been
able to save the plane.

After that accident,
the NTSB recommended

that manufacturers
install many more relief vents

between a passenger plane's
upper and lower levels.

If there is decompression
in the cargo area,

the dado panels
open automatically

and release the pressure
on the floor.

There were 65 dado panels
on the China Airlines flight.

Nineteen of them
were recovered
from the ocean.

Four recovered panels
were in the open position.

It tells investigators
that there must have been

a sudden loss of pressure
beneath the passenger cabin.

But it doesn't tell them
what caused it.

The dado panels
lead investigators closer

to solving the mystery
of this crash.

But it's just a small piece
of a much bigger puzzle.

There are hundreds of pieces
of wreckage to be examined
for clues.

Kay Yong now wonders
if a few of those pieces

might be able to tell him
where the decompression
originated.

I've been reading about
the trajectory analysis
you did on Flight 800.

I'd like to try it.

Ballistic trajectory analysis
is a technique

that US investigators used
to figure out how TWA Flight 800
disintegrated.

It's impossible to do
without specialized computers.

We figured that,
because it disintegrated
in the mid-air,

the ballistic analysis
from which they,

NTSB, did in TWA 800
could be very, very useful
to us,

to help us to analyze
the trajectory
of the flying debris.

The analysis
is based on a simple fact.

The pieces that came off
the plane first would be
the first to hit the water.

If investigators can figure out
which pieces those were,

they'll know
where the trouble began.

Radar that had been tracking
the plane as it climbed

also ended up tracking pieces
of debris as they fell.

The salvage workers
have recorded
the precise location

of those same pieces
of wreckage.

Their logs could match
a specific piece
to its radar track.

Investigators know
the wind speed
on the day of the crash,

and they can obtain
precise information
about ocean currents.

The last piece of the puzzle
comes from the plane's
flight data recorder.

The plane's altitude, speed,
and direction at the time
of the break-up.

As they're
brought to the dock,

every single piece of wreckage
has been logged and numbered
for identification.

Three-two-seven.

Kay Yong
selects 18 pieces of wreckage
for the computer analysis.

Some from the front,
some from the middle,

and some
from the back of the plane.

One-nine-nine.

Along with
all the other data,
he'll feed information

about each item's weight
and shape into the computer.

Five-two-six.

Based on where
the pieces fell, the computer
should be able to calculate

which of those 18 pieces
was the first
to come off the plane.

Can we see when each one
of those items
separated from the aircraft?

All of the data
paints a telling picture
of what happened at 35,000 feet.

Kay Yong gets to see
how Flight 611 broke up
from beginning to end.

The tail came off first.

Along with
the dado panels,
it's a very important clue.

So that pretty much indicating
that something happened
in the back of the aircraft,

rather than something
happened in the forward part.

Investigators are now keen to recover items
from the rear of the plane.

Hundreds of pieces of wreckage
are piling up at the pier
on the Penghu Islands.

The NTSB sends
metallurgist Frank Zakar

to Taiwan to examine
the wreckage.

I was walking along the yard
where the wreckage was placed,

and, at that time,
I walked up to item 640.

I noticed that there were some
peculiar areas of interest

that I wanted
to look at
a little bit further.

With this
battered piece of metal,
investigators have struck gold.

There was definitely
a eureka moment on the dock

that was, hey,
we might have something here.

Hey, it's Frank.
I think we found
your golden nugget.

Item number 640
would give investigators

a revealing glimpse
into the past,

and lead them to conclude
that the crash of Flight 611

actually began
22 years earlier.

Let's get as many pictures
as we can.

The massive piece
of fuselage that has caught
Frank Zakar's attention

is exactly what investigators
have been searching for.

It includes a piece
of the belly, the side wall,
and the rear cargo door.

It's from
the back of the plane,

precisely where the analysis
told them the break-up
had begun.

This piece of wreckage
was highly unusual.

It wasn't what we were seeing
on all the other pieces.

And it immediately
drew our attention,

and drew the focus
of the investigation.

The way
most of the metal is torn

suggests it ripped apart
violently in mid-air.

Aerodynamically,
as an airplane's
moving through the air,

if it's... if it were
to break apart,

just the force
of the incoming air
at over 500 miles per hour

will just break up
perfectly good structure.

That's what we call
an overload fracture.

So most of the pieces
that came up early

were just indicative
of that kind of overload.

