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?

UK CAA say no to This type carrying out AOC work over hostile environment TFN
 

HC....tell us again how the EC products are so vastly superior to the 92.

Interesting! I guess this doesn't apply to the Mk1. Mind you I don't know how many Mk1's there are still around

As I am no longer flying, I don't have a technical opinion on either type, but hasn't the S92 had its fair share of MGB problems too?

And before I get blitzed I was a high time pilot on both Sikorsky and As332L's :ok:

SAS
 

I think the nation that gave us solid rocket boosters that go 'pop' should at least avoid sticking their necks out quite so far.

You know the old saying, what goes around comes around. Crow now if you want but beware of having to eat crow pie sometime later.

G. :}

FYI, AS332L, L1 & L2 are all included if "equipped with Main Gear Box (MGB) bevel gear vertical shaft Part Number (P/N) 332A32.5101.00, P/N 332A32.5101.05, P/N 332A32.5101.10 or P/N 332A32.5101.15, all Serial Number (S/N".

Sorry, I've not understood properly so clarification would be appreciated but - did I read in the previous pages that Eurocopter are now saying that with regard to the 225 vibration (HUMS or whatever it is called these days) analysis must be conducted after every flight as Bristow (apparently) already do?

Isn't every 25 hours? I think I saw that at the other thread (G-REDW)

Aircraft with the affected Drive Shafts, which include 225, and some L2's and even 332's are subject to varying levels of scrutiny.

332's can fly for 6 hours between HUMS checks
L2's 4.5Hours
225's Just 3 hours between checks

So effectively after every flight. But even if allowed 6 hours flying, why wouldn't you do it after every flight???


In addition, the CAA have just effectively banned flights on these aircraft types (fitted with the suspect part) from flying over a Hostile Environment.

Lets hope for the benefit of the whole North Sea industry that we sort this issue out quickly, safely and permanently

Geoffers....twas not I crowing about the 225 back when Brother Lappos and HC were arguing the various merits of the two aircraft.

As you rightly say....what goes around....comes around.

I anticipate the same folks that were so critical of the 92...rightly so in a lot of regards....should also rightly hold EC and the 225 to the EXACT same standards they did of the 92.

The key difference between the two situations is the 92 was a new design and being fielded without a long history of good service to allow for generating a historical data base for comparison purposes, encountered some very unforeseen problems, and seems now to have overcome its initial problems.

The 225 on the other hand....did just the opposite....used legacy engineering based upon a well proven design and just recently has encountered some very severe problems that are the result of tinkering with a basically sound design (in most regards) despite having some adverse design issues.

I just like to see some fair play when it comes to discussing the relative merits of two very different designs....each has its strong points and each has its not so strong points.

If they had not altered the main gearbox shaft on the Super Puma none of this would have happened.

Well SAS, for a start how many have been killed in S92 vs 225? Anyway, a heli is only as safe as its weakest part, for 92 it was the gbx oil system (filter) and for 225 it seems currently to be this shaft. S92 had a head start on catastrophe, now it is 225's turn to catch up a bit, but now that the fleet has effectively been grounded this problem will be fixed and without loss of life. Apart from these weak points in each fleet, the 225 remains by far the best from the HMI point of view but since you have flown neither, you wouldn't know.

Everyone else - SAS loves to throw bait at me and if I didn't bite on it, I would be depriving the old chap of his only pleasure in life, so I just have to do it because I am such a nice chap and hate to see a grown man sobbing...

Realistically, what replacements are there for the EC225?

I disagree. Although no-one wants to end up in the drink, chances are that in a controlled ditching, everyone will be OK even if the weather is not as good as it was for these events. IIRC no-one has ever died from a controlled ditching in N Sea in its entire history, and that is an important concept for everyone, especially our passengers, to bear in mind.

Its called "needing a wash" got one in the end!!

On Point
 

That you are, P3.

Especially so if, with rough seas, the pilots chose to ignore the published procedures.

With regard to the frequency of HUMS downloads...EC allow up to 25 hours without data. I presume this will now be reduced to, as mentioned before, somewhere in the region of 3/4 hours/between flights

Where are EASA and the DGAC?
 

So the UK CAA have unilaterally grounded NS Puma's. Shouldn't this action have come from Cologne, EASA HQ?

Are EASA scared of upsetting Eurocopter or possibly the French DGAC? So prevaricate and choose to do nothing more than rehash an old AD!

At times like these you want strong leadership from the authorites and congratulations to the UK CAA for taking the lead. :ok:

HC, this is true but one of our 332 family accidents was fatal. It wasn't just the passengers that were killed, some were our colleagues. There still isn't a positive conclusion from this accident that was MGB related. Just because it didn't happen at Bristow doesn't mean that it isn't very much still in our minds, particularly in the light of recent events. At the time, EC were very keen to lay as much blame as possible with the operator to protect their reputation - ironic doesn't even get close.

I think that if you do a little digging you will find a close connection with EC at EASA. Well done to the CAA for taking this decision, it renews your faith.