Original subtitles

A sound cuts through the cabin. The passengers glance around, uneasy, but

nothing. So the noise is ignored, and the countdown to disaster is triggered.

The North Sea is harsh, unpredictable, and deadly.

In winter, waves can rise over 15 meters, about as tall as a five -story

building. Wind gusts have reached more than 87 knots, the force of a Category 2

hurricane. Water temperatures stay just above freezing, making the odds of

survival in any type of accident quite low.

But beneath these dangerous waters lie vast oil and gas deposits, which means

companies will send men to harness that energy.

for a profit in the 1970s platforms like brent delta and 40s alpha were built to

access those deposits each platform holding hundreds of workers engineers

support crews each platform houses its own small community about 54 nautical

miles from shore but getting people there was hard ships were slow and at

mercy of rough seas sometimes taking more than a day to travel a distance

would take less than an hour by road. The expense of a ship to ferry the

workers, multiplied by the number of workers in transit, adds up to a

significant amount of lost time and money.

Helicopters changed everything.

They could carry people, cargo and emergency teams crossing over 100

miles of open water in just over an hour. They became essential for fast

changes that boats couldn't handle efficiently.

By the 1980s and 1990s, helicopters were the offshore industry's lifeline,

making tens of thousands of flights each year from Stavanger and Bergen in

Norway and Aberdeen in Scotland.

A common helicopter in use was the Eurocopter AS332 Super Puma.

It's a medium -sized utility model with four blades and two engines.

built for two crew and 18 passengers in the early 2000s many oil companies

banned the use of the middle rear seat which cut capacity to 17 passengers they

found it was too difficult to evacuate three passengers through the back window

in an emergency the as332 later evolved into the ec225 model

with a five bladed rotor and more engine power but kept the same main rotor

gearbox The EC225 Super Puma was a twin -engine medium -sized helicopter,

longer and more modern than the original AS332.

It carried two crew and 19 passengers with four -point safety belts and high

back seats to support the head and neck during a crash.

On the 1st of April 2009, Bond Offshore Helicopter Flight 85N was set to make

several trips from Aberdeen to oil platforms in the North Sea.

The original AS332 Super Puma had just returned from the Bruce platform.

With its rotors still turning, the crew changed over.

The new pilot received a brief, the aircraft was refueled and passengers

boarding. At 10 .42 the helicopter took off for the BP Miller oil field about

145 nautical miles northeast of Aberdeen. The flight was uneventful.

But 10 minutes before landing, the passengers heard a strange noise.

They didn't think it was serious, so no one told the crew.

At 11 .49, the helicopter landed on the BP platform.

With the rotor still spinning, the passengers disembarked, the aircraft was

refueled, and 14 new passengers boarded for the return flight to Aberdeen. The

weather was good, with light south -to -southeasterly winds, clear skies, and a

few broken clouds between.

Flying conditions were smooth and the sea was calm.

At 12 .03 the helicopter took off and climbed to 610 meters on its return to

Aberdeen. At 12 .54 the co -pilot made a routine call to report 14 passengers on

board, the helicopter in good condition and an estimated arrival time at 13 .14.

12 seconds later, the pilot sent a mayday call, followed by the co -pilot

repeating the mayday with details about their location.

The helicopter briefly climbed to 670 meters, then turned right and began a

rapid descent.

A crew member on the vessel Norman Aurora saw the helicopter drop sharply

hit the sea about two nautical miles away from their location.

The four main rotor blades and hub separated and fell into the water

An explosion followed, sending grey smoke into the air that soon turned

The crew member raised the alarm and Aurora turned toward the crash site

11 nautical miles northeast of Peterhead, Scotland.

The Norman Aurora launched a fast rescue boat as it headed toward the crash

site. At Aberdeen, the radar controller confirmed the mayday and tried to reach

the flight crew.

He asked another helicopter on a similar route to check the sea where flight H5N

had last appeared on radar.

Both the rescue boat and the helicopter reached an area of disturbed water about

150 metres wide.

They found debris from the helicopter, two life rafts and eight people wearing

survival gear.

No survivors.

Search and rescue teams reached the site within 40 minutes and recovered

floating debris.

On the evening of the 2nd of April, a survey vessel working for the Maritime

Coast Guard Agency scanned the seabed with high -definition sonar. The next

it located the main wreckage at a depth of 100 metres.

Fuselage, main rotor and tail boom.

Because of the depth, the Aircraft Accidents Investigation Bureau hired a

saturation diving recovery vessel to bring it up. On the 4th of April, a

support vessel arrived on site.

By the next day, all eight remaining bodies were recovered from the fuselage.

The flight data recorder and cockpit voice recorder were also retrieved and

to the Aircraft Accident Investigation Bureau in Farnborough, along with the

wreckage for analysis.

Investigators from the UK Air Accident Investigation Branch focused quickly on

the main rotor gearbox.

The rotor head had torn free from the fuselage.

The engines were intact and the controls hadn't failed.

