Tourist submersible visiting the Titanic is missing Part 2 68

[SWComposites]

The photo is of a piece trimmed off the end of the fabricated cylinder.

I think it was oven cured; typical of a lot of filament wound cylinders.

 

[Brian Malone]

Concerning this document in the Coast Guard investigation files:

Some of you appear to have figured out who is in the discussion, and I think have a grasp of part of it but the title of the document, and the redactions, and transcription errors leave me somewhat baffled.

1. This appears to be a transcription of a recording of a phone discussion between David Lochridge, Stockton Rush, and maybe Tony Nissen, and two other unknown OceanGate personnel? The title says "Interview" but that is a misnomer. The conversation is from January 2018 so presumably before OceanGate fired David. Stockton Rush pretty well just bulldozed every aspect of the report David presented, and the other attendees don't seem to support David's position in any manner or the transcription is not clear to me. ,
2. There are surprising typos in the document with homophones I would not expect in a 'court reporting transcription' - I have not seen many, so maybe this normal.
3. Any clue on is this from a phone recording? OceanGate recorded all office meetings?
4. Stockton Rush seems highly confident of the data and analysis for his belief of the safety of the hull yet says he won't provide data and analysis for review or he uses some type of obsfucation to deny access, but none of the other attendees seem to push back. Very odd review/discussion dynamic for the report David submitted and rather calmly defended.

 

[Brian Malone]

I find the dynamic indicated to be odd for the presumably technical attendees not seem to have access to the analysis Stockton said he had, and no one but David asked to review the data. So, were the others in agreement with Stockton? Were they just numbed to questioning Stockton's logic and passion? I have seen that dynamic before with a strong-willed CEO, so I get it slightly. But there seemed to be a definite one-sidedness to the interactions of the attendees.

 

[IRstuff]

I find the dynamic indicated to be odd for the presumably technical attendees not seem to have access to the analysis Stockton said he had, and no one but David asked to review the data. So, were the others in agreement with Stockton?

It would seem to be wholly consistent with Lockridge's assertiona that everyone else either sucked up to Rush or were kowtowing to Rush. Also, Lochridge has asserted that OG basically hired babes in the woods to do engineering, so Rush's ego wouldn't get bruised, presumably, and only he would hold sway over the design, design process, fabrication, and validation.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

[DirteJoe]

Could be wrong here, but I don't believe Rush had access to a lot of what he was claiming to. It seems to me he had blind trust in the whole thing because the Navy had good results with an old CF hull sub test bed they later retired, and his design was basically a modified version of what they did. Had access to public research docs, but thats about it.

Their dive/maintenance log also paints a picture of inexperience, multiple collisions, and bad hulls. First hull failed after 4 dives and was only caught because the rino lining was being redone. 2nd hull, among other issues, a loud band was heard when surfacing from the 4th dive, and seems no documented instances of inspection exist. That was right around the time OG was hurting for money and were delaying things time and time again.

 

[IRstuff]

It seems to me he had blind trust in the whole thing because the Navy had good results with an old CF hull sub test bed they later retired, and his design was basically a modified version of what they did. Had access to public research docs, but thats about it.

That's machts nichts; he REFUSED to test ANYTHING to validate his approach. Ronald Reagan already laid down what should be done, "Trust, but verify."

Rush deliberatedly hired inexperienced staff, even though he had tons of experts offering to help, but he rejected all of them because they all wanted testing to be done.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

[DirteJoe]

Testing did get done, just the bare minimum to satisfy what Rush wanted, and no more. Failures of carbon domes is what led him to titanium domes as well as what led to the idea of acoustically monitoring it for cracking. Being told they would have heard the failure creeping up on the 1/3rd scale had they been listening and not just using strain sensors cemented his thinking that they'd hear it before it is too late.

Testing the full size to failure is the only thing they didn't do unmannned.

Rushing the build and blocking inspections most likely meant he knew there were issues, just wanted to hide them and let those who don't know any better cover it up. Is full NDT of 5" thick carbon fiber even possible?

Not that I don't think full destructive testing needed to be done and CF was a poor material choice, but there's a wholye lot more to the failure than just that.
Poorly documented modifications to critical structures, a series of collisions, dropped and sanded viewports, and assembly issues before dives so bad that the front dome fell off. The maintenance history of that sub paints an interesting picture of both hulls.

 

[TugboatEng]

None of those things contributed to this failure. A CF failure would have pinched the structure in the middle. The domes were intact so they didn't fail. A viewport failure would not have crushed the CF tube. It is apparent that the sub failed at the connection between the CF tube and Ti dome. The sub had made several dives to depths so the joint was strong enough. The question now is what caused it to weaken?

 

[3DDave]

A fundamental CF failure would have been in the middle. A localized failure would have produced torn metal on both the rings in an asymmetric manner, not just on the rear.

Ideally the adhesive joint should not have been the place where the failure initiated but I think the underlying problem was a design failure to have an elastic match between the titanium dome and the carbon fiber to eliminate the shear and local bending load on that adhesive joint.

 

[TugboatEng]

The joint survived a few dives. I think it was several years old when it failed. We saw the video of the joint assembly. The surface was as machined. I doubt the dome went straight from the lathe to assembly. That means titanium oxide formed on the surface. That means the joint was sensitive to hydration. Hydration is a time sensitive failure mode.

