Read it for yourself - Statoil Report

Interesting if you "read between the lines" of some of the inferences.

Particularly the sections on contracts and performance and why they have been brought to light.

You want to dramatise it by saying "main shaft failure" but I would call it "oil pump drive failure" which is what it actually was. But I appreciate that sounds far less theatrical and thus doesn't suit your agenda. I seem to recall the precious S92 had its share of oil pump drive and design failures but you've conveniently forgotten to mention them.

And is a controlled landing on the water an "accident"? I guess it depends on your jurisdiction.

Under ICAO they would both be classified as accidents as bot aircraft were damaged beyond economical repair, or written off in old language.

Twist and Shout emphasises my original point, the oil and gas industry no longer trusts AH. As has been said before, the market has re balanced. There is even a surplus of S-92s now.

HC,

From an engineering perspective it ought to be appreciated that the main shaft in the 225 gearbox is multi-functional. It is supported in 3 bearings, 2 near the top very close together (possibly even contacting) and one near the bottom but above the oil pump drive. That bottom (radial) bearing appears much bigger than needed to react oil pump loads only. It locates the main shaft radially and reacts a moment due to the eccentric contact between the input drive and the axis of the main shaft. Indeed the proof of that lies in the cyclic bending stress that propagated the fatigue cracks, severing the shaft above the lower bearing. If the fatigue loading had come from the oil pump drives the shaft failure would be expected below the bearing.

With the shaft broken not only is drive lost to the oil pumps but the 2 upper bearings and their supports are subjected to loads which I very much doubt they would have been designed for. Evidently, and fortuitously, they survived long enough for the ‘precautionary’ landings on water but can anyone say how long they would have lasted without lubrication and cooled only with a 30 minute spray of glycol?

Wow. You really have been endoctrinated and blinded by the Eurocopter lies. The main shaft in the main gearbox sheared in two. How is this trying to dramatise things? Arguably (and highly fortuitously), the occupants were saved due to the erroneous indication that the EMLUB system had failed.

And I think you've got me pegged with the wrong 'agenda'. I know full well that the S92 has got it share of issues (and I'm personally very glad that I don't have to fly it). However, I was responding to your post that seemed to imply that the EC225 has only been involved in one serious accident.

And, yes, regardless of a particular jurisdiction's definition, when an aircraft has to ditch in the sea due to a broken gearbox, it is definitely an accident.

Yes I know all that, but the fact remains that the sheared shaft only caused loss of oil pump drive and the remaining bearing showed no signs of distress. My point is that you could present this in one of two ways, either as a loss of oil pump drive which, with functioning emlube, allows 30 mins at Vy (which of course probably doesn't get you very far, 40nm still air minus the time taken to land). Or you could present it as "main shaft sheared, rotors nearly fell off shock horror" except of course that the rotors didn't nearly fall off.

It's all down to how emotive you want to be.

2 of my 3 all-time favourite helicopters are French, but no matter how many times they change the name, Sud Aviation/Aérospatiale/Eurocopter/AH have always had an arrogant 'we know better than you' attitude and the most appalling so-called customer service and dreadful spares support.
As far as the 225 goes, I'm with SAS, NEO et al

Statoil will not use type of helicopter involved in crash again - BBC News

Statoil will not use type of helicopter involved in crash again

An oil firm has said it has no plans to ever again use the make of helicopter involved in a crash which left 13 people - including an Aberdeenshire man - dead.
Iain Stuart, 41, from Laurencekirk, was among those killed in the crash off Norway in April.

The Airbus Super Puma H225 was flying to Bergen from the Statoil-operated Gullfaks field.

Statoil said it would not use the helicopter again.

The model in question has been grounded in the UK and Norway, but Statoil said it would not change its position when the suspension was lifted.
Air accident investigators found a fatigue crack was the "most likely" cause of gearbox failure.

I think that was covered in Posts 2 and 6....

I guess we won't be hearing offshore workers being told to pull on their big boy pants any time soon?

