North Sea heli ditching: Oct 2012

[Pittsextra]

Yes I understand the stable state logic and I guess they have increased the priority for data collection for the relevant components. Although given the sweep of data collection takes around 30 minutes and the helicopter to be in a normal flight regime some condition indicators might not log very much data. In fact it would be interesting to see a data table for what is actually logged.

The time critical nature of indentifying a faliure and the effective lack of reliable data within timescales that correlate with the short time available to indentify any failure mean that with the current system its very hit and miss.

Especially given the need to indentify a significant up trend... So what is that absolutely??

As for flying on for 30 mins well forget that, it is the single most stupid piece of advice anyone could give.

Edited to add :- if you can tell from the download time at what point in the flight the acquisition was made why does the 3 hour flight time not start from that point??

Also I understood that if no data acquisitions had been made for 10 hours flight time it would flag?

[Pittsextra]

Also:-

Previous to yesterday the requirement was to check the download at the end of the flight and if the MOD45 acquisition was below the limits and no significant upward trend was noted the aircraft could go for another 3 hrs. This was reasonably fine for people who do a lot of straight and level with lots of acquisitions. However it didn’t cater for the people with a low number of acquisitions, the change is to tighten up on the foreseeable possibilities of operation.

So its taken a month to figure this out? EC on the ball.

[Pablo332]

if you can tell from the download time at what point in the flight the acquisition was made why does the 3 hour flight time not start from that point??


It sort of does with effect from yesterday.

Edited to add

Also I understood that if no data acquisitions had been made for 10 hours flight time it would flag?

I may be wrong but I think you get a warning after 5hrs. At the moment if you don't get information for more than 3 hrs you have to NDT the shaft.

[Pittsextra]

Its a mess and effectively the thing is grounded because its got so confused to the point that no one really has a good hand on this.

But its pretty clear the issue is accepted so how and why now?

Of the EC225's you run what is the highest hours?

[Helinut]

I am not type-rated on these aircraft, but when I read the new EASA AD (released in the last 24 hrs) I got completely lost in the detail. Some of the detailed discussion was also less than reassuring, it seemed to me. The rationale still seems to rely on VM giving 100% reliable advanced warning, prior to failure.

Does anyone who thinks they understand where we are now want to give a summary in plain English?

[albatross]

Have any defective masts been detected prior to failure using the MARMS?
If so how many?

[Pittsextra]

Yes I'll have a go.

Much of the detail in the reason is sad and winding tale of how we got where we are now justifying the reasons and rational of prior AD's. Then we cut to the chase which is to try and keep these things in the air no matter what. (at some point the cockpit is going to be so littered with notices that forward viz might be an issue! - thankfully the CAA are not playing this silly game).

So the lastest one basically says with reduced torque that helps, that you can perform a check on the vertical shaft in situ that if you have M'ARMS check it and check it again and that there is now issue with AS332's.

With respect its becoming a bigger joke with each release and it feels like nobody at EC has a grip on this because the level of checking and restriction on the type show that essentially the EC225 is still FUBAR and the investigation is on going.

Someone needs to explain risk / reward to Eurocopter and EASA because the reward for limping on in this way is blown away by the downside of having another accident.

[MoodyMan]

Does anyone who thinks they understand where we are now want to give a summary in plain English?

In summary don't get onboard an EC225 or AS332L2, I'll certainly be refusing to fly on one in the unlikely event either of these Super Puma variants appears on our helideck again!

[helicrazi]

But this only applies to the post mod shafts, none of which are flying in the north sea, so theres no reason to not get on an L2 Moody

[Pittsextra]

AS332 with the old type shafts are unaffected by this AD although this effectively brings EASA, in a gentle way, into line with CAA for EC225 as it is practically impossible to comply with it in North Sea operation given the flight hours before check, maintenance flight or inspection of the MGB.

[Pablo332]

Things appear to getting far to serious here.
Letts lighten the mood with a little survey of all the engineers that might be watching.
With regard to the Mlube system.
Did you find the N0 1 engine interface (A) bizarre no gasket and the clamp appears to have an imperial nut on it. Strange for a metric aircraft (B) apparently designed for the job.
P2.4 valve had any problems? (A) almost always leaks, to one degree or another(B) appears designed for the job.
P2.4 intercooler. (A) There is no A (B) designed for the job
Hose intercooler to P2,4 pressure sw manifold. (A) strange angle should have had a 45 degree angle on it.It always looks crushed(B) designed for the job.
Pipework from manifold to MGB. (A) how do you test that without removing the box? (B) designed for the job.
Glycol pump had any problems (A) not since I installed the replacement (B) designed for the job.
Maintenance panel had any problems? (A) it appears to dispense glycol into the MGB every time I put the battery on post maintenance, (B) appears designed for the job.
Pressure switches had any problems? (A) not to my knowledge apparently someone has quite recently. (B) Appears designed for the job.
Procedure in maintenance Manuel for testing M lube system (A) please don’t interrupt me I’m searching the hanger to coble something together. I’ve no chance of reproducing the Mk 1 regulator as I’m a new operator my makabel kit looks nothing like the picture trying to find something to fit the hose from the engine is doing my head in, how the hell do you get shop air to test it with at the required pressure without the P2.4 valve sounding like its about to mutate (B) designed for the job.

Edited to remove poor spelling.

[Colibri49]

Funny that you should mention "Manuel" when it seems like Basil Fawlty could have had a large part to play in this shambles.

[Pablo332]

My bad. apparently I dident remove enought bad speeling.

[DOUBLE BOGEY]

HELINUT & MOODYMAN - where we are now is clearly explained on the Eurocopter website.

EUROCOPTER are testing an EC225 in the air at the moment in an attempt to isolate the cause of the crack in the shaft. They will continue to test until they, DGAC, EASA, CAA and AAIB are satisfied that they have identified the root cause. When they have identified the root cause they will set about working out how to overcome the problem in consultation and agreement with DGAC, EASA, CAA and AAIB. This is science not speculation.

EUROCOPTER are benchtesting a complete EMLUB system in order to establish the root cause of the erronous EMLUB failure indication under the appropriate MGB operating conditions. They will follow the same procedure as for the MGB until rectification is achieved.

In the meantime EUROCOPTER have issued an ASB to establish some interim management protocols for other variants that may be affected pending identification of the root cause.

This is a complex problem and EUROCOPTER cannot move forward without the agreement of at least 4 independant authorities.

I would suggest that the kind of science currently being deployed in the EUROCOPTER facilities far exceeds the experience and understanding of majority of the postings on this thread (including mine).

MOODYMAN - PM me and we can talk further about your worries re the 225/L2

DB

[Pittsextra]

DB with respect your comments about the future do not stand the test of the recent past and even the current!

Currently even though EASA have moved closer to the CAA's treatment of the 225 they still do not hold a common view. The AAIB are just a reporting body and will be guided by the CAA/EASA. So qualify what this means:-

This is a complex problem and EUROCOPTER cannot move forward without the agreement of at least 4 independant authorities.

Currently this is very far from science. Given what has happened explain the latest EASA AD which is the what 4th or 5th ammendment and tell me where science plays any part?? Its a total embarresment.

The MOD45 data is so flakey that you might not even get reliable data for as many as 10 flight hours - so when you have a problem that might need attention within 3 flight hours you have a directive which just fudges things to work around.

Its not beyond people here because much of the solution is common sense and yet so far we have seen a total absense of common sense from EASA and Eurocopter.

Moodyman - until this has a proper analysis and remedy just stay away from the type. At the moment they assume the AS332 is ok on the old shaft and yet nobody can tell you why. Is it design or material for example.

[cyclic]

Is there any truth in the rumour (doing the rounds at ABZ) that one operator discovered a crack in a shaft when it was boroscoped post the ditching although there had been no indications on MARMS up to this point? If this I true then I think it puts a completely different slant on things. I find it hard to believe that an operator or EC would keep this quiet....

[DOUBLE BOGEY]

PITSEXTRA - seeing as you seem to have all the answers why bother griping. Just phone Eurocopter and tell them the solution.

Telling a PAX to stay away from a type is fine but make sure include ALL the other types that have actually caused a loss of life.

[Pittsextra]

DB - THe only answer I have is to stop guessing at the answer and for EC to be brave and stop the drip drip of info that leads to further restrictions and work load on the ground crew that is a road that leads to those guys being over loaded and finger trouble. You know it does.

You said before :-

EUROCOPTER are testing an EC225 in the air at the moment in an attempt to isolate the cause of the crack in the shaft.

Is the same testing to isolate the cause that led to a particular set of shafts, that then wasn't when the October accident happened??

Good job.

Yes of course there are other types that have gone down but you know its the process here that is incredible. I mean whilst we are talking AS332L2 you might recall the accident that claimed REDL in April 2009 still had EASA Emergency (emergency!) AD's in July 2012 (see 2012-0129-E).

And in that AD it says:-

"Since issuance of EASA AD 2009-0099-E, the UK Air Accident Investigation Board published the final accident report. On the basis of these investigation findings, it has been decided to standardize the intervals of the visual checks of all electrical and non-electrical chip detectors, and to require this check for all models of the Super-Puma helicopter family, in order to increase the likelihood of detecting any adhered particles. This action must be accomplished on all rotor drive system gear boxes, i.e. on the MGB, but also on the Intermediate Gear Box (IGB) and the Tail Gear Box (TGB)."

Well the AAIB report into this was November 2011 so it took 8 months for EASA to the react but then and you might ask why is it the AAIB/EASA leading the way here and not the OEM?

Frankly I think it calls into question the quality of people at EC.

DB given your attitude to safety on another thread, trying to be-little peoples concerns is a poor show. Tell me do you think this has been handled well or that EC has done the right thing??

