Photos of the Titan sub's wreckage support the theory that the carbon-fiber hull failed first, expert says

• Glimpses of the wrecked Titan submersible wreckage were seen as its remains were brought ashore.
• These provide clues to what may have happened while a formal investigation is underway.

Photos of the Titan submersible wreckage support the theory that the vessel's carbon-fiber hull led to its catastrophic implosion, an expert told Insider.

The US Coast Guard brought ashore debris from the Titan submersible this week, giving a brief imperfect glimpse as it was taken away for analysis.

Jasper Graham-Jones, associate professor in Mechanical & Marine Engineering at Plymouth University, analyzed footage and photos for Insider.

Though it is impossible to be conclusive from these pictures alone, he said the most likely scenario was that the carbon-fiber hull gave way under the enormous pressure of the ocean depths.

Another possibility is that the ship's small front viewport gave way.

Here's why, picture by picture.

1. The titanium structural rings are intact

The picture above, recorded by Canada's CBC News, shows structural titanium rings that supported the structure of the submersible. They are intact and therefore do not seem to have failed.

OceanGate Expeditions' controversial Titan submersible is thought to have imploded within hours of its descent towards the Titanic wreckage on June 18. The five passengers onboard the submersible are presumed dead.

A forensic investigation is underway to determine the exact sequence of events, and will run an exhaustive analysis on the remains to build a conclusive picture. In the meantime, photos, the Titan's own history, and expert opinion gives us something to go on.

OceanGate's design of the submersible received heavy criticism over the years, especially for its use of a carbon fiber composite hull.

Most submersibles are made out of titanium, and many deep-sea experts told OceanGate they were wary about using carbon fiber, which is not as strong.

The Titan's design featured two titanium rings bound to the carbon fiber hull. The rings seem to have held firm, Graham-Jones said.

"It shows that titanium was the right material to use, and linking with the composite was possibly the wrong material to use," he said.

2. The front viewport of the ship seems to have failed

The picture, captured by CBC News, shows debris that seems to be the front viewport of the ship. There is nothing in the porthole anymore other than the red cable being used to lift it.

While Graham-Jones said that it wasn't impossible that the salvage operation removed the acrylic viewport to make room for the red cable, he said it wasn't likely.

"They could have lifted it in a bag," without tampering with it, he noted.

"It looks to me like it's failed, the window's gone," he said.

OceanGate's choice of front view window was also questioned before the disaster.

David Lochridge, OceanGate's former director of marine operations, alleged in August 2018 court filings that the company installed a front viewport certified to a depth of only some 4,200 feet (1,300 meters) — far less deep than the Titanic wreckage it was built to visit.

It's not clear whether the design changed between 2018 and its final mission — but it makes clear that the viewport was a cause for worry from the start.

An unresolved question, said Graham-Jones, is whether the window failed first, or whether another part failed and the viewport got blown out during the implosion.

3. No large slabs of the hull seem to have been recovered

Graham-Jones said the most telling part of the footage was what you couldn't see: there were no big slabs of the carbon-fiber hull.

The investigators recovered large fragments of the covering of the ship, a material that was placed above the carbon fiber hull, pictured above. But they don't seem to have found much of the carbon fiber hull itself.

It could be that these components happened not to be visible in the images and footage.

But for Graham-Jones, it is a sign the composite carbon-fiber hull likely failed first.

According to him, both the window failing and the hull failing would have led to the implosion of the ship. But if the front viewport had gone first, the pressure would have been slightly less intense on the hull, so "would probably see bigger pieces of composite there."

A possibility, he said, is that the carbon fiber failed because repeated trips had stressed the material, making small cracks that eventually gave way. This would also explain why the Titan made trips before without incident.

If such a failure did take place, Graham-Jones said, you would expect "lots of small bits of composite carbon fiber," consistent with the absence of large chunks in the imagery.

4. Also no fragments of carbon fiber attached to other debris

The picture above, Graham-Jones said, shows tubes and piping that would have been inside the ship. These were encased in a metal cage that would have been bound to the carbon fiber hull.

"The joint should be strong enough that it goes into the carbon, and so you'd have carbon left on that piece," in many scenarios, said Graham-Jones.

But it doesn't seem like that happened. The absence of visible carbon fiber on the joints could mean one of two things.

Maybe the joint failed. Graham-Jones said the joining is generally done with epoxy glue, which needs to be applied in a dust-free environment. Improper application could lead to problems.

But for Graham-Jones, it is probably more proof that the carbon-fiber hull went first, breaking into such tiny pieces you wouldn't see the remnants on the joints.

Investigators are figuring out the real answer — but slowly

Given the information at hand, the most plausible scenario is that the hull failed first, Graham-Jones said.

Investigators will now be taking a close look at the remains of the ship to determine exactly what happened.

They'll be "effectively looking under a microscope, at all the parts. And that would actually give you an idea of how it's failed," said Graham-Jones. On Friday officials in the US said they would report back in one to two years.