Concentric,

Further to my previous about the different oils - when using "mineral" oils the service period of flight hours and calendar period is much shorter.

That could easily contribute to a large proportion of the better result.

WRT your comments about "silica" - could it be something as simple as a poor vent on the gearbox allowing it to enter from just airborne debris? Dumber things have happened, wood for trees etc.

I did point out and demonstrate to a certain associated manufacturer how water was getting in to their gearbox which resulted in numerous changes to the venting and fixed the issue.

The unusual thing was that if you had any experience with older aircraft and different manufacturers the fix was obvious! No need to re-invent the wheel!

There is also at least one larger influential operator actively working with Airbus to bring the 225 back to commercial service.

Can you imagine the consequences of another one shedding the rotor system?
1 is bad luck, 2 is negligence, 3 would be a lawyers wet dream.

I could see them being used in the utility world for fire work where paying public aren't sitting in the back, with no one else wanting the airframes acquisition should be a fraction of their original value.

Operators can only bring them back if they have customers.
I really can't see any significant N/S oilco dare to specify the 225.
That shot of the rotorless Bergen a/c haunts the industry like the shots of Piper Alpha.
Oil Cos like to think of themselves as Gung Ho cost cutting warriors. The reality is that when it comes to HSE they are a flock of corporate sheep. It's dead Jim!

Why do people think the 225 only operates in the North Sea?

Before the grounding, what percentage of the worldwide fleet, including the military machines, were actually operating there?

We don't think that, what we know is that the main 2 countries that operated them in the north Sea, grounded them, the rest of the world carried on as normal (after a short while) rightly or wrongly.

Of course they will try. They are tied into multi million pound leases/purchases and can't afford to abandon these aircraft.
What they obviously don't realise is the strength of feeling against flying in them again.
After the first incident I was one of quite a large number that refused to fly in them. For this we were treated to a day at Bristows being shown how good they were and the extensive checks and maintenance that would prevent it happening again. What are they going to do with us now?

There is no commercial imperative to bring the 225 back into service, North Sea or internationally. There is no shortage of S-92 capacity to fill the heavy requirement and Super Mediums are increasingly filling intermediate requirements.

Bringing a 225 on contract would probably displace a 92 or 189 /139 which are all cheaper to operate anyway. The 225 has always been more $ hourly than the 92 and with changing MGBs every 1000 hours will only be more expensive again. So, as an operator, one would really have to want to rather than need to bring it back.

We have all been told that this is the most scrutinised MGB ever, 3 or 4 times now. This time I don't believe it and I won't be putting any passengers in it.

In the US, most newer rotorcraft gearboxes use a dedicated transmission oil like DOD-PRF-85734 or a commercial equivalent, rather than turbine engine oils like MIL-PRF-7808. DOD-PRF-85734 transmission oil is a synthetic base lubricant that is hard on some materials and finishes. So one consider with using this oil is ensuring all elastomer seals and coatings are chemically compatible.

Would that include the Sikorsky S-92A tailrotor drive I wonder?

What became of the AS332L/L1 fleet? These helicopters dominated the marketplace and then just seem to have vanished completely. Between the L/L1/L2 and 225 all disappearing, this must have a major impact on Airbus revenues?

New 225 bookings for the North Sea sector started to dry up a couple of years ago, well before the grounding. Airbus forecasts for the 225 predicted the majority of business would come from the military, and so it was proven. The grounding in some sectors, has had a slight impact on revenue.

The 225 effectively replaced the L / L1 and even L2 in some areas. Faster, smoother, better payload and with new avionic technology, it made the L Series commercially obsolete. Many Ls ended up in the secondary market like the German Border Guard. Vector bought some I think. Some were canniblised for spares as support was becoming expensive and difficult. Some even went to the scrapyard. There was a brief resurrection when the 225 was grounded first time.

A few of the old buses are back flying contracts in Australia (and East Timor), since the demise of the 225

As I have said many times before here I think the North Sea market is pretty much over for the 225, and not just because of the accident. The O&G market has been down longer than before and other than in the US is not showing much of an uptick.

The 225 (or rather its military versions) can certainly be re-engineered to have a bright military future and there are areas of the world where it can continue commercially.

The elephant in the room which is just not going away is doubt over the safety of the MGB. Nothing that has been said yet, is going to change that. However, there is nothing to stop AH setting out a radical re-engineering plan or, if/when it really knows, to explain exactly why this happened and a clear indication that that has been fully fixed.

Apart from the X6 project....

that is still someway off but yes I agree they could just slow burn until then

As I said, picking what you wish to hear does not change the fact. Report is coming soon and the conclusion is quite interesting.

I suppose they could make the top bearing housing and support lugs out of stainless steel with steel support tubes down the roof. At least the rotor should stay on should the upper planetary disassemble itself.

Whether you can control it is another matter.