[Bravo73]

I find it hard to believe that an operator or EC would keep this quiet....

Hmmm, let's ask HeliComparator...?

[Variable Load]

Tell me do you think this has been handled well or that EC has done the right thing??
I'm sure the fact that Eurocopter are probably paying his salary won't influence his answer at all :rolleyes:

[HeliComparator]

Bravo, dunno why you think I would know! I have not heard this rumour so if it is true, which I think is unlikely, said operator is almost certainly not BHL.

Don't forget that it is not just EC in the fray here, but AAIB, EASA and UK CAA. If you think they are all keeping this secret from you then I am afraid you are suffering from conspiracy-theory-itis!

VL - does CHC do CRM courses? Maybe they forgot to cover The Sniper - I'm OK, you're not OK. Ring any bells?

[212man]

The AAIB are just a reporting body and will be guided by the CAA/EASA.

You are clearly not that familiar with the AAIB!

[HeliComparator]

You are clearly not that familiar with the AAIB!


Seconded!

It's a pity this discussion is degenerating into ill-informed scaremongering.

Bottom line is that AAIB are in charge and they are the only body that controls the release of info relating to the accident. EASA, CAA and OEM are just resources to be used and (in the case of CAA) argued with.

[Pittsextra]

I don't want to knock the AAIB but if the AAIB are the lead why do we have different treatment of the EC225 by the CAA and EASA? Since EASA released their AD 2012-0250-E the CAA release their SD-2012/005. In essense the CAA one is much simpler as it just continues to say:-

A specified operator must not conduct a public transport flight or a commercial air transport operation over a hostile environment with any AS332 or EC225 helicopter to which EASA Emergency Airworthiness Directive 2012-0250-E dated 21 November 2012 applies

Its logical that if the AAIB were the lead that these would be consistant?

In the case of the AAIB's final report into REDL you will see Safety recommendation 2009-051 in it it says (talking about an inspection of components of the MGB).... This inspection is in addition to that specified in EASA E-AD 2009-0087-E (which is perhaps odd because by publication date that had been superseeded by 99-E) and should be made mandatory with immediate effect by an additional EASA E-AD.

Then around 8 months after the AAIB publication you get 0129E which I mentioned before.

So really the AAIB are the lead? Did it really take 8 months to develop a process that is effectively saying "look harder"? Or do you perhaps think EC get involved with EASA and some lobbying took place??

Its a question and would be interesting to have an intelligent conversation around the process because it is sure that the one currently does not have safety at its core.

Currently the process seems to be carry on as ususal and then as we find issues the type gets more restricted. One thing that seems to be getting lost is that the first issue was highlighted in May so to suggest in late November that EC are flight testing isn't amazing.

[HeliComparator]

Pitts, the AAIB are in charge with respect to release of information about the accident. EASA is in charge of continuing airworthiness. UK CAA has an airworthiness department but I think only has a role to play for UK products. CAA Flight Ops has a role to play in those aircraft used for commercial air transport. They have gone against EASA and CAA Airworthiness dept by banning pax transport over hostile surface.

But EC and EASA don't regard N Sea oil & gas as the be all and end all of aviation. They have to consider the full spectrum of EC225 operators, some of whom might be private owners, or commercial aircraft not used for public transport. Hence it gets a bit complicated.

Yes the AD and EASB have evolved, but that is normal in the industry, these things often evolve as time progresses and new information becomes available. Perhaps you are a pilot not routinely used to looking at lower profile SBs & ADs?

What I find frustrating is the absence of, or drip feed of, info about the investigation, but that is down to AAIB's reluctance to release any info of which they are not certain. There is a culture of secrecy at AAIB until the final report is published. We normally consider this to be a "good thing" but in this case, it seems counter-productive.

Let's try to stick to technical argument and leave the conspiracy theories and berating of the parties for the tabloid newspapers!

[Pittsextra]

HC - why does questioning things make it either scaremongering or a consipiracy theory?

the AAIB are in charge with respect to release of information about the accident. EASA is in charge of continuing airworthiness. UK CAA has an airworthiness department but I think only has a role to play for UK products.

Agree but my comments are around the outcomes. As you say EASA are in charge of continuing airworthiness.

CAA Flight Ops has a role to play in those aircraft used for commercial air transport. They have gone against EASA and CAA Airworthiness dept by banning pax transport over hostile surface.


Why is this? I'm not seeking or suggesting something sensational, I'm just asking the question. Why is it different and do we think this is a good thing?


Yes the AD and EASB have evolved, but that is normal in the industry, these things often evolve as time progresses and new information becomes available. Perhaps you are a pilot not routinely used to looking at lower profile SBs & ADs?

Or maybe these events have allowed a better view at the decision making processes. Something that you don't seem to be defending yet seem to be critical of me being critical of it.


What I find frustrating is the absence of, or drip feed of, info about the investigation, but that is down to AAIB's reluctance to release any info of which they are not certain.

Yes and so given the need for certainty (which I agree with) after the May accident and the focus on vertical shafts given AAIB are the lead what generated the flurry of AD's around certain part numbers? It wasn't off the back of anything from the AAIB as far as I can see.. What was the old poster? Don't assume.....check.

Edited to correct formatting

[cyclic]

Bravo, dunno why you think I would know! I have not heard this rumour so if it is true, which I think is unlikely, said operator is almost certainly not BHL.

This is a rumour forum. The rumour is quite well founded and I'm afraid to say HC, that it could very well involve a company that hasn't ditched a 225 but was the keenest to keep flying post the accident. Now, there maybe absolutely no truth in at all but it would be a strange comment to have been made by anyone without a trace of truth. I'm sorry if this offends you, but you are very quick to criticise the other operators when you feel like it. You aren't a moderator of all things North Sea and if there is any truth then it could have been a lucky save. However, I think that if there is any skulduggery going on then it should come out in the open as EC seem to be hanging their hat on early detection of a known problem using MARMS until the root problem is solved. If I was flying a 225 on reduced torque and increased monitoring, I think I would like to know. Luckily, our authority don't think this is a grand plan, perhaps they know something we don't...

[DOUBLE BOGEY]

PITTSEXTRA - It may help you to understand the flow of information thus - EC, CAA, and indeed CHC are all bound by confidentiality clauses and CANNOT release any information without the agreement of the AAIB. I beleive this is a requirement of UK Air legislation, as I found out to my detriment some months ago.

In the past I have been in agreement with your position, but only when a helicopter type has remained in operational service after a serious (fatal) incident. As I result of my previous mistakes I now know better that it is not conspiracy, it is not secrecy, it is the necessary process that needs to be followed.

"Variable Load" - Nice to hear from you again!!!

[Pittsextra]

DB thanks for the information although I still don't understand why the CAA and EASA have different outcomes for the same events if the AAIB are directing.

[bigglesbutler]

Pittsextra can I ask a question, are you a PPL(H) holder yet or just a PPL(A)?

Si

[Pittsextra]

Both... the point being?

[HeliComparator]

Pitts, EASA Airworthiness and CAA flight ops have different outcomes because they have different remits.

EASA are concerned with the fundamental airworthiness of aircraft. Airworthiness is the same regardless of the type of flying operation conducted. The same rules apply to private owners as to airlines. I don't think it is within EASA airworthiness' remit to for example ground an aircraft for commercial air transport but not for private flight.

CAA flight ops are all about use of the a/c for commercial air transport and they currently consider the risk of operating the 225 over hostile terrain with pax too great. But don't forget that the operators and our customers decided to stop 225 flights before CAA came out with their edict, so UK CAA is not the primary reason why we are not flying.

[HeliComparator]

cyclic, if you are hinting at Bristow, the rumour is false, and so is the rumour that we were keen to keep flying after the accident. Quite the opposite in fact. Criticising operators based on an AAIB report is one thing. Doing so based on rumour and speculation (especially when it is untrue!) seems less meritorious.

[Pittsextra]

Pitts, EASA Airworthiness and CAA flight ops have different outcomes because they have different remits.

EASA are concerned with the fundamental airworthiness of aircraft. Airworthiness is the same regardless of the type of flying operation conducted. The same rules apply to private owners as to airlines. I don't think it is within EASA airworthiness' remit to for example ground an aircraft for commercial air transport but not for private flight.

CAA flight ops are all about use of the a/c for commercial air transport and they currently consider the risk of operating the 225 over hostile terrain with pax too great.

Yes however the CAA is a national body so why leave it to individual members to do something different and then why would they move away from the decision of EASA?


But don't forget that the operators and our customers decided to stop 225 flights before CAA came out with their edict, so UK CAA is not the primary reason why we are not flying.

Which isn't a ringing endorsement for EC, EASA or indeed the CAA..

[HeliComparator]

Pitts I'm sorry I can't better help you understand how these things work, it looks like it will take someone cleverer than me to convince you.

[Pittsextra]

Hey no not at all, discussion is a good thing.

I just think it is pretty logical for there to be a common set of regulations around these things?

In this http://ad.easa.europa.eu/ad/2012-0250-E (http://ad.easa.europa.eu/ad/2012-0250-E)

You have:-

"For EC 225 helicopters equipped with a serviceable M’ARMS system, and

operated over areas where emergency landing to ground is not possible

within 10 minutes at Vy, after the effective date of this AD, accomplish the

following actions:"....

And in this http://www.caa.co.uk/application.aspx?catid=33&pagetype=65&appid=11&mode=detail&id=5304 (http://www.caa.co.uk/application.aspx?catid=33&pagetype=65&appid=11&mode=detail&id=5304)

you have:-

"A specified operator must not conduct a public transport flight or a commercial air transport operation over a hostile environment with any AS332 or EC225 helicopter to which EASA Emergency Airworthiness Directive 2012-0250-E dated 21 November 2012 applies. "

Totally get the fact that the North Sea isn't the be all and end all as far as EASA is concerned but then to be fair the CAA isn't just talking North Sea either..