Never took mine off.

Correct me if I am wrong.....the Main MGB Shaft failed......right?

What was designed to be a single item became "two"....where I come from that is called a MGB Shaft failure!

No matter who designed it or what part number is on it.

Yes, I expected you would...But what shocked me was the AAIB report into REDW and CHCN revealing that the manufacturer’s designers apparently did not seem to know it at the time of certification (Ref. AAIB 2/2014, 2.6.4).

Between main shaft design and planet gear/bearing design, the manufacturer does not seem to have had a very good grasp of FEM.

Sasless being sasless. You are taking it too serious.

The old AS 330 had the transmission oil pump on the LH accessory drive on the rear of the gearbox although the pickup was still at the bottom. Civilian use required a back up system on the 332 so they designed this Heath Robinson system placing both oil pumps dependent on one drive at the bottom of the gearbox.

In retrospect it would have been far better to have put the secondary oil pump on the RH accessory drive together with No 2 Alternator and No2 Hydraulic pump.

Doesn't help when you reduce the planet gears from five to four.

Mee3......putting Lipstick on a Pig doesn't change anything as it is still a Pig.

There are certain mechanical failures that must be seen exactly for what they are.

There have been plenty of explanations why a failed Main Shaft in the Main Gear Box is a far more complex and dangerous issue than merely losing drive to the Oil Pumps.

As we have learned from the loss of Rotor Systems because of such failures should make that abundantly clear even to the most obtuse amongst us.

This is not another argument about the various merits of the 92 compared to the 225 as a few wish to make it.....this is all about a failed design of exactly one kind of MGB that kills people.

I suppose there are some that attend here that think by clicking some Slipper Heels together and making a wish that all will be well.....but that is not reality.

The reality is the 225 is DOA....dead on arrival in the Oil and Gas Industry.

You can make like a River Dance on Steroids but all the Heel Clicking in the World is not going to change that.

I do not think that "a failed design of exactly one kind of MGB that kills people" is supported by the numbers.

It would be lovely to live in an alternative universe where the perfect safe helicopter was possible but we don't. We edge safety to ever-greater levels as the technology allows. The current generation of rotorcraft in this weight class have done this quite successfully. That success continues.

Damning the 225 in the current circumstances creates a very real risk of replacing it with something worse.

The discussion starts t head in the inevitable Pprune direction...

I am self loading freight in these machines and so have some interest in them holding together.

Normally it would be considered very surprising for a manufacturer to state that their product was perfectly safe to fly - before the latest investigation report is delivered.
For a certification agency to support those statements and strongly suggest the aircraft is safe without modification or the report published is again very unusual - until you realise the national and commercial aspects of this case.

The vulnerability of the main shaft to failure started the concerns. Whilst virtually all the attention was there, the planet gears were apparently spalling and AH's understanding of the gearbox behaviour considerably lagged operational experience.

As to the comment that the replacement could or would be worst? Pretty unlikely you would have to step back to 1960s designs to see this level of componentry failure - which is not impossible but would mean any manufacturer would be toast - which may be where AH ends up.

The real disappointment is the certification system. Both the 225 and 92 have a significant level of 'grandfathering' in their approvals - with more of that happening in the 225's case. It has significantly undermined confidence in the certification process - the first 92 failures occurred at shockingly low fleet hours. Whilst the filter issues are now supposedly sorted I've not heard a fix to the gearbox foot cracking - is it all resolved now?

Pushing up power and weight and making incremental changes to compensate is the classic method to create engineering failures. The best example probably being bridges - where every concept has be enlarged and enlarged until the point at which it failed.

But back to the plot, I wish the best of luck to any management team trying to persuade their offshore teams that rotors flying off the machine is sorted - without a shiny new and much better gearbox.

gasax - Suggest you have a close look at the TCDS for the S92. Not sure I can agree with "significant level", not even close!

Gasax - the gearbox foot cracking was fixed years ago, the new feet are about three times the size of the old ones.