On 3 April 2023, the Ministry of Defence submitted a letter to the House of Commons Defence Committee, providing details of the non-statutory investigation into the propulsion issues that affected HMS Prince of Wales.
The Minister of State, James Cartlidge, confirmed the conclusion of the investigation, which began after the ship suffered a starboard shaft coupling failure upon sailing from Portsmouth in August 2022.
The letter outlined that the investigation covered various aspects of the ship’s design, build, acceptance phases, and operations during Fleet time. The inquiry identified one causal factor as the misalignment of the starboard shaft from the build stage and the incorrect installation of key components. Several contributory factors led to this misalignment and the subsequent incorrect assessment of the starboard shaft and couplings’ performance.
“The causal factor identified in this instance was that PWLS starboard shaft was misaligned from build, and that the incorrect installation of key components resulted in the defect suffered.”
Sea Trials Reportedly Showed No Issues
According to the letter, during the ship’s sea trials, both shafts were extensively tested over several weeks and thousands of nautical miles. Vibration readings remained within limits at all times, and no issues, conditions of class, or actionable items were transferred into service from the Aircraft Carrier Alliance (ACA) to the Ministry of Defence (MOD) in 2019 at Vessel Acceptance.
“During PWLS’ sea trials, both shafts were extensively tested over several weeks and thousands of nautical miles in the Northern North Sea and UK South Coast Exercise Areas. Vibration readings remained within limits at all times. Accordingly, no issues, conditions of class or actionable items were transferred into service from the Aircraft Carrier Alliance (ACA) to the Ministry of Defence (MOD) in 2019 at Vessel Acceptance.”
Letter States Limited Operational Impact
The letter highlighted that following the August 2022 coupling failure, an alignment issue was also identified with the port shaft. Rectification work was initiated and is expected to be completed in time for the ship to commence her operational programme this autumn. It also mentioned that HMS Queen Elizabeth checked installation alignment readings, detecting no abnormalities. The operational impact of the defects on HMS Prince of Wales has been limited, with the Royal Navy delivering its Carrier commitments to NATO.
“The operational impact has been limited. HMS QNLZ undertook PWLS’s operational tasking from September to December 2022, after which she took over, as scheduled, as the Very High Readiness Strike Carrier. At all times the RN has delivered its Carrier commitments to NATO.”
Financial Cost and Future Actions Outlined in the Letter
The letter estimates the financial cost of the defect to be approximately £25 million. It notes that responsibility for payment has not yet been established and further comment on the matter would be inappropriate at this stage. The Department has reportedly conducted a preliminary examination of the investigation and the events that contributed to the defect, directing an urgent review.
“The financial cost is estimated to be approximately £25 million. Responsibility for payment has not yet been established therefore it would be inappropriate to comment further at this stage.”
Sounds very fishy – how can you have a misaligned shaft that operates within acceptable vibration limits. Who set the vibration limits?
Probably connected to those that are over seeing the constructing Ajax.
What I don’t quite get is that mis alignment problems were originally reported for the QE during trials and then we were told they were within acceptable limits. Just seems odd that if that were so that PofW still in build at that time wasn’t thoroughly checked to make sure there was any anomaly be it similar or new. One would expect such problems to be experienced in the first of class not the second especially if there were any substance to those QE reports. Sniffs of incompetence or at least a lack of focus and sloppiness,
From memory the issue with QE was vibration of the propeller caused by debris probably picked up on exit from Rosyth docks which knocked the blades out of alignment,can’t remember any issues with shaft alignment in that case.
Blast probably Russian undersea special ops team
This smacks of pore assembly of components by pore workman. Why wasn’t this misalignment spotted by those that layed the keel?
There are other limitations such as shaft bearing temperature and hydrostatic impact in way of the shaft and it’s bearing which often have not manifested themselves until the vessel has been in service for a short period. In these cases it occurred to VLCC’s but my intention is that there can be other factors.
Whoever (i) set the limits and/or (ii) designed a clearly ineffective vibration detection system should be firmly established & should be prosecuted through the courts for negligence. They had a ‘minimum’ legal duty of care & failed in that duty.
Well, you can, but it’ll be putting strain on it all the time, so it’s just a matter of how long it takes before something gives.
Absolutely right,or else check bearing temperatures constantly.Flexible coupling of which type???Vulkan coupling or what type of coupling being used???But coupling will be checked at ideal rpm in docktrails at harbour.??Then what could have been gone wrong..??Something fishy I believe???
Good the problem has been identified & is being fixed. Improper installation looks like the builders responsability, financially. Odd it took so long to manifest itself though. If you value freedom, democracy & the rule of law; with major players becoming more aggresive, the sooner we get two operational carriers(& more escorts-we’ll soon be down to 16 by the years end!) the better & safer we’ll be.