Surely it would be better if all were aligned?

[cyclic]

Rumour quashed by HC. It's official as HC has said so. I think a job on the Leveson enquiry would be right up your street - in fact you haven't got anything else to do now anyway;)

[DOUBLE BOGEY]

PITTS - be careful with the way you hand out your admonishments!! My attitude to safety on the other thread you allude to is related directly to my willingness to comply with the rules and regulations.

I am not sure of your frame of reference, but in the highly regulated world of Offshore Operations and in this case, the NS, we seek to always be compliant as to do otherwise would cause us not to remain employed for very long!!! This is a really simple concept that I hope even you can understand.

Like I said on the other thread. The first step to safety is compliance with the rules and regulations applicable to you and your particular operation. Thinking you know better, or simply not knowing the rules is not an option.
If you ever get to hold a professional licence/pilot or engineer, and you earn your living from that licence, you will learn quickly that non-compliance is not an option if you want remain employed, or indeed out of prison!!!

The situation in this case is fluid and dynamic and will almost certainly change again, possible many times, before this crisis is over. Manufacturers and Operator's are keen to get the EC225 back flying, but only when all necessary measures have been taken to ensure the safety of our passengers.

To a degree we have to place our trust in the process, the people employed to manage the process and the overlying regulations that are there to help guide us all through it.

The resistance you are are encountering on this thread is a result of your lack of understanding of the EC225 and technological milestone it represents. For those us us lucky enough to fly it, we understand that the considerable safety improvements in the avionics, AFCS and warning systems have been developed with the same technical capability and ethos of the people who are working to fix the problem right now. We know they will hunt down the problem and fix it. But it will take time!!

DB

[bigglesbutler]

Pitts

I am not sure of your frame of reference, but in the highly regulated world of Offshore Operations and in this case, the NS, we seek to always be compliant as to do otherwise would cause us not to remain employed for very long!!! This is a really simple concept that I hope even you can understand.

THATS why I was asking, you were coming across so hard and from such a different angle to most of the rest of us I wanted to know your "Frame of reference". I don't need to worry now, thanks for answering.

Si

[terminus mos]

DB

The resistance your are encountering on this thread is a result of your lack of understanding of the EC225 and technological milestone it represents. For those us us lucky enough to fly it, we understand that the considerable safety improvements in the avionics, AFCS and warning systems have been developed with the same technical capability and ethos of the people who are working to fix the problem right now. We know they will hunt down the problem and fix it. But it will take time!!

Er, it's a bigPuma designed in the 1960s albeit with another blade, nice cockpit avionics and powerful engines. It is barely Part 29 compliant (with some grandfathering) and, as demonstrated by the shaft failures, probably has too much engine power delivered by the fadec for the rest of the dynamics. It's serviceability and availability rate is poor and while pilots like it, passengers don't.

I guess the concept of luck is subjective.

[Pittsextra]

BigglesB - Of course I take you point although there is always a danger that one can make the mistake [in thinking] that their perspective is the only one but its limiting.

[DOUBLE BOGEY]

TERMINUS MO - Are you speaking from personal flight experience of the EC225 or just an opinion in general??

Technically speaking, the part of the shaft that is failing is not subject to any more torque than it was in the AS330, AS332, AS332L1 or AS332L2 as all it does is drive the MGB oil pumps. I am not sure torque is the root cause but this is a very ill-informed opinion as I am a Pilot and not a design engineer.

DB

[terminus mos]

DB

Flown many hours as PIC on the L and L1 and a few on the 225. Now I pay the bills. Our people didn't like the 225 much before these recent episodes, the Puma family generally was not liked after April 2009, especially so hard on the heels of Cougar, all helicopters were feared.

I spent many hours after REDL explaining the 225's outstanding features and the differences from the L2, trying to assure them of the integrity of the 225 MGB without trashing the L2's reputation. Now I am struggling to maintain any trust with passengers.

Whether I turn to AW (tail) Sikorsky (MGB) or EC (MGB) I find myself unable to offer reassurance. Now, passengers are over all things Puma and want the S-92, it's performance over the last 3 years has earned it some tentative trust.

[HeliHenri]

Hello terminus mos,

Whether I turn to AW (tail) Sikorsky (MGB) or EC (MGB) I find myself unable to offer reassurance. Now, passengers are over all things Puma and want the S-92, it's performance over the last 3 years has earned it some tentative trust.

You're quite right, nobody is able to offer reassurance. This AD is only few months olds :

One More AD for the Sikorsky S-92's Gearbox | Aviation International News (http://www.ainonline.com/aviation-news/ainalerts/2012-07-24/one-more-ad-sikorsky-s-92s-gearbox)
.

[Pablo332]

Double Bogey

Its probably not torque thats breaking the shafts. The shaft is subject to cyclic loads generated by the meshing of the pinion gear. These forces are greater then the previouse versions due to the 17% ish hike in power.

Edit due to spelling

[DOUBLE BOGEY]

TERMINUS MO - Ok I hear you and I do not want to bore you with the stats on the massive number of offshore flights compared to the incidents as just one is always too many.

In respect of the EC225, I feel we should make distinction between Operational Capability and Technical Serviceability. Of course they are two different things.

The EC225 has been designed with offshore safety in mind. As you have L, L2 and 225 experience you will know well the step changes in capability and safety enhancements that the L2 and 225 represent when compared to the L/L1, with each step being a significant move forward from the last variant.

[DOUBLE BOGEY]

PABLOS 332 - How do you know that? Are you a design engineer? Are you testing it? Have you got a strain gauge on it?? Come on lets at least deal in facts when it comes to the technical bits!!

[Pittsextra]

To be fair we do know:-

Before next flight, install a placard “MAXIMUM CONTINUOUS TORQUE LIMITED TO 70% DURING LEVEL FLIGHTS AT IAS ≥ 60KTS

” in full view of the pilots, in accordance with instructions of

Eurocopter EC225 ASB No.04A009 revision 2.


Because:-

Eurocopter have shown that crack propagation is slower with reduced Maximum Continuous Power (MCP).

[Pablo332]

Double Bogey

Which bit of my post has caused you the most offence?I’ll try to address it.

[DOUBLE BOGEY]

PABLO 332 - You are not causing offence but:

For example, you imply that there is more load on the shaft due to the higher torques through the box as a likely cause to the failure but this is not consistant with 8 years of trouble free operation!!

Like I said, how do you know the shaft suffers greater lateral loads??? My understanding, and I am far from a design engineer, is that this type of pinion/crown arrangement is self engaging and expressly designed to reduce the effect you describe...but like I said I am not an engineer.

Facts only are needed now.

DB

[HeliComparator]

As I understand it, the proposed reduction in torque is to reduce the propagation rate of a crack once it has formed, rather than to reduce the probability of the crack forming in the first place.

[Pablo332]

Double Bogey

It would appear that its sentence one and two that you take exception to.
The shaft is subject to cyclic loads generated by the meshing of the pinion gear.
This information was presented as a matter of fact to illustrate this section of the shaft is just not there to drive the oil pumps.
These forces are greater than the previous versions due to the 17% ish hike in power.
I’m not suggesting this is the cause of the current problems, but any load taken by the 2 roller bearings will be increased with an increase of power over the 332 instalation.

[Bravo73]

Doing so based on rumour and speculation (especially when it is untrue!) seems less meritorious.

Oh, the irony. :rolleyes:

[Pittsextra]

As I understand it, the proposed reduction in torque is to reduce the propagation rate of a crack once it has formed, rather than to reduce the probability of the crack forming in the first place.

So suggesting you fly on with known crack but at less torque?? From the latest AD.

EASA EAD 2012-025-E

If, during the MOD-45 reviews as required byparagraph (2.3) of this AD, the last MOD-45 record occurred more than 3 FHbefore the actual accumulated FH, before next flight, inspect the installed MGB bevel gear vertical shaft, for absenceof cracks in the area of the weld, byHFEC in accordance with instructions of Eurocopter EC225 ASB No.04A009 revision 2, and if any crack isfound, before next flight, replace the vertical shaft with a serviceable part

[HeliComparator]

No, to increase the safety margin if a crack forms in flight after the last M'ARMS download, as part of the justification for allowing 3 hrs flight between downloads.

[riff_raff]

Technically speaking, the part of the shaft that is failing is not subject to any more torque than it was in the AS330, AS332, AS332L1 or AS332L2 as all it does is drive the MGB oil pumps. I am not sure torque is the root cause but this is a very ill-informed opinion as I am a Pilot and not a design engineer.DOUBLE BOGEY-

While I understand the point you are trying to make about the modest amount of pump driving torque transmitted thru the lower portion of that shaft, in reality the torque transmitted thru the bevel gear mesh is what creates forces and moments on the shaft, housing and bearings.

I'd bet than when this issue if finally resolved, the one-piece welded shaft will be replaced by a two-piece shaft design with no welding. As always, just my humble opinion.

[terminus mos]

Henri

Your point on the S-92 AD is well taken, but our offshore workforce in the majority don't see the ADs and inner workings of the airworthiness systems.

The Union guys who do take an interest say that while the S-92 has and may still have a few issues, Sikorsky generally understands the problems and works on a fix while EC doesn't seem to fully understand the 225 (or L2) MGB problems.

The passenger perspective is that the expensive ($) new technology helicopters from an airworthiness point of view are less safe than some of the older generation aircraft and I find this a difficult argument to counter. Notwithstanding the "working but not indicating" EMLub, the concept of a safer gearbox to the workforce does not exist.