When metal breaks
due to overload or overstress,
it comes apart at an angle.

But the fractured edges
of piece number 640
aren't angled,

they're flat.

What do you think?

It's definitely not overstress.
It's metal fatigue.

Fatigue fractures
happen when metal is stressed

repeatedly over time
until it breaks.

It looks very different
from a stress fracture.

Typically,
a metal fatigue crack
will have a flat appearance.

It'll be very smooth.

That's exactly
the kind of crack

that investigators observe
on piece number 640.

That tells them
it didn't break off
the plane suddenly

as it fell from the sky.

This piece separated
from the plane over time.

Had it caused the deaths
of 225 people?

There was much more work
that needed to be done.

A detailed analysis
of the piece
had to be done

in order to see
if this, in fact,
was the smoking gun.

There's something else about
this piece that stands out.

It has a metal patch on it.

It's called a doubler plate.

It's the equivalent of a patch
on a punctured tire.

It's not unusual
to find numerous doubler plates
on older planes like this one.

A doubler plate is like a patch
that you put over fuselage skin.

If there were
to be a tear,

or a blemish,
a crack identified,

you'd want to repair
the fuselage
back to its original strength.

And one way to do that
is to put a doubler plate,

or a patch right over
the existing structure.

At some point,
this section of the 747
had been repaired.

Investigators need to know
why it was fixed
and how that was done.

We're looking for repair
to the aft lower lobe.

Whatever it was, it was big.

Investigators sift through 22 years
of documents.

But the records are sketchy.

Finding details
on one particular repair
could take time.

There's something about
this particular doubler

that catches
Frank Zakar's attention.

The outside of the fuselage
contained longitudinal streaks

that appeared to emanate
from between the doubler plate
and the skin.

Something is leaking
from underneath the metal patch.

Was there a possibility
that the skin had broken, cracked?

And was there any fuel or air
coming out from between
the doubler and the fuselage?

And that warranted
further examination.

Let's cut it from here...

to here.

And send this piece
to Chung-Shan.

In order to see
what's underneath the doubler,

a large section of piece 640
is sent to a lab.

No evidence has been found
of structural
or mechanical problems

with Boeing's
747-200 airplanes.

Taiwanese aviation officials
have no reason to keep
the planes on the ground.

The Chung-Shan Institute
of Science and Technology
is a military research facility.

It's at the forefront
of Taiwan's space program.

This is where investigators
take a section
of piece number 640

for a closer examination.

The NTSB's Frank Zakar
finds a telling clue
on the crack itself.

When I looked
at the fracture surface,

I found
that this one specific area
was covered with aluminum oxide,

pretty much similar
to rust on a car.

Years of exposure
to oxygen changes
the color of metal.

The discoloration
tells investigators
that this particular crack

at the rear of the airplane
has been there
for a very long time.

Then, when the doubler
is finally removed,

investigators get a look
at the aluminum skin underneath.

They're intrigued
by what they see.

When we disassembled
the doubler plate
from the skin,

we noticed that there was
some fairly long gouge marks.

This is beyond
the kind of damage
a doubler is meant to patch.

That was an "aha" moment,
that we... we might have
something here.

The search
of the plane's documents
also pays off.

The records contain
a very short reference
to a mishap 22 years earlier,

when this plane
was only six months old.

Speed is low sir, watch it.

Its tail
scraped the runway
while landing.

- Did you feel that?
- It happens
when a plane

lands or takes off
at too steep an angle.

It's called a tail strike.

Dynasty 009,
Hong Kong tower.

We observed smoke and sparks
from your tail on landing.

Roger, Hong Kong Tower.
We'll have that looked at.

Tail strike, sir.
I better log that.

It is a relatively
common occurrence.
It's not a good thing.

Some airplanes even have
what's called a bumper
in that portion of the fuselage,

so that if the tail
ever does get too close
to the ground,

instead of sacrificing skin
from the fuselage,

you might have
the sacrificial bumper
that will take that wear.

Tail strike damage
is routinely repaired.

Investigators want to know
how China Airlines
went about fixing the plane.

They could only find
a brief mention of the repairs

that were done
in the plane's logbook.

That's all there is?

That's all we could find.

There's not
a lot of detail
in China Airlines' records.

China Airline indicating
they could not find any...
any of those documents.

And when we start
looking for it,
we could not find any.

