I don't think that you understand the significance of the failure in both this accident and G-REDW. The main shaft in the gearbox has effectively sheared in two, due to the weld failing.

The emlub system is not designed to deal with a failure of this type, regardless of whether or not it gives an erroneous failure indication. The emlub is designed to work if there is a total loss of the gearbox oil (due to, say, the MGB case cracking). This is not what has happened to G-CHCN and G-REDW.

@Bravo - exactly.

What is of concern is that why any conclusion is taking time. This stuff will be easy to track to back through the engineering process and one hopes in the fullness of time that its not commerical pressure coming into play.

The whole of the NS is at a virtual standstill save for a few flights. The last time we had this, EC issued the 3hr HUMS inspection routine. The companies then realised that you can't do much with a 225 in 3hrs especially if you have rigs in the ESB served from Aberdeen. It was then extended to 4hrs. Technicalities aside, what do you think the customers are thinking? They want to get on with their business but have a workforce, quite rightly, who may not be convinced. We also have a workforce of pilots who, in some cases, have seen three MGB failures in 3 years. It will be extremely interesting to see how this pans out and will give a true reflection on the real ethos of the industry.

Once the bears stop boarding there is nothing the oil companies nor operators can do.

As a pilot I would be very reluctant to go out and operate a machine with a proven deficiency as long as there are no clear and decisive steps taken to mitigate the risk. I would want proof that my MGB is not about to thrash itself to bits, not just a general assurance that with a bit more monitoring it will be ok. That did not work last time either.

And I speak from personal experience of my type being grounded after a fatal accident caused by technical failure. The first few flights after we were cleared to operate again where still quite scary and all of us were extremely vigilant.

Was there any history of gearbox problems on Super Pumas / 225's prior to the 85N tragedy ?

Would seem odd that it has just become prevelant in last three years or am I being a bit oversimplistic ?

My personal opinion is that if you guys are happy to fly the aircraft every day then I think my hour and a half each way every month is no big deal, unfortnately a fair few of the punters offshore don't think the same so may have to find a new line of work .

http://http://www.aaib.gov.uk/public...ma__g_redw.cfm

Page 6 onwards....

and perhaps when they say this in July you'd think you would have an answer by now:-

The investigation will continue to review the results from the fatigue tests, with other data and evidence, to establish the mechanism that caused the initiation and propagation of the fatigue cracks in the bevel gear vertical shaft. It will also review the manufacturing process, dimensional inspections and quality system.

Offshorebear
There was no problem before the last few years. The reason is that previously the gearbox shaft was different; the part No was 331 something as opposed to 332 something. Super Puma 332Ls were fitted with the old shaft and those that still have them are not affected. Those that were replaced with the new shaft and all 332L2s and 225s that are fitted with the new shaft are under investigation.

Fareastdriver, that's true but it is strange that we have been operating EC225s for the past 7 years, with over 70,000 fleet hours and never had a problem. This spate (well pair) of problems with the vertical shaft does suggest something has changed since the introduction of the 225, I am just not sure what it is.

Well in the AAIB report it suggests that a process changed in 2009...

Without trying to be smug but this isn't complex. The process involved will be well documented at all levels, and Eurocopter has annual revenues of around €5 billion.

How hard can it be?

S76Heavy, you say "... The first few flights after we were cleared to operate again where still quite scary and all of us were extremely vigilant."

As a regular passenger on 225s, I would like to think the flight crew are always EXTREMELY VIGILANT :\

AND another thing - further to the discussion on frequency of data analysis, I don't understand why the bevel gear and oil pump gear mesh frequency detectors aren't clagged up to orange and red lights on the dashboard not to mention remotely monitored.

Oil platforms do continuous vibration monitoring on safety and business critical kit - if a compressor or turbine throws a wobbly, it is displayed real-time on a computer screen on-shore.

How come the aviation industry is so negligently lax in this respect?

If a new or changed material is the cause of this, the question should be why was the change made. Being cynical I have to say cost.

I owned a Citroen car (the ones with hydraulic suspension). After 6 weeks from new the High pressure pump failed. Reason? They had changed the type of bushes to cut costs. They eventually reverted to the old type bush, but the whole episode must have cost more than using the 'cheaper/inferior' bush in the first place.

"I have the EC ASB now giving 3 hours between downloads for the EC225."

Whether it is 3, 4 or 5 hours between HUMS downloads, I believe that the specified maximum period will have to include all rotors running time on the ground and helidecks. To the best of my knowledge and belief, the lubrication pumps and the bevel gear on the shaft are incurring the same or similar wear and tear, airborne or not.

This will impose a serious limitation on the radius of action, because non-airborne time accounts for something like 15% to 25% of total running time. Senior Management is aware of this.

There's an old saying; 'If it ain't broke don't fix it.'

This gearbox design has been going since 1966 and over the years, 1971 to 2008 in my case, and it has performed flawlessly. It wsn't until it entered civil service in the mid seventies that a gearbox oil pressure guage was even fitted; before that it was just an MgpP warning. The obvious structural difference between the two is that on the old ones the pump was mounted on the back with the alternators and hydraulics as the shaft had to be kept hollow for gunsights etc. I can understand using the shaft as an alternative drive for a standby system but why the main one as well? and if it did work why change the material.

Another example of this saying was with the BV 234 Chinook. They had millions of hours being beaten to death in Viet Nam without any trouble; the North Sea was going to be a walk in the park. For some reason they decided to make the front gearbox bevel gear in two pieces; possibly so that only the wearing surface needed to be replaced at the TBO. What they did not expect was corrosion to fracture the coupling between them and cause the gear to fail and cause the disaster at Sumburgh.

One must wonder how many problems are caused by nothing more than change for the sake of change.

Who's going to accept something like : "trust me, I made calculations, should be ok if you don't use it too long" ?... :rolleyes:

Or you answer : "come on board to tell us when it's time to go back" :bored:
.

You already do

Yes. Design Verification.

To use something that had several severe technical problems (that can kill me and people I'm responsible for) with no other corective action than "don't use it too long" : I can be wrong but I don't think so.
.

Are L2/225s grounded worldwide?