[HeliComparator]

TM, with the L2 and now these 2 ditchings, I suppose the workforces's feeling that you mention are not surprising. However I don't think the 225 is an intrinsically unsafe (or less safe) heli and if I did, I would be the first to not want to fly it. The trouble is that a generally well designed heli is only as good as its weakest bit, so if 99.99% is really good, there can still be a rogue bit that can cause a big problem.

I do agree that a brand new type may be less safe from an airworthiness point of view, than a well established type. However the current N Sea "new generation" aircraft are now 7 or so years old, so hardly spring chickens.

It is perhaps more relevant to consider what will be the next fatal accident. Yes, we all hope that there won't be one, but with 30yrs + of N Sea life left, that is quite a hope.

The sophisticated autopilots of the new types, coupled with good operating procedures and a proliferation of simulator training does make a "pilot error" type accident much less likely these days. That puts the focus onto airworthiness accidents, even if they are no more likely, and hopefully less likely, than before, they may again become the predominant factor in the accident statistics.

However, if I was a gambling man I would put money on the next accident NOT being related to a Super Puma family gearbox issue. By the time we resume flying it will surely have had more scrutiny than just about anything else! Something unrelated will come out of the woodwork on that or another type.

I am not sure if that is reassuring, but it is realistic! But for those of your colleagues unfortunate enough to suffer an untimely death, it will almost certainly not be due to a helicopter accident. Heli flying is really very safe.

[47B-3]

What is the status of the Era Helicopters EC225 fleet in the Gulf of Mexico and overseas?

[Colibri49]

riff raff (you aren't by any chance ex-RRAF, Royal Rhodesian Air Force? Riff-Raff was their sobriquet.) Anyway..............


"While I understand the point you are trying to make about the modest amount of pump driving torque transmitted thru the lower portion of that shaft, in reality the torque transmitted thru the bevel gear mesh is what creates forces and moments on the shaft, housing and bearings.

I'd bet than when this issue if finally resolved, the one-piece welded shaft will be replaced by a two-piece shaft design with no welding. As always, just my humble opinion."

Thanks for perfectly encapsulating the shaft issues for me. I would even venture, now that I slightly better understand things, that if there were no bottom bearing resisting the side loads, then there would be less stress on the weld as a consequence of the flexing/bending happening above the bevel gear between the other two bearings.

Yes. Right on! I vote for a new shaft without any weld, except that it would take years to certify.

[Fareastdriver]

Yes. Right on! I vote for a new shaft without any weld, except that it would take years to certify.

Except that the 332l has been flying with a welded shaft for over thirty years.

[Colibri49]

Of course. However in the 332L and L2, it was subjected to lower torque and consequent bending/flexing/vibrations?/whatever other manifestations of stress might exist.

The EC225 seems to have reached the limiting threshold for welding in this application.

(Edited to add this genius idea.) How about thickening and extending vertically the wall of the lower shaft, at the top where it meets the upper shaft, cutting a screw thread into both shaft sections with suitable radii to minimise stress risers and screwing the shaft sections together?

I think I'll apply to be a consultant for Eurocopter. All I'll ask is Euro 250k per annum and little perks, like a comfortable pension.

[jimf671]

Long bolting could be worth a look but screw threads on the component mess up alignment and are not useful with gearing.

[HeliComparator]

However, it is funny how the welded shaft was fine for the first 120 or so EC225 aircraft and 75,000 hrs just in the Bristow fleet.

[Droopystop]

However, if I was a gambling man I would put money on the next accident NOT being related to a Super Puma family gearbox issue. By the time we resume flying it will surely have had more scrutiny than just about anything else! Something unrelated will come out of the woodwork on that or another type.

HC,

I think you are a brave man to make such assertions. Maybe, just maybe all the Super Puma MGB issues are the symptoms of a more fundamental sickness. If so the regulatory/investigative diagnosis must be absolutely thorough. Otherwise EC will be reaching for the first aid kit when only major surgery will cure this malady. I desperately hope your feelings are based on hard fact not blind faith.

Colibri,

The day they let a pilot design a helicopter gear box is the day I stop sitting in one. Screw threads are for bottle tops, not holding shafts together.

[CopterDoctor]

Yes thats a puzzle... apart from the change in the countersinking of the hole -maybe they changed supplier ?

[FERetd]

Droopystop, quote " Screw threads are for bottle tops, not holding shafts together".

Or rotor heads?

[Droopystop]

FERetd,

How many heads are screwed directly onto the shaft, ie the axis of the screw thread coincides with the drive shaft axis and the torque is transmitted throught the threads?

[HeliComparator]

Droopystop, maybe they are all a symptom of fundamental sickness. Maybe the gearbox internals are made of cheese, just like the moon? Maybe a mouse got inside to eat the cheese?

On the other hand, perhaps you are just over-reacting to a very successful transmission design that has had 2 problems. One catastrophic (L2) the lack of an exact explanation for which does make me uncomfortable until I remember the 3 million flight hours that the identical design has flown without a problem, and that it probably wouldn't have happened if correct maintenance procedures had been followed. And recently, the other problem rearing its head which is non-catastrophic but we suspect the result of a design change. Hardly an indication of fundamental sickness unless you are determined to exaggerate the problem.

The S92 churning events were of similar severity to the shaft breakages, requiring an immediate landing. Ditto the vespel drive failures which required an immediate landing according to the RFM of the time. The difference is they didn't happen in UK waters and you have forgotten about them!
Clearly the gearbox is not perfect, but it is no more imperfect than any other helicopter.

[Variable Load]

Ditto the vespel drive failures which required an immediate landing according to the RFM of the time.

Sorry HC, but you are wrong. The S92 RFM has always had a Land Immediately requirement when the MGP Oil Px is below 5 psi. A single vespel spline failure/oil pump failure did not produce an Oil Px indication below 5 psi.

Also the first churning event produced a number of (startling) indications that resulted in the crew electing to carry out a forced landing, however it was not an RFM instruction but an airmanship decision.

[212man]

it was not an RFM instruction but an airmanship decision.

Correct insofar as the decision at the time was airmanship based, but actually with the smoke in the cabin the RFM did say "Land Immediately." You may recall that SAC wanted to remove that line subsequently!

Anyway, back to the 225.......

[Dry wretched thunder]

so what is being used now in place of the 225s, have the old tigers had a call up, sorry if this has been answered

[Adroight]

Well irony of ironies you know that Italian machine that had a tail boom that kept falling off? Well guess what? It is now doing a sterling job in certain parts of the North Sea flying up to 10 hours per day taking up the slack.

[FERetd]

Droopy, now you are just nitpicking.

The reason that your rotor head stays where it should is because of the friction provided between the threads of the "Jesus" nut and the main shaft. The torque is transmitted by the splines - but you knew that.

If, quote:- " screw threads are for bottle tops", try flying your helicopter without the "Jesus" nut.

Good luck!

P.S. The B747 trailing edge flap drives are of "bottle top" design - works well.

[HeliComparator]

FER - listening to too many urban myths! Jesus nuts are fitted to ancient teetering-head helicopters, not to modern articulated head ones.

[Droopystop]

HC,

I genuinely hope you are right and I am over reacting. If these three incidents are the only gearbox malfunctions ever experienced by the Puma family then I certainly am and stand corrected. All I hope is that EC catch all their mice so we can sit back and know the MGB is going to work every time, all the time. And that goes for every helicopter manufacturer.

FERetd,

As you point out the thread on the Jesus nut (although big helicopters have a lot more than one) doesn't transmit torque. Colibris solution appears to have a thread that transmits torque, just like a bottle top.

[HeliComparator]

VL, perhaps it was before you did your 92 course, but in 2005 before the Norsk vessel spline incident, this is what the S92 RFM said verbatim:

start quote:

MAIN GEAR BOX OIL SYSTEM FAILURE

Symptom:

MGB OIL PRES or MGB OIL HOT or MGB CHIP or ACC 1 CHIP or ACC 2 CHIP

CAUTION
The main AC generators are cooled by main gearbox oil. Loss of cooling oil may result in mechanical failure of the generators and loss of main electrical power.

Confirming:

Main gearbox oil pressure is less than 35 psi, or*
Main gearbox oil temperature is greater than 130 degrees.

Action:

1. Descend to minimum safe altitude.
2. APU - ON
3. APU GEN - ON
4. Land as soon as possible.

If the MGB OIL PRESS warning indicator also illuminates:

1. MGB OIL BYPASS switch - BYPASS

WARNING
BYPASS must be selected within 5 seconds after the warning indicator has illuminated to ensure an adequate quantity of oil remains in the gearbox. DO NOT activate BYPASS if the warning indicator is not illuminated.*

2. Land as soon as possible.

If MGB oil pressure continues to decrease or there are loud/unusual noises, unusual vibrations or progressively increasing power required to maintain flight:

3. Land immediately.

end quote

So, pressure falls below 35 psi, button is pushed, pressure continues to decrease down to a little over 5psi ("continues to decrease" being the operative words) then it is land Immediately. The mention of 5 psi was only added after this event.

[SASless]

HC.....could we avoid going back through another rehash of bashing the 92 and just stick to the issue at hand. The 225 MGB problems has effectively grounded the aircraft, destroyed faith amongst its passengers, and caused a hell of a disaster for the Operators and Customers.

The cause of the problem, the cure for the problem, and whether the reputation of the 225 can be salvaged....are what needs to be discussed.

We are not here to compare the 92, 225, and 139 to each other.

We are here seeking answers to the problems extant for the 225, EC, and the Operators.

I know it must be annoying to see the 92 prevail over the 225 as you certainly had a lot of "stock" in the 225 and spent a great deal of time talking down the 92 while extolling the many virtues of the 225 as you saw them then.

So....when can we expect to see some resolution of this problem with the 225 MGB? What effect has this had on the Operator's profitability? Are the Operators going to file suit against EC? What is EC's Liability here? How bad has the damage to the 225's reputation has occurred? Tell us your thoughts on those issues and leave off harping on the 92 please.