Not convinced. We’ll only have enough aircraft eventually for one carrier (if that) and I suspect it’ll be too important to lose. I reckon it’ll be kept out of harm’s way should it come to hostilities.
The carriers were built by a consortium – multinational. Arguing over which company was responsible. Very weak UK Project managers, which are guided individuals in the Cabinet Office. People like Michael Keegan (Fujitsu’s Front Guy during the Horizon project for the Post Office – which failed spectacularly and resulted in many Sub Post Masters being ruined, jailed or taking suicide as a way out) Old boy’s network. From my project managers background, you have to stay focused and ask the right, searching questions. There must be individual logs and checklists for the prop shafts. The design engineers working on vibration measurements must use this as learning point. Condition Monitoring of the whole assembly (produces a unique, ecg like, signature, under differing conditions) throughout service of various components.
Let’s get them into service!
Shaft coupling work is a nighmare . If the coupling is installed incorrectly you wont know until it lets go which appears to have been the case here. Bad Vibro readings probably wont show up because until it does let go (probably through metal fatigue) it will continue to do its job.
I have renewed sheared off couplings on USN ships, which where down to metal fatigue. A contributing factor was the instalation which wasnt 100% accurate. The couplings I have worked on where hydraulic shrink to fit. You had to get the shaft insertion accurate to within 1mm at each end and the expansion and contraction hydraulic pressure system needs to operate at specific pressures up in the 50 K PSI range to shrink it on. Get any of it wrong and its likely that the coupling will fail ahead of its service life.
I made the motor ends of those shafts including what I would loosely describe as the armature…..an absolute pain in the ass for my guys to machine and assemble!
So reporting hissy fits not withstanding, don’t think this would get into top 50 for the Ford in terms of cost or importance!
Well the Ford is at sea as we speak with a full battle group and a air group that can basically take on anyone on the planet. Yeah it’s been a long road. Transformational things are. Getting your propeller to spin is not one of those
These things happen, one good thing is it happened when the other carrier was available and the problem is known and being fixed. Glad we have people like yourself to sort these problems.
Have you heard anything about the petrel ship in leith that fell over?
I was reading comments on YouTube and someone who said she has been righted a day or 2 ago. Couldn’t find anything else about it being moved.
Then someone else said she may have fell over due to needing higher than usual custom made blocks due to the APU sticking out the bottom. Blocks 2.5m high at least. Normal ones aren’t that high? These folks could just be talking utter trash as it is YouTube comments😂
Bilge and keel blocks are usually less than 2metres high. Side shores have mostly been dispensed with but that can depend
on the Hull form of the ship being drydocked.
Petrel now floating upright.
I
I work in the warm and sunny middle east so cold and wet Scotland isn’t that high on my radar!.
That said, we Dock ships here using keel blocks that are well over 2m high… Some are over 5m in height to allow for the prop sweep below the hull. It’s down to the docking plan you use. In the case of the Leith incident it looks like the breast shores failed during high winds with the ships side acting as a large sail area. You can add side/wing blocks next to keel blocks that help with stability as well as the Breast shores. That’s the method we use to move ship sin and out of the water using our railway slipway. We can move ships up to 5k tonnes on it and we have 2 lanes. We have had some big ships, civilian and military on it without issue and no breast shores required
Lucky you GB, the Brecon had too be put on blocks in Dubai in 91 due too shaft wobble we thought great we’d be put up in a 5 star hotel ended up on one of the roundtable RFAs
Done Hunts and Sandowns on the slipway as well as USN, USNS, BDF ships. Still to do a big RN ship in the drydock… Nearly managed it a few years ago but a UK Minister bottled the risk assessment and wouldn’t sign it off so it was an alongside maint period.
Alongside I have done done T23, T45, Bay, USN AB, Tico, USNS from tugs up to Supply ships, RAN Anzacs…. All good fun
Thanks for the info. I never take what some people say on the internet to be true. Come ask the experts here. I’m only 10 miles from the ship but still haven’t found the time to go for a look.
With working where you are do you get air con in the docked ships? Be a hot box sitting in that sun without.
It’s a balmy 32 degs now. Yep we have AC internally and fans for the engine rooms. The fun part is doing tanks. No AC, blown outside air. Tank washing, blasting and painting is a god awful job when it’s hot and humid.
eSysman SuperYachts has done a couple of reports and videos about the Petrel on Utube
You won’t know, but it’d be difficult for the person who fitted it in the first place not to notice…
There is an old RN joke about tiffies working to the nearest “thou” of an ich; Electricians to the nearest switchboard and shipwrights to the nearest. Ship. Precision engineering is not for the faint hearted.