And then they said
that they probably got lost.

The documents
that do exist show that the day
after the tail strike,

- China Airlines
did a temporary repair.
-

Workers attached
a large aluminum plate
over the damaged area.

What do we know about
the permanent repair?

Doesn't get much better.

A more
permanent repair was to be
carried out within four months.

This is what we've got.

The maintenance
records indicated

that the permanent repair
was done

in accordance
with Boeing recommendations

in their Structural
Repair Manual.

Evidence that we uncovered
indicate that the repair
was not done

per the Boeing
repair manual.

According to the manual,

many of the scratches
on the plane were too deep
to be repaired.

The entire damaged section
should have been cut out
and replaced.

You have to follow
certain procedures,

and that the Boeing
Structural Repair Manual

indicating very clearly
what you should do
step by step.

22 years later,

investigators can tell that,
for some reason,

the damaged piece
was not replaced.

The scratches
from the tail strike
are still there.

China Airlines engineers
tell investigators

that the scratched area
was too large to cut out,

so they sanded
the scratches down instead.

In the event
of scratching,

it depends on how deep
the scratches are.

If they're not very deep,
they can be blended out.

But if the scratches
are too deep,

the repair technique
that's called for

is to actually cut out
all of the scratched material

and then design
a doubler patch that's larger,
by a big percentage,

of the structure
that was originally removed.

The scratches
weren't sanded down,
or cut out.

They're still there.

Maintenance workers
then made one final mistake.

They put
the doubler plate right over
the scratched material.

The doubler plate
that they put on

was not 30 percent larger
than the affected area.

In fact, it was barely,
maybe not even
in certain locations,

larger than the area
that was scratched.

Even though
the repair wasn't done

according to Boeing's
instructions,

the way it was logged
made it seem like it was.

So, for 22 years,
anyone reading that entry
would assume the damaged area

had been cut out,
as it should have been.

Pieces were really
starting to fall into place now.

Once we saw
this piece of structure

- that had the fatigue cracks
in it...
-

...and we realized that it
came from a structural repair
that was not done properly...

...that was left to fly
for 20 years...

Airborne, passing 1,600.

...things began to make sense.

By covering
an improper repair
with a doubler,

and then documenting the repair
as meeting Boeing standards,

the workers made their mistake
impossible to detect.

What was so insidious
about this improper repair

was that the doubler plate
hid all of the damage.

So, if you weren't there,
watching them do
this repair improperly,

you wouldn't know
that it was done improperly.

You would have assumed
that the structure underneath

had been cut out
the way it was supposed to.

And every time
the plane took off
over the next 20 years,

the concealed problem
got worse and worse.

The air inside
a commercial airplane
is pressurized.

As the plane climbs,
air is forced into the cabin

to keep the pressure
inside the plane greater than
the pressure outside.

It's like inflating a tire.
The inside air pushes against
the plane's skin.

Each time
the airplane pressure rises,

pressure builds up
inside the fuselage
of the airplane.

That crack could open up

for a certain amount of inches
or microns or millimeters.

The plane's skin
expanded and contracted
a little bit every time.

Because they weren't
properly repaired,
the cracks grew and spread.

Eventually, the crack grew
into a stunning 2.3 meters.

If you were charting the crack,
you would have seen
very slow growth early.

But as time went on,
the growth was getting
bigger and bigger.

A small scratch
had grown into
an enormous problem.

Then, in May, 2002,
as Flight 611 climbed,

that problem killed
225 people.

As the airplane
climbed in altitude,
and the fuselage was pressured,

that put enough strain
on this growing crack

that it reached
its critical length.

And, from there,
it just spread
like a spider web.

It went in all directions,
and it probably looped
all the way around the fuselage

to the point where the entire
aft section of the airplane

just broke off
from the rest of the structure.

The plane
went into a steep dive.

The force of the air
on what was left of the plane
quickly ripped it to pieces.

Investigators know
that an unseen crack caused
Flight 611 to break apart.

They now discover
that China Airlines
came heartbreakingly close

to finding that crack
and saving 225 lives.

The China Airlines 747,
was in regular service
for 22 years

following the improper repair
to its skin.

It took off and landed
more than 20,000 times.

Over the years,
mechanics would have
scrutinized the plane.

There's regular inspections
per the Boeing
maintenance program

that have to be performed
on the airplane.