[HeliComparator]

SAS, yes I agree it seems to be going off topic, but my point is that although the spotlight is on the 225/L2 at the moment, it has also been on other modern types such as the 92 in the past for events of the same severity. In part the spotlight was less bright because these events didn't happen in CAA-land.

Yes I am saddened to see the 225 taking a beating because I know just what a good aircraft it is, always accepting that all helis have their issues including this one! But those specific issues aside, it is overall a really good pilot's machine with better range/payload than the competition.

It's interesting to review the S92 EOP and see just how clunky it is compared to the Super Puma family.

Anyway, regarding your specific points yes it is bound to affect profitability in the short term. I suspect that EC's liability in law goes no further than the purchase cost, since consequential losses are always excluded in sales contracts. You wouldn't buy a new car and then sue the manufacturer if it broke down on the way to work and you lost a day's pay.

Yes it's reputation has obviously suffered but hopefully this is only a short term issue and in 5 years time it will all be forgotten, just as its competitors' major events have been.

As to resolution timeframe, I know no more than you do which is that the current thinking is February.

[Sevarg]

HC Just like the Chinook after Sumburgh?

[victor papa]

How is the EC725's affected? Are they also grounded/limited/etc? Have they had any incidences? Just wondering as it could be interesting if they are still flying?

[JohnDixson]

HC,

The procedure you quoted "verbatim" is missing three items in my copy of the original RFM approved by the FAA 9/11/04:

There were two explanatory notes following the Warning in para 1.

There were two Land Immediately paragraphs, number 3 and 4.

Perhaps there was a revision between the original and the one you quoted?

Thanks,
John

[HeliComparator]

John, possibly. When I cut that out in 2005 I didn't cut anything from within the quoted area, so perhaps your bits are outside the quoted area? But if within, I would say there must have been a revision in the mean time

Sevarg, no hopefully not like the Chinooks. They died because of the fundamental design issue ie intermeshing rotors, plus a lot of deaths. The 225 has yet to kill anyone and if you are a passenger, I suspect that is the major consideration.

[SASless]

Odd.....the old girls are still flogging the skies around the World with fleet hours in the Millions....and a safety record as good as any other helicopter. The North Sea machines that got flogged off are still out there earning a living hauling massive loads all day long for Columbia.

You suppose if the Brits had listened to those who had operated the things for decades before the first one arrived in Blighty....things might have gone a bit differently? I should think the continuing success of the Chinook in other parts of the World and the RAF.....should confirm the validity of the design.

Some folks just have a narrow minded view of things.

They died because of the fundamental design issue ie intermeshing rotors, plus a lot of deaths

[HeliComparator]

SAS, OK happy to change that to "fundamental design issue ... in the eyes of pax and oil companies".

[albatross]

Well if the two 225 ditchings had happened in different sea states without S+R close at hand they may well have killed a lot of good folks.
I put that down to good piloting skills, adherence to check lists, and more than a little bit of luck.
I don't think that the passengers are comforted to any great extent just because of the good outcome of events in the two cases.

"In part the spotlight was less bright because these events didn't happen in CAA-land." Come on HC that's a little bit over the top don't you think! Not all of us work in CAA land and the CAA is not the be all and end all of helicopter safety.

[HeliComparator]

albatross, yes the sea states were good but they have to be pretty bad before fatalities become probable rather than possible. There are certainly such days but the vast majority of days are not like that. And as I said, exactly the same applies to other type's non-catastrophic events resulting in "Land Immediately"

[JohnDixson]

No, HC, they were in that section of para. 7.1 that begins with: " If the MGB OIL PRESS warning light illuminates...

The second Land immediately action, sub para 4 within the section you quoted, is the last entry in the general para. 7.1.

Thanks,
John

[albatross]

A quick google search on "helicopter ditching statistics":

http://ftp.rta.nato.int/public//PubFullText/RTO/AG/RTO-AG-HFM-152///AG-HFM-152-05.pdf

Interesting read amongst many others.

Of course we know that are "Lies, damned lies and statistics" LOL

Interesting thread - I think we may be headed for a record number of pages.

Cheers
Albatross

[HeliComparator]

albatross, as far as I can tell that doc doesn't really distinguish between intentional controlled ditching, and accidentally flying into the water. At first glance, that devalues the research in my eyes.

[Variable Load]

Albatross, I have seen this document quoted a number of times and as HC highlights, it does not limit itself to controlled ditchings in reaching the supposed survival rates. I would go so far as to say the document is dangerous, as it does not present pilots with the true risks associated with a controlled landing on water.

I have always wondered if the Captain of the Cougar aircraft, who ignored the Land Immediately situation the aircraft was in, had seen this document and these statistics were part of his decision making process?

A quick aside - HC, the S92 RFM I was referencing for my earlier response was dated November 2005, obviously an amendment after the incident you are referring to.

[albatross]

Good point guys.

I wonder also if those stats influenced the crew off of NFLD.

The weather/ sea state and temperature at the time was far from ideal.

I found another site in my quick search that posted some truly horrific stats which I will not quote here as they seem more scare mongering than anything else.

Like anything else on the internet the application of a little bit of salt is required.

Cheers
Albatross

[SASless]

Seems the 225 is doing that salt thing really well!:E

The stats do force us to consider the effect Sea State, Water Temp, Amount of natural light (Day-Night), Visibility, and response time of SAR in their effect upon Air Crew Decision making.

Ditching in the Bahamas is not the same as ditching north of Deadhorse or in the North Sea or off Newfoundland.

[terminus mos]

HC

Yes I am saddened to see the 225 taking a beating because I know just what a good aircraft it is, always accepting that all helis have their issues including this one! But those specific issues aside, it is overall a really good pilot's machine with better range/payload than the competition.

But sadly the passengers never did like it much and now don't want to go near it. My company is being pressured to replace them with 92s, memories are short it seems. But, the 92 has been doing better recently.

[HeliComparator]

terminus, there are also plenty of stories of passengers routinely using the 92 not liking it either. Let's face it, the offshore community just don't like any helicopters, and why should they when we scare them sh**less by showing them scary videos before each flight!

I suspect it is "grass is greener" but no less unfortunate for the future of the 225 at least in the short term.

[riff_raff]

Yes. Right on! I vote for a new shaft without any weld, except that it would take years to certify.Colibri49-

While EC apparently seems comfortable with EB/laser welding finished gear shafts, I know that other transmission OEMs prefer not to use this approach. The problem is that since the weld is performed after heat treatment of the gear, the metallurgical properties in the weld HAZ (heat affected zone) will remain in the as-welded condition, which is not optimum. The weld HAZ cannot be improved even with a thermal stress relief and normalization cycle.

If the reports of weld failures are true, even if EC retains the welded shaft design (with any necessary design changes) then there will still be a lengthy re-qualification process. Since the gear shaft is a flight critical component, the weld process itself and any post weld QA procedures (such as NDI, etc.) must also be re-qualified.

I appreciate why EC chose to use a welded bevel gear shaft design. And that is because it is definitely lighter than the conventional 2-piece mechanically fastened design approach, as well as being less expensive. However, there is a very good reason many OEMs still use the 2-piece design, and that is because it is very difficult in a production environment to ensure the extremely high quality levels needed in the welds.

Here is a link to a drawing of an older MGB design (http://www.huey.co.uk/images/history/techsheet6.jpg) (I believe it's a Huey MGB) that has a similar layout to the EC225, with a spiral bevel input gear stage. You can see how the spiral bevel gear is mechanically fastened to the shaft. While it may seem counter-intuitive, from an overall fault-tolerance standpoint this design is actually better than the EB/laser welded design. Since it is an easier QA task to verify the correct installation of fasteners than it is to verify the integrity of an EB/laser weld joint.

Very interesting discussion! I've even learned a few new things.

[Colibri49]

riff raff

As before, your explanations make perfect sense and strengthen my first gut reaction in the days after the May 2012 ditching when I was astonished to learn that welding gets used in such an application. To put it simply "It just don't seem right".

This part of the EC225 gearbox is probably approaching the limit of horsepower/torque/vibration stresses that this latest version of the Super Puma family can tolerate. Something changed in recent times, perhaps caused by V12 software, to push things just beyond that limit, I guess.

But I very much wish to see the EC225 back in business soon. So if my whacky idea of threading and screwing the shaft sections together is a non-starter, what about the suggestion from jimf671 "Long bolting could be worth a look" ?

Not only would this clamp the lower shaft section safely in place, but it seems to me that it would create two redundant load paths; the weld and the long bolt. I like "belts and braces" as a principle.

[DOUBLE BOGEY]

ALBATROSS - your comment about luck alluding to the forced landings in calm sea states is not an accurate reflection of the Puma design's inherent ability to float. Throughout this issue I have come across a couple of good images of Pumas floating quite happily in fairly unpleasant sea states. One in the Norwegian sector and Bristows Tiger after the lightening strike. (I think the Tiger rolled over only after the salvage boat stabbed the floats).

It floats low in the water but it does seem to float well so I do not think your point is valid.

DB

[albatross]

Well years ago I had the engine of a Bell 206L self destruct in a most unexpected and spectacular manner.
I had just spent 40 minutes inserting crews into 3 confined areas in the bush and had just departed camp to return to the area with the second crew over unbroken forest and small lakes.
When Mr. Turbine resigned I just happened to be nearly overhead an abandoned sandpit into which I was able to do a successful 270 auto thanks to the 206L doing that so well.
In my case I call that luck - 206 auto rotational capabilities and the good training I had received notwithstanding.
When I refer to luck in this case I call the good sea state and proximity of rescue vessels the same thing.
I in no way try to take away from the professional conduct of the crews or the seaworthiness of the 225 when ditched.
I just think that it could just as easily have happened to another aircraft, elsewhere, in a worse environment. Hence luck, fate whatever you want to call it playing a roll.