 

[SwinnyGG]

It is apparent that the sub failed at the connection between the CF tube and Ti dome

Not so fast... It's not nearly that simple.

Any failure would result in water filling the passenger space at supersonic speeds - effectively a gigantic water hammer - which would be difficult to model and would break all sorts of things.

The adhesive joint as initial failure point is certainly one of the likely possibilities, but we don't know that yet to a certainty.

 

[TugboatEng]

The fact that the entire hull of the submarine was packed into one dome indicates that the failure initiated on the opposite end.

You're right to not make assumptions. I'm just frustrated because I saw the errors made in the adhesive joint a year ago in the advertising video.

 

[DirteJoe]

Tug, the ring setting video we saw was of the first dome that was discarded in 2019/2020. A new hull was installed in house reusing the original rings and components with an even worse adhesive job.

The frame/skids were also bolted directly to the hull with steel fasteners. Many impacts to the front skids from hitting bottom, launch deck, and crane mishaps on support boats that lead to skids bending and bolts working their way out of the carbon fiber. . I'm sure drilling into the hull

 

[SWComposites]

The frame/skids were also bolted directly to the hull with steel fasteners. > where did you find this info? if they drilled holes into the composite hull then they were really stupid.

 

[IRstuff]

The fact that the entire hull of the submarine was packed into one dome indicates that the failure initiated on the opposite end.

It's not obvious how much of the hull was packed into the back; there was a large piece of internal structure, the platform that passengers sat on that would have survived the implosion.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

[Brian Malone]

I understand the 'Interview' document a little better now: this is David Lochridge defending his inspection report to Stockton Rush and three other OceanGate employees after the major disagreement on safety of the Titan submersible. The January 2018 date of the interview matches with the claims in the whistle-blower litigation:

https://www.documentcloud.org/documents/23854184-oceangate-v-david-lochridge

So Stockton's antagonistic demeanor and the silence of the other OceanGate technical team is understandable now - this meeting wasn't a technical review. David Lochridge was already out the door at OceanGate, or soon to be.

 

[DirteJoe]

SWComposits, I had read it in the maintenance and repair log posted by the USCG in some liks above. I'm away from my PC, but I'll look through it agaín real quick and try to copy and paste some of that info.

Edit:
Direct link to log:

https://media.defense.gov/2024/Sep/...EANGATE DIVE AND MAINTENANCE LOG_REDACTED.PDF

Mobile screenshot of mention of Hull to frame fastening via bolts.

Thread inserts into the hull. (This was the old hull just around when they found the crack and a month before it was decided to replace it. Modification was likely carried over to the new hull)

Dives and dive notes are the top few pages. Repair logs are below. Dates, dive numbers, etc available to cross reference damage with dives, dive depths, and dive locations.
The closer you look to some of the photos they've released in their shop you can indeed see they've used fasteners to attach directly to the hull, as well as some other modifications that have been done to the hull and domes.

I'm sure more detailed drawings/photos exist but those are not public at the moment.

In the lower portion on the interior of the hulls, they had also drilled for and installed strain and acoustic sensors. Some were surface moint, but one photo of their monitoring system was released during assembly that does show sensors mounted into the hull

Edit 2: Attached document of maint log.

https://files.engineering.com/getfi...EANGATE_DIVE_AND_MAINTENANCE_LOG_REDACTED.pdf

 

[3DDave]

The fact that the entire hull of the submarine was packed into one dome indicates that the failure initiated on the opposite end.

I don't think it was. There was a substantial structure beneath the floor to hold the high-pressure air tanks. It's about the same size as the material shown in the photo. Even Rush would appreciate the problems that the tanks would cause if they were loose and the sub rolled onto its side with him in it.

I don't believe anything was bolted to the carbon fiber nor any holes drilled into it. AFAIK mounting was only to the titanium rings or the domes.

I need to hit the Submit Post faster to avoid being overtaken.

 

[drwebb]

Brian Malone: Agreed. In my scanning of the 'Interview' document I think I recall the phrase "exit interview" somewhere. With redactions it's hard to keep up with who may be saying what (other than Rush), but I gathered someone from HR called a final meeting to try and stave off Lochridge's dismissal. And the purpose of the recording was CYA for OG to justify cause for the firing. There's a detailed rehashing of the technical disagreement (with a lot of Rush rationalizing his technical bases for dismissing Lochridge's concerns- consciously 'for the record' in tone), and at the end Lochridge(?) agrees there's no 'path forward' for him with the organization, which would be a key outcome for HR's files. If it was an HR meeting that could color the technical team's participation because they were presumably included only to clarify the circumstances surrounding the Rush/Lochridge dispute rather than adjudicate it in that forum.

What struck me is Rush's conviction he had designed around ANY possibility for catastrophic failure modes, along with his utter contempt for conventional subject matter expertise. So the hubris of Rush met its nemesis in the similarly unsinkable Titanic- if this story appeared as a modern techno-Greek-tragedy the critics would probably dismiss it as far-fetched or derivative.

 

[Brian Malone]

drwebb - yes, the confidence and conviction Stockton Rush had for the hull safety and design /testing method(s) is on one hand admirable: he is all-in with the design and believes in it and is the principal pilot of the vehicle, but on the other hand: this is tragic due to the known failure and loss of life of Stockton and those on board who trusted the vehicle and Stockton. Definitely a reminder that engineering requires confidence and some level of swagger but when faced with multiple inputs for caution maybe a step back for reassessment is warranted.