Something inside the gearbox had broken apart with force too great for the

structure to survive.

A helicopter's engines spin fast, but the rotors must actually turn more

than the engine.

The Super Puma's twin engines run at 23 ,000 revolutions per minute.

but the main rotor turns at about 265 revolutions per minute. The main rotor

gearbox reduces the engine speed by about 87 times while transferring

of horsepower to the rotor mast.

It has two sections.

The lower section, called the main module, cuts the input speed to about

revolutions per minute.

Above it sits the epicyclic reduction gearbox which reduces it further to

265 revolutions per minute.

Inside the upper module is the second stage planetary gear system.

A central sun gear drives several planet gears that spin inside a ring gear.

As the sun gear turns, the planets orbit and share the load evenly, spreading

out the enormous forces.

In the Super Puma, these planet gears take some of the heaviest stress in the

aircraft, each handling power in tens of thousands of horsepower.

They spin for hours under heavy loads, and if one fails, the result can be

catastrophic. To detect problems early, the gearbox has magnetic chip detectors

that collect metal debris in the oil.

If a gear or bearing begins to wear, the detectors sense the metal filings and

trigger a warning.

In theory this allows engineers to find and fix issues before a failure happens

in flight.

Inside the damaged epicyclic module investigators found a second stage

gear with its rim split open.

Microscopic analysis showed curved lines on the fracture surface proving a

fatigue crack had grown slowly through the steel.

A tiny flaw formed deep inside the gear, spreading slightly with each rotation

until it finally reached the rim, which caused the whole system to fail.

When the rim broke, the gear shattered, sending steel fragments into nearby

components and jamming the gearbox.

The engines kept turning, forcing power into the jammed system until the weakest

link, the connection between the rotor head and the fuselage, snapped.

tearing the rotor apart.

Investigators then found something more concerning.

36 flight hours before the crash, a chip detector had picked up microscopic

metal fragments just a few millimeters wide.

Maintenance engineers examined them, but because procedures for interpreting

chip debris were unclear, they simply cleaned the detector and returned the

helicopter to service.

No one recognized that those metal particles came from the planet gear rim.

An early warning of a hidden crack.

The Aircraft Accidents Investigation Bureau concluded that the second stage

Planet Gear failure caused the crash.

The fatigue crack had developed slowly, releasing fragments that hinted at a

serious fault.

But without clear guidance, the warning went unnoticed.

In the months after the crash, the Aircraft Accidents Investigation Bureau

issued urgent safety recommendations.

Helicopter operators were told to treat every fragment from chip detectors as a

serious warning.

New procedures were created to improve how metal debris was analyzed.

The message was clear.

Metallic debris in the gearbox isn't routine.

It can signal a catastrophic failure already in progress.

The industry acted quickly.

European regulators temporarily grounded the Super Puma L2 fleet.

Flight operators Bond Offshore, CHC and Bristow carried out detailed inspections

of their helicopters.

Airbus helicopters released new service bulletins, redesigned components,

upgraded chip detection systems and assured operators that the risk was

understood and reduced.

By 2010, in less than a year, the Super Puma fleet was cleared to fly again.

The helicopters returned to service over the North Sea.

carrying hundreds of workers daily, and confidence in the fleet slowly returned.

Today, there are industries that support the safety of the men and women who

work offshore.

Part of that safety training is SUIT, or helicopter underwater escape training,

which all offshore workers must complete.

A helicopter body is lowered into the water and spun upside down to simulate a

water crash landing, and trainees must escape.

The passengers and crew on board the Super Puma didn't really have a chance

escape in the water, and the next story is no different.

On the 29th of April 2016, seven years after flight 85N, a CHC helicopter

service aircraft lifted off in the Norwegian sector of the North Sea.

CHC operated flights for Stas Oil ASA, now Equinor, including routes from

Airport, Sledlund, to the Gullfax oilfield.

The helicopter, an Airbus EC225LP Super Puma, a newer version of the

same family as Flight 85N, was operating as Flight 241.

That morning, the crew had already completed one round trip to the Gullfax

platform and returned to Sledlund. At 10 .05, they departed again for Gullfax B.

After landing on the platform, the road was kept spinning as passengers

disembarked and 11 new ones boarded. The turnaround lasted 12 minutes.

At 11 .16, flight 241 took off for its return to Sledlands, climbing to 900

meters with the co -pilot in control.

The helicopter cruised at 900 meters until reaching the coastline, then

descended to 610 meters after clearance from air traffic control, flying at 140

knots. Moments later, engine speed dropped sharply.

The main rotor tilted erratically. There was metallic screeching, then a loud

bang. The rotor separated completely and the helicopter began to fall in a

ballistic arc.

People on the ground over a mile away heard the metallic noise and looked up

see the helicopter falling without its rotor.

Some nearby witnesses saw paths breaking away.

Eight divers preparing to dive at Turoi Key heard the noise.

Two had helmet cameras that recorded the event.