[SASless]

Yet....does not the UK CAA encourage "Side Mounted" flotation to ensure the helicopter stays at least mostly upright? The majority of drownings post-ditching/crashes comes from the aircraft rolling over and filling with very cold water.

I know they did lots of expensive testing to confirm that notion.

[JimL]

The work still continues but now under the auspices of EASA.

No, the intention is not to keep the aircraft in an upright position - with the high C of G that is almost impossible - but to ensure that it reaches a predictable position, with an air cavity, so that escape is possible for a reasonable period.

It can also be used in addition to conventional floatation bags should the sea conditions be benign enough to permit a dry escape.

I agree with the poster who said that there was a great deal of luck involved in these ditchings; had they occurred on the extensive period of time when the sea state is greater than SS 4 there might have been a different outcome.

Well done the crews in both incidents.

Jim

[HeliComparator]

Hi Jim, why do you say SS 4 as opposed to SS 6, which the EC225 floats are demonstrated at?

[SASless]

http://www.easa.europa.eu/rulemaking/docs/research/EASAfinalreport.pdf

For those who like pretty pictures and loads of data.


Some thought about unintended consequences needs to be done.....for you Bell 212/412 Pilots....imagine getting out of one of them if it were laid nicely over on its side! For a well seat passenger on the bottom....bad news. For the Well seat passengers on the top...no problem. For the main cabin gang....where would you put the step ladder?

[HeliComparator]

For the record, I have never been in favour of the side floating concept but CAA were determined to go ahead with the research anyway. Nothing wrong with research but as SAS says, the unintended consequences need to be carefully considered, such as unintentional inflation in flight and the decreased upright stability resulting from more mass high up, and increased windage.

Remind me, when did the last Super Puma family aircraft make a controlled ditching and go upside down before everyone got out? Of course there was the N Cormorant uncontrolled arrival in water, but not sure if the extent of water impact damage and g forces would have allowed a greater survival rate if cowling floats had been installed and had automatic inflation. That was 25 years ago of course.

[industry insider]

HC, G TIGH 14th March 1992, more like 20 years.

[HeliComparator]

Thanks II, for some reason I had it in my head it was 1987.

[John Eacott]

http://www.easa.europa.eu/rulemaking/docs/research/EASAfinalreport.pdf
Some thought about unintended consequences needs to be done.....for you Bell 212/412 Pilots....imagine getting out of one of them if it were laid nicely over on its side! For a well seat passenger on the bottom....bad news. For the Well seat passengers on the top...no problem. For the main cabin gang....where would you put the step ladder?

SAS,

That was (supposedly) dealt with after the 1978 Bell 212 rollover on Nordraug in the Brent. The legs of the rear seat row are supposed to be marked and used as a ladder to climb up to the top door.

But maybe that bit of 'Corporate knowledge' has been lost in the mists of time?

[Bravo73]

Air Accidents Investigation: S7/2012 - EC225 LP Super Puma, G-CHCN (http://www.aaib.gov.uk/publications/special_bulletins/s7_2012___ec225_lp_super_puma__g_chcn.cfm)

Summary:

This Special Bulletin contains information on the progress of the investigation into identifying the cause of the 360º circumferential crack in the bevel gear vertical shaft on G-CHCN (AAIB Special Bulletin S6/2012). It also compares the findings with those recorded previously on another EC225 LP accident involving a similar failure on G-REDW on 10 May 2012 (AAIB Special Bulletin S3/2012) and provides a further update on the investigation into both accidents.

The Chief Inspector of Air Accidents has ordered that the investigations into the accident to G-REDW on 10 May 2012 and to G-CHCN on 22 October 2012 be combined, and to publish an Inspector’s Investigation Report.

[Pittsextra]

Looking at the HUMS data anyone have an idea about the thresholds?

What I don't understand is how the EC defined maximum values have been calculated for the fleet. How can these be set so far away from the "real" learned thresholds (as you can see from the data of CHCN and REDW) - is the variance so marked across the whole fleet that you might see other EC225's operating and thus the need for such vast headroom?

The next query is around the actual learned amber threshold difference between CHCN and REDW for MOD45. REDW seems to have a threshold twice that of CHCN, now given these are "learned" what changed, because the data you can see plotted would not suggest the logic with these systems is the same.

Finally how do you reconcile the data you can see here with EC's recommendations post REDW?

[SASless]

John,

But then we also learned about the cabin floor mat that floats up as did the foam seat cushions

[liam225]

What's happened to g-redw and chcn? Scrapped?

[riff_raff]

Bravo73,

Thanks for the report link.

It was interesting to learn why the 4mm hole was drilled into the weld joint. With the circumferential EB/laser type weld used on the bevel gear shaft, even though the process is highly automated there can be a small metallurgically deficient area right where the weld starts/ends. The reason there can be problems at the start/end point of the weld is this point is subject to fairly rapid heating/cooling as energy input from the EB or laser starts/stops. The metallurgical deficiency can take the form of small cracks, hot tears, cold laps, seams, etc.

The report does not come to a conclusion about what caused the initiation of the cracks, but it does show a fair amount of surface corrosion around the ID of the shaft. It's a bit unusual to see surface corrosion on the internal components of MGB's any more. It is standard design practice to use desiccant breather systems on MGB's, which are very effective at removing moisture from the air volume inside the housing. However, I don't know if this particular MGB used such a breather system.

Lastly, it was also interesting to read that the design and material of this particular bevel gear was changed to use a nitride case hardening process instead of carburizing. It's unusual to use nitriding for a spiral bevel gear because the case thickness is typically far less than with carburizing. Also, the hardness of the nitrided case drops off rapidly away from the surface, so the hardness of the remaining surface after finish grinding can be less than optimum. Spiral bevel gears tend to have high flank contact stress, so case hardness and depth are important for fatigue life.

Sorry if my posts are boring to some of you, but I find the topic of gearbox design very interesting.

[Savoia]

Sorry if my posts are boring ..

Riff Raff: Your aeronautical and engineering perspectives are always much valued and provide welcome reading.

[Alien Woe]

Marine Transfer Workgroup established
Wed 21st November
Step Change in Safety has established a new workgroup, focusing on the safe transfer of personnel offshore by means other than helicopter.

Due to the exceptional circumstances with a number of Aberdeen-based helicopters still suspended and impacting on the logistics of getting people on and offshore, transferring workers by other means – such as frog and walk-to-work – remains an option when helicopters are unavailable.

The new group, co-chaired by Bibby Offshore’s David Forsyth and BP’s Colin Gay, will initially look at pulling together existing guidance and information. This will arm companies with the facts to help them safely plan transfers and will help the workforce better understand what is involved should they agree to be transferred this way.

Marine transfer is commonplace in many parts of the world. Many of the global companies which carry this out elsewhere in the world are also based in Aberdeen – therefore there is an existing base of expertise and knowledge, despite the practise being less common in the UKCS.

The group, which will run until the helicopter situation is resolved, is looking for involvement from elected safety representatives. Anyone interested in joining the group should contact Step Change in Safety at [email protected] or phone 01224 577268.

It seems the North Sea oil companies are planning for a shortage in helicopter capacity for quite a while. Hope their new transport arrangements don't become permanent :(

[bondu]

terminus mos

Thirdly, industry will never again relay on having a dominating type of helicopter. EC225s will be swapped for S-92s to reduce the risk of business disruption such has occurred since the grounding.


Isn't that happening right now? The S92 is now the 'dominant type' on the North Sea.

bondu

[SASless]

riff raff......you just keep boring us please....as some of us need an education on topics you are an expert on!

[bigglesbutler]

riff raff......you just keep boring us please....as some of us need an education on topics you are an expert on!

Seconded.

Si

[dascanio]

Riff Raff,
To add some bits to your post:


- nitrided depth is smaller than carburized depth, thus preventing, usually, the final grinding of big spiral bevel teeth, as you posted
- however, nitriding steel has some benefit, because, for instance, the nitriding process causes less distortion during heat treatment respect to carburizing, thus it is a good choice for big ring and helical gears.
- 32CDV13, on the other hand, is a bit peculiar, because combines the advantages of high core strength and the capability for deeper nitriding depth respect to classic nitralloys. With higher case hardened depth, you could grind a big spiral bevel teeth without encountering the difficulties you highlighted in your post. I imagine this is the rationale behind this change of material on ec225.

Anyway, the gear teeth are not particularly in discussion, they didn't fail, the shaft failed!

[Hummingfrog]

Perhaps it is time for CHC to bring its 365N2s out of retirement. Boat the oil workers to within a couple of miles of their destination then shuttle them onto the rigs.

It worked in the 40s/Piper/ETAP for many years and gets round the tricky transfer from the boat to the rig.

Plenty of shuttle qualified pilots about who would be willing to help out in these difficult times!

When not on holiday of course;)

HF

[Alien Woe]

Riff Raff,

I love education bro, and ur posts are educational - keep the info coming :ok:

[The Sultan]

Keep the posts coming Riff they are mostly accurate and informative to the vast readers of this thread. If some here do not understand them that is their problem.

The Sultan

[Alien Woe]

Riff Raff, Sultan,

You rock :ok:. Please keep up the questions and information from guys who seem to have no ax to grind but want pure information. I'm mostly a 'lurker' but I love the way that so many guys here just ask relevant questions in an attempt to get relevant answers :ok:

[Pittsextra]

Talking relevance - top of page 5 latest AAIB report, the cracks started and grew to failure in areas of the shaft that had not nor were required to be surface hardened.