I’m a retired mechanical engineering fitter and I’ve seen couplings and shafts give way if slightly out of line either vertical or horizontal.
What you’ll find is some engineers will pull the shaft straight against the bearings using a tirfor get the bolts in tighten them up to spec and bit more. This will cause a vibration and a wearing of the bearings especially if the’re white metal
How the he’ll did the POW passed OST prior too the Navy signing for her, surely Officer of the Watch maneuvers would have shown the defect then ?
I *suspect* it ran like this.
During builder trials all the experts were onboard with the extra sensors etc.
The high speed runs were done – nothing was picked up so the sensors and alerts systems were calibrated around the vibrations picked up.
It could be as simple as a decimal point off in the monitoring software?
Or it may be the trials were not done competently?
Maybe a mixture of both?
Maybe the axis of the vibration sensors was crossed over in wiring?
Most of these things are not singular errors but a chain of medium sized errors which causes a catastrophic failure.
Cheers SB , I doubt if 30% of port or strbd wheel will be the Norm for OOW maneuvers when POW sets out for sea trials just in case fingerscrossed so too speak just Kidding
The trials will stretch her to her limits to make sure she doesn’t fail in a mission critical situation?
UK shoul better buy american CVN.
So what parameters will be used during sea trials to prove that the realignments are what they should be and that we don’t get another coupling failure . I’m sure the trials will be better monitored by people who know what they are doing and that the test equipment is better than the last time. Another failure would be the last nail in the coffin for the carrier strike group .
TBH talking to a USN friend the QEC program us viewed as an impressive success over there.
There is a genuine school of thought that some QEC type carriers are needed along with the Fords / Nimitz / Gators as the availability and costs of the Nimitz / Ford is eye watering. Sure they are the best of the best but in so many situations they are not needed and the issue comes back to Can’t Be Everywhere.
Whereas some QEC numbers give USMC F35B valuable alternative roles as they are an airforce in themselves.
Sure there is masses of pork barrel politics over Ford build and Nimitz sustainment programs as well as USN elements being nuclear carrier focussed.
China is a threat: how do you upscale rapidly.
What nails have been hammered into the coffin already for you to say it would be the final one?
Considering Prince of Wales has spent most of its life getting repaired for various documented issues , and if they don’t fix the current propulsion issues correctly and it fails again then it deserves to be mothballed .Could be a £3 billion white elephant .
Depends on how far the cat is that’s being buried… Already been a good few nails how many more would you like… QEC’s and T45’s really have been a huge waste of money. 30 to 50 year life span? Yup even if half there life’s spent in dock and only with a skeleton crew
It was damaged by the Russians the cat and mouse games which involved the Nord2 pipeline. All these investigations are a cover up. There is no way the UK can fail to design a ship with all the knowledge and experience.
Just get it fixed ASAP we will need it if things don’t improve soon
Seems a cheap fix on the scale of what the ship cost, dry Dock fee’s, insurance etc. 🤔
Dr Barry William Maiden Phd eng Bsc eng Ch.eng FIMARE it’s simple the ship builders are responsible for all repairs due to the warranty given by the makers
Even after agreed sea trials as this is not due to normal wear and tear
We all new these two vessels were a disaster waiting to happen as they were built by yards who had lost two generations of shipbuilders xxx
Pay peanuts and you get monkeys. UK has lost its deep technical expertise. Leadership is thin. Burdensome bureaucracy. Institutional degredation.
In engineering we call this…”it wisnea me” what happened to Scotty shouting she canea take much more of this captain. Sounds to me another MOD cover up… £3.2 billion cover up. I think it’s best if PWAC goes to the western isles we’re a couple of ferry’s down the noo.
After years of shaft alignment using RDI, Rim & Face, and latterly Pruftechnik Rotalign (Laser) there is no excuse when using ‘Rotalign’ in not achieving the desired alignment. Pruftechnik also have live alignment monitoring available the alignment being monitored in real time and under load. Questions which spring to mind (from Supertanker shaft alignment experiences) are there external influences being transmitted, have the correct mechanical and thermal offsets at the couplings been calculated, is the ship hogging or bending influencing coaxial alignment. Anyone who has aligned shafts using Dial Indicators either by RDI (two Dial Indicators) Rim and face (trig) will know the challenges but these days with laser alignment there is no excuse for error however shaft alignment is complicated and aligning ship prop shafts is far more challenging than aligning machines on land.
Tolerance at the coupling rim would be around +/-0.005″ TIR 0.127mm