Without its rotor, the helicopter rolled right almost a full turn, yawed to the

right, then rolled left as the nose dropped vertically.

At about 11 .55, it struck the small island of Sorokitilman near Turoi in

Oigarden municipality, killing all 13 people instantly.

The impact destroyed the helicopter and most wreckage slid into the sea, resting

a few meters offshore at a depth of about five meters.

A white cloud of fuel vapor rose and ignited, starting a fire on the island.

Wreckage, fuel, and oil spread across land and sea.

The detached main rotor flew separately, landing at Toskora Island less than

half a mile north of the main crash site.

At 11 .57, a surveillance aircraft spotted smoke over the area and

crash. Air traffic services immediately notified the Joint Rescue Coordination

Center for Southern Norway.

At 12 .01, six minutes after impact, rescuers began to arrive.

A rigid inflatable boat reached the crash site first, followed a minute

two smaller boats.

The Sotro Fire Department arrived with three vehicles and six personnel.

Two firefighters were taken to the small island, but found that life -saving

efforts were impossible.

Soon after, additional responders from Oygaarden and Bergen fire department

arrived, joined by police, Norwegian armed forces, air ambulance crews, and

civil defense units.

At 13 .05, the first diver entered the water.

Recovery efforts began immediately after the crash.

Within 24 hours, the cockpit voice recorder and flight data recorder were

retrieved from the sea. On the 30th of April 2016 the main wreckage was lifted

from the water and the detached main rotor was recovered from Suscora Island.

Parts of the main gearbox including two pieces of a fractured second stage

planet gear were found.

Debris from the helicopter was spread across 180 ,000 square meters.

Some key gearbox components and attachments were missing, prompting an

land and sea search.

Norwegian civil defense teams scanned the shore with metal detectors while

divers from the Bergen fire department and the Navy searched grid sections of

the seabed. A remotely operated vehicle and a one meter wide fledge fitted with

14 magnetic arms were used to sweep the seabed. By September 2016 the organized

search ended.

Most gearbox parts had been recovered.

but the second stage planet gear carrier and forward suspension bar were still

missing. With the agreement of the Norwegian Accidents Investigation Board,

accident site became a training site for the Naval Diving School.

In February 2017, during one of these training dives, the missing second stage

planet carrier was finally found.

Investigators from the Norwegian Accidents Investigation Board, supported

UK Aircraft Accidents Investigation Bureau and Airbus Helicopters, examined

wreckage. Inside the gearbox, they found the second stage planet gear shattered

in almost exactly the same way as the 2009 accident.

Microscopic analysis showed the same failure pattern. A fatigue crack started

from a tiny flaw inside the rim, and slowly expanded until the rim split

When it failed, fragments destroyed nearby gears, causing the rotor to

from the helicopter.

After flight 241's crash, engineers and investigators were left asking how a

gearbox could fail so completely without warning.

To find out, they studied how fatigue fractures form and why they're so hard

detect inside a helicopter gearbox.

The second stage planet gear in a Super Puma is roughly the size of a dinner

plate made from ultra -hard steel and weighing several kilograms.

Every time the rope returns, its feet mesh correctly with others, transmitting

thousands of horsepower 265 times a minute, millions of times over its

Inside the steel, stress is enormous.

Though the gear looks solid, it's made of microscopic crystals with tiny flaws.

Over time, these flaws concentrate stress, forming cracks hidden beneath

surface. The cracks grow invisibly and don't release fragments until they reach

the surface, often just before total failure.

This means the problem isn't missing a warning. It's a failure with no warning

at all.

Chip detectors, the main safety system, only work when fragments circulate in

the gearbox oil. If the crack stays internal there's nothing to detect until

it's too late.

Even then chip detectors have limits. They're small magnetic plugs just a few

centimeters long that only attract particles passing close by.

Oil moves unpredictably through the gearbox so not all debris reaches the

detector and tiny cracks might not release fragments at all.

For flight 241, investigators determined the gear failed internally without

releasing debris, completely bypassing the only available warning system.

Helicopter gearboxes are both vital and fragile.

They take on extreme forces with no backup.

When they fail, the aircraft simply falls out of the sky.

In 2009 the warning was missed.

In 2016 there was no warning.

Both ended the same way.

The rotors were free and lives were lost within seconds.

In the months after the crash, European regulators grounded all EC225 and

AS332 Super Puma helicopters.

Offshore workers refused to fly in them, even staging protests and calling the

aircraft coffins with rotors.

Airbus helicopters worked to regain confidence by redesigning gears,

monitoring systems, and introducing stricter inspection procedures.

They put the failure down to a rare manufacturing flaw that had been fixed.

Oil workers weren't convinced.

In the UK and Norway, the unions demanded that Super Pumas were taken out

service. By 2017, major operators like Bristow and CHP confirmed they would

discontinue the EC225 for the North Sea service.

That decision ended the Super Puma's role in the region.

They still fly in other parts of the world, but in the UK and Norway, the

Super Puma is linked with tragedy and loss.