The shaft on the CHC machine was it would seem from the latest AAIB report likely to be the highest time shaft on any 225...

That and the question mark on the use and function of HUMS which is now something of focus - EC don't look the smartest frankly.

[HeliComparator]

Pitts, on the subject of shaft age, I'm not sure why you suspect it is particularly old. The first Bristow machines were delivered in 2005 so their shafts were probably built in 2004 so would be close to twice the calendar age. Whilst CHC overhaul their own MGBs at HeliOne (and so get the same shafts back from overhaul) Bristow uses power-by-the-hour so without checking the log cards I couldn't be certain that we have older shafts, but I would strongly suspect so.

[Pittsextra]

HC - Hi. The latest AAIB report says that no EC225 shaft had covered 4000 hours and that the shaft fitted to CHC's machine had 3800 or so. (sorry don't have the report to hand to give exact number). So on the basis nothing has got to 4000 and the one in the sea in October was 3800...

One thing I find incredible with story is how some of these odd decisions are almost accepted.

You have some guy fly a Gazelle into a hill or some private owner suggest a new crazy scheme and everyone scoffs or calls everyone involved stupid etc.

Yet here you have one of the biggest manufacturers make at best questionable decisions with so far little insight to what testing has been done and the silence is deafening. I mean the latest AAIB report suggests part of the ongoing investigation is around the suitability of the material selected.. Really?!

[HeliComparator]

Oh yes, it does say that no shaft has exceeded 4000 hrs which is a bit surprising. Our oldest airframe must be pushing 10,000 hrs by now so I suppose it must be just the PBH thing has meant that these older airframes happen to have younger shafts in them.

[Pittsextra]

When this shaft is lifed at 20k hours and airframes with 10k hours you might think you would still have shafts older than 3845hours?

although makes you wonder where the 20000 hour life number for this shaft comes from...

[riff_raff]

....Anyway, the gear teeth are not particularly in discussion, they didn't fail, the shaft failed!..... dascanio,

Your point is valid, but there still may be some questions about how the change in material and processing made specifically for this model MGB may have affected the weld quality.

For example, with carburizing (ie. the process used prior to the EC225) it is standard practice to mask off any surfaces that are not to be case hardened using copper plate, and then the copper plate masking is removed after carburizing. Also, since there tends to be quite a bit of quench distortion with carburizing, especially in areas with thin cross section, the carburized half of the shaft would likely be 100% machined around the weld joint surfaces after heat treatment to provide accurate fit-up for the weld joint. This post heat treat machining operation would remove any surface contamination and providing very clean material for welding.

However, with nitriding (ie. the process used for the EC225) it is common practice to nitride the entire surface of the part. While masking (tin or copper plate) can be used with nitriding, this step is commonly eliminated to save cost, and also because the nitride case can have a beneficial effect on fatigue. Another very important processing step that must be taken after nitriding is removal of the thin outer "white layer". This white layer is composed of iron nitrides, and is very brittle and full of microfractures. It can be removed through mechanical means such as grit blast, or by chemical etching. Given the presence of surface corrosion on the inside surface of the shaft, and that the shaft fractures initiated from the inside surface of the shaft rather than the more highly stressed outside surface (as one would expect for a typical reverse cyclic bending failure), it seems conceivable that the weld integrity may have been compromised by contamination left behind on the inside shaft surface after nitriding/heat treatment.

As always, just pure speculation on my part. But that's what makes these forums fun!

[dascanio]

Riff Raff:

Thanks for your interesting posting.

I agree with your general comments on differences on carburizing vs nitriding.
Actually, as you pointed out, we are speculating, because we do not know the actual process applied on the subject gear .

Anyway, on my similar personal experiences, I have seen that on vital parts:

- the "white layer" is removed, with one of the methods you listed
- copper plating is used to mask areas not to be hardened

As far as the weld is concerned, I imagine that in any case the two mating areas of the two "half shfts" are machined to provide a correct match and a good clean diameters and planar surface before welding, tolerances at this stage are usually too tight to leave them as they are.

[Pittsextra]

I agree with your general comments on differences on carburizing vs nitriding.
Actually, as you pointed out, we are speculating, because we do not know the actual process applied on the subject gear .

Yes we do - just read the AAIB report.....

[bigglesbutler]

I agree with your general comments on differences on carburizing vs nitriding.
Actually, as you pointed out, we are speculating, because we do not know the actual process applied on the subject gear .
Yes we do - just read the AAIB report.....

Carburising for the "old" style shaft fitted to AS332L (and some L2's??) and Nitriding for the EC225, hence the discussion on the merits of the two techniques.

Si

[Pittsextra]

When at the top of page 5 in the latest AAIB report says:-


On G-REDW and G-CHCN, the cracks initiated and grew to failure in areas of the vertical shaft that had not been, nor were required to be, surface hardened.


So perhaps its more valuable to discuss the material used ahead of the hardening process.

[DOUBLE BOGEY]

PITTS - I see no value in you discussing anything in relation to the metallurgy of these components. You think you know what you are talking about......and that makes you dangerous!!!

DB

[Pittsextra]

DB - I see this is fitting the usual pattern which is we all become 10 years old again and run around calling each other names. Well done.

The thing is you have no idea who I am, what I do, what I have done. It is a joke to call me dangerous when frankly Sir it is you who likes to give it the big one around all your flying hours, your airmanship, risk management and yet where was your risk management, your airmanship around the flying of the EC225?

[bigglesbutler]

Pitts are you J Ferguson in disguise as you seem to be rubbing more and more people up the wrong way. So pray tell what IS your background's apart from a PPL holder?

Si

[Pittsextra]

As you wish biggles. It seems to me the people getting stressed are in a camp labeled "vested interest".

Sorry the point about being a PPL holder is? Is that supposed to a jibe or a sneer?

Tell you what take it I have zero hours, didn't go to a decent uni, no professional career, no funds and no experience in anything.

So you educate me on how surface hardening (lets call it nitriding) affected this shaft. Then once you have done that perhaps explain that HUMS data and then put the cherry on the cake and tell everyone how everyone seems comfortable when the shaft that failed in October was almost certainly the highest time on any EC225, and again to quote from the AAIB report, no EC225 shaft has flown 4000hrs - when EC love to trot out the 250000hrs statistic which is relevant how?

[bigglesbutler]

Pitts you've missed the point, you may be a mettalurgic genius and if you are pray enlighten us as those who have done so receive praise (par example riff-raff).

You come across as a know it all who actually knows nothing about the aircraft (from experience not reading tinternet/books etc), the environment we work in or the job we do. It's not a big deal to not know until you pretend you do and then it comes across very poorly.

I am a pilot, not an engineer, nor a chemist who knows metallurgy, but I have a technical mind and can absorb wise words from people who are far smarter than me. Hums is a tool, material hardening is a tool, the interim reports are just that and I am awaiting many of the answers you seek. I am however using my own experience and judgement to WAIT for those answers because they will come, our industry is far too controlled for them not to. Your constant stirring is simply starting to annoy me and others, so this will be my one and only attempt to explain myself to you. If you wish to continue trolling then feel free but by doing so you will reduce the number of people willing to converse with you.

Have fun.

Si

[Pittsextra]

I'm not sure how I have pretended to be an expert in anything have I? I've been free and actually very quick to tell all that I hold a PPL and I am not an ATPL EC225 pilot - for example. Except in doing so that seemed to suggest to some that my terms of reference were some how lacking - as you seem to be doing here.

I'm not interested in receiving praise, I'm not interested in trying to compare my flying experience with anyone, my education or my background because where does it lead? Do I have to scan my qualifications, take a picture of my aircraft, the house I bought with my experience in whatever? As I said its like being at school.

My interest in this is nothing to do with trolling but because I have a friend who was/is a user of this industry in the course of his work. Now obviously I agree the ultimate report will reveal all and we all wait to see what that outcomes that brings.

However waiting did not serve people all that well in this case did it? A lot of flight hours passed between 10th May and 22nd October and of course people take the decisions made by the operators and Eurocopter in good faith because why not? At some point in the future Eurocopter are going to say the EC225 is "fixed" and you are going to have to take that in good faith - again.

It is therefore surely reasonable to question the decisions made to date?

I'll give you an example. Look at page 3 of the latest AAIB report and figure 1. It shows the "learned" thresholds for alarms of a sensor called MOD-45.

I look at that data and I'd say that the mean plots for G-REDW were generally lower than G-CHCN and yet the learned Amber threshold is what? twice that of G-CHCN?

Now this HUMS data is something that is being used to give greater freedoms now in terms of flying the EC225 and will no doubt be used to give comfort in the future. Yet there seems to be absolutely no clear picture around these thresholds learned or indeed the fleet maximums.

Then combine that with the life of the shaft in G-CHCN and the stated on going work into the shaft its material and suitability for use in the future and how can you see these genuine and obviously concerns to be "trolling"??? Maybe you can have that conversation with my mates wife and see how casually she takes this.

I've got no beef with you or anyone else here and if my posts on this subject upset anyone then thats surprising given they are driven by safety.

Edited to add:- Biggles/DB you guys call me out and suggest I have no knowledge so how do you see things at this point?

[Brassed Off]

Pittsextra and others attracting unnecessary attention.
I personally think the days of this forum living up to its handle are long gone. ATPL, CPL, CFI or any other professional qualification seems to no longer be required on PPRUNE.
Just because some of us do have the "required" paperwork to seemingly qualify to post on this forum, does that mean we know more about machines and their construction? I have flown the EC225 now for five years. I am now converted to the S92 because of the recent events.
PPRUNE will not change the world so lets please keep up the food for thought without resorting to the old ticket holder arguments.
I would like to read all posts from whoever they are from, and make my own mind up from the contents of the posts.
I appreciate this sounds a bit stupid when I am commenting myself on others posts but I do not want anyone to feel pushed away.
Live and let live! Pittsextra, I find your posts very interesting and I am sure other layman like me do also. :) Please keep your thoughts coming because one day you maybe able to say "I told you so" and that will shut a few up.
Thanks.