But the massive crack
forming at the rear of the plane
was never detected.

Another accident
in another country

almost led China Airlines
to discover the hidden damage.

In 1988, the roof peeled off
an aging Boeing 737
owned by Aloha Airlines.

As a result of that incident,

the Federal Aviation
Administration

laid out an inspection procedure
for older planes.

Airlines around the world
were forced to inspect
their planes

much more diligently
for corrosion and cracks.

The regulation
called for airlines

to re-evaluate
all existing repairs
to a plane's structure.

Indications on this airplane
were that if they had looked

at the maintenance records
and compared it to the repair,

they would have had
to remove the repair
and redo it.

China Airlines
took the first steps

of the new procedure in 2001,
a year before the accident.

The airline identified
and photographed

thirty-one different doublers
on the 747,

including the one
over the catastrophic crack.

Those pictures
show investigators

that China Airlines overlooked
a vital clue

that could have warned them
of the looming danger.

We examined the photographs
that China Airlines
took of the repair

and noticed
that there was some issues

that may have warranted
further investigation.

Investigators see a dark brown stain
on the outside of the plane.

It's the same
mysterious staining

that led Frank Zakar to suspect
there was a hole
behind the doubler

when he first saw it
on the pier.

So why hadn't this stain
raised alarms before the crash?

For years, passengers
on China Airlines' doomed 747
were allowed to smoke.

They filled the pressurized air
with nicotine.

The smoke was being forced out
through the crack
at the rear of the plane.

Over time, that smoke
left a nicotine stain
on the outside of the plane.

It was very vivid.

Any experienced
maintenance engineer

would be able to spot it
right immediately.

Smoking hadn't been allowed
on China Airlines

for seven years
before the crash.

It tells investigators
that the crack in the plane

had been there
for at least that long.

But instead of investigating
the source of the staining...

We need to conduct
the new inspection when we
do our next major check.

...China Airlines
scheduled the second part
of the FAA's procedure,

a detailed inspection
of the repaired areas.

And that would be
the 7-C check,

currently scheduled
for November the 2nd, 2002.

But the 747
never made it
to November 2nd, 2002.

It came apart
over the Taiwan Strait

five months
before the inspection

that would have, undoubtedly,
uncovered its hidden flaw.

Investigators want to prevent
a similar accident
from ever happening again.

They recommend
that aviation agencies
around the world

immediately inspect repairs
for any possible hidden damage.

We were no longer
gonna accept
just a quick write-up

that the repair
was done properly.

If the repair didn't have
all the necessary documentation

to allow us to know
it was done properly,

we were requiring operators
to take doubler plates off

and do a visual inspection
of the structure underneath.

The National Transportation
Safety Board

issues its own recommendations.

The board asks
that maintenance personnel

be warned of the consequences
of hiding the kind of damage

that could lead
to the structural failure
of an airplane.

The moral of this story
is that the repair
has to be done properly.

As a mechanic,
when you're doing work
on an airplane,

you're not thinking
about the people

who might be flying
on that fuselage
20 years from now.

But their safety depends on you
doing the repair properly.

China Airlines
has revised the way its fleet
is inspected and maintained.

Its safety record
has improved dramatically
since the crash of Flight 611.

Investigators also proposed
the development of new tools

that would allow mechanics
to detect damage
behind a doubler.

Such tools are being used today.

Boeing developed
a non-destructive procedure

that can find cracks
in the fuselage
underneath a doubler.

That device
uses ultrasound, sound waves
that travel through metal.

It can reveal damage
underneath a doubler.

It's the same technology
that allows doctors
to observe a fetus

while it's still inside
the womb.

The device would have been
able to detect

the crack behind
Flight 611's doubler plate.

But the technology
has some limitations.

A great number of hours
are required just to do

one specific area
of the airplane.

But the technology
is getting better.

The problems
that led to the China Airlines
disaster are not going away.

Planes the world over
are getting older.

And older planes need to be more
thoroughly inspected for cracks.

Six years
after the China Airlines crash,

Southwest Airlines
in the United States was hit
with a record-breaking fine.

$10.2 million
for missing inspections
designed to find cracks.

The fining of Southwest
brings back into focus

how important it is
to do maintenance properly
on an airplane.

A proper program
of maintenance and inspections
can be costly.

But, as China Airlines showed,

the price of not maintaining
aging planes is even costlier.