[rotor-rooter]

Does this issue affect all variants of this model, including the EC725?

[DOUBLE BOGEY]

PITTS - The point is many of us here do have a VESTED INTEREST. To some of us it is our livelihoods, to others it is their method of transport to and from work. To the rest of you it amounts to rubbernecking and speculation. There is none so dangerous as he who has nothing to lose.

I do not mind at all your speculation about the nature of the failure and the technical content you seem desperate to impress us all with. What p***ses me off is your childish suggestion that one the great helicopter manufacturers in the world (and there are a few) knows less about the technology than you, or worse, is trying to pull the wool over our eyes.

BRASSED-OFF - Keep the faith buddy. Times are about to change...again.

DB

[cyclic]

Pitts, you keep delving into the reports. One of the great things about being here in the UK is that you can bring what you may think are injustices to light without fear of prejudice. You may or may not be right but you may just bring something to the surface that is worthy of consideration. We still don't have a definitive explanation to G-REDL (HUMS arguments aside) and after G-REDW it was largely assumed to be a one company issue until one of the largest helicopter operators in the world has the same issue. It does appear that in the helicopter world, we have to have confirmation of an accident by having another before things change.

We all have something to lose here, if the 225 doesn't return to service promptly, some here have more to lose than others. We will just end up with a fleet of S92s and a few shagged out L2s and the next thing that happens to either brings us back to square one.

I think most people can make their own judgement as to the efficacy of your posts, that includes passengers and crews - we don't need to be told how your missives should be read.

By the way, I have met a few PPL holders who are complete idiots; I have also met a considerable amount of ATPL holders who fall into the same category - that's life. A lot of ATPL holders were PPLs! There are very few ATPL holders that I would let run my business though...

[Old Age Pilot]

The thing is you have no idea who I am, what I do, what I have done.

And we don't care. But that doesn't have anything to do with the fact we have read your 200 odd posts and from that alone can tell what kind of a person you are.

As you wish biggles

You still didn't enlighten us - well, other than the 10 year old tantrum response...

Tell you what take it I have zero hours, didn't go to a decent uni, no professional career, no funds and no experience in anything.

Sorry the point about being a PPL holder is?

There is no point. That's just your green perception of what BB was asking.
However there is something to be said when a non-professional comes on here and starts shouting his mouth off in a non-professional way and helps create material for the many journos that scour this site for juicy gossip. Correct me if I'm wrong here, but this is in no way helping any of us in our industry. I'm sure if we were to come into your banker's forum (just a guess that you are a banker, maybe my old salt perception) and start mouthing off, ringing the dinner bell for the press and damaging your industry, you'd have something to say with regards to our "professional" connection to the industry. It's not the PPL that we sneer at. It's the non-professional attitude of the holder that is the problem. Have some humility and get over it.

It seems to me the people getting stressed are in a camp labeled "vested interest"

:D Congratulations. You stumbled over the exact point of this thread - and fell right on the very concern to most of us on pprune.

Pittsextra and others attracting unnecessary attention

Couldn't of said it better myself. This is what I tried to say on another thread about the Met Police and noise - started by another jumped up little person with something to prove!

It all comes down to attracting unwanted attention. Constructive discussion is one thing, but being a motor mouth is damaging to our industry - think Jim Ferguson.

Pittsextra; you are officially ignored!

[DOUBLE BOGEY]

Cyclic.

Nobody cares what licence anybody holds. That has nothing to do with my view of PITTs and his postings.

But just to balance the argument somewhat, I suspect your distrust of ATPL(H) holders may be borne out of their inherent desire to put SAFETY FIRST - always!!! And this may not suit they way you run your business.

But if you are actually involved in real aviation you may like to take a few moments to ponder the impression you have tried to paint to all who read this forum of your personal view of professional pilots. Your statement is digraceful!!

Please let me know what Company you run so I can note never to apply!!

DB

[bigglesbutler]

There is no point. That's just your green perception of what BB was asking.
However there is something to be said when a non-professional comes on here and starts shouting his mouth off in a non-professional way and helps create material for the many journos that scour this site for juicy gossip. Correct me if I'm wrong here, but this is in no way helping any of us in our industry. I'm sure if we were to come into your banker's forum (just a guess that you are a banker, maybe my old salt perception) and start mouthing off, ringing the dinner bell for the press and damaging your industry, you'd have something to say with regards to our "professional" connection to the industry. It's not the PPL that we sneer at. It's the non-professional attitude of the holder that is the problem. Have some humility and get over it.

Thank you for putting it better than me, perhaps I was trying to be too nice by not saying straight out.

ANYWAY, back on topic, so far we have a few interim reports that DO seem to raise more questions than answers. There is an obvious reliance on HUMS which in my mind is simply a tool that we must use, and the chemists are looking at the materials used. What more can we say, riff-raff has enlightened us on techniques used, till we get more information from the authorities.

My understanding of a learned limit on HUMS is that the machine monitors and measures the vibration. For a "good" aircraft the data will show a trace that will be different to a "bad" aircraft, and over time as more data is gathered and a comparison across the fleet is made the system "learns" what is a good trace and what is bad. Simplistic perhaps but I THINK that is all the learned limits are, nothing more sinister.

Si

[DOUBLE BOGEY]

BB - My understanding is the "Learned" limit is applicable only to the individual MGB/AC configuration. As this is established, threshold limits are then correspondingly applied in consultation with the manufacturer.

Maybe a HUMs engineer can confirm this or Helicomparitor might know!!

DB

[bigglesbutler]

DB I would imagine the "learning" would be useful across a fleet, for example the EC225 data could be compared across those, the L2's alike and then the L alike. Whether there would be the ability to compare data from a 225 to that of the L2 I don't know, but surely as more hours are flown on each type there will be more data and more comparison possible within each fleet?

I have just re-read your post and I THINK we are both saying the same thing :P

Si

[industry insider]

Cyclic

We all have something to lose here, if the 225 doesn't return to service promptly, some here have more to lose than others. We will just end up with a fleet of S92s and a few shagged out L2s and the next thing that happens to either brings us back to square one.

Some oil companies are already going S-92 (if they can get one) instead of 225 as soon as possible, business is too badly affected to wait around until February...June....or who knows when in 2013. Contractually, due to training and start up costs and amortization thereof, the change to S-92 will be long term.

Some helicopter companies are looking for used L2s (unaffected ones) but they are very rare. Some operators are asking EC whether or not they can produce new 332L1s with the carburized shaft...not sure what the answer is going to be.

[SASless]

HC....still think this is a minor hiccup?

[DOUBLE BOGEY]

SAS - if I gave you 10 minutes in an EC225 and you were able to see the incredible technology employed to enhance safety for both the PAX and the crew you would view this as we do - a stone cold tragedy!!

The only people who would consider a S92/AS332L1 instead of the EC225 are those that have yet to fly the EC225. Theres no point trying to contend this unless you have actually operated all three types/variants.

DB

[HeliComparator]

On the subject of learned limits, as I understand it (and could be wrong) the general idea is that because there is a (perhaps surprisingly) large variation in the vibration signature of the same element between different gearboxes, fault detection can be optimised by setting a limit specific to each gearbox. One could for example imagine looking at the LH side of the plots of the MOD45 and MOD70 shown in the AAIB report and working out the normal vibration level for that particular gearbox, then setting a limit which is some level and/or number of standard deviations above the normal limit. Thus the limit can be pretty close to the normal value without risking exceeding it unless there is a fault.

However this brings 2 problems, one is that the system has to learn the normal behaviour, typically I think over 25 hours. Then care has to be taken not to set too high a limit as a result of a defect in a gearbox element that was present from new. Thus there are also generic limts set, to ensure that the learned limit is not too high, and to give protection during the 25hrs learning process.

SAS, I would prefer it if you did not attribute comments to me that I never made. I realise that, despite living in UK for some time, you are American through and through and think that only American helicopters are any good. That national loyalty is commendable in some ways, but bearing in mind the degree of canineness of many products of USA such as your cars, those not subject to the national bias find it rather sad.

[Colibri49]

"canineness", that's a new one. For a moment I read it as canniness, but that wouldn't have been applicable at all.

[DOUBLE BOGEY]

HC thanks for explaining that to us. It makes more sense to me now.

Speaking of american cars, I once rented a Cadillac Escalade. Even the pedals had electric motors on them to make them move closer to my feet. However, the first freeway exit I tried to negotiate at a mere 40 MPH damn near killed me as it had more body roll than Glaswegian pie-eater and the kind of suspension that you would normally find on a waterbed.

I am not sure that the english language has a word to describe the curious mix of luxury and convienience married to utter incompetence at its its implied prime function....to be a car!!

DB

[Colibri49]

"if I gave you 10 minutes in an EC225 and you were able to see the incredible technology employed to enhance safety for both the PAX and the crew you would view this as we do - a stone cold tragedy!!"

Never was a truer phrase written. Yes, luck has played a considerable part in all 3 of the EC225 ditchings, in that nobody got seriously hurt. Bad luck and misunderstanding resulted in fatalities off Newfoundland in the S92 crash.

There will never come a time when helicopters in offshore operations are as safe as taking a city bus to work, but Eurocopter has done their utmost to raise the bar in the safety game and the EC225 package is about as sophisticated in terms of safety as things are ever likely to be in offshore helicopter operations.

This problem with the main rotor shaft metallurgy is an unmitigated tragedy for not only Eurocopter, but also for an industry which is forced back on to older and less efficient technology. Time will show that these older types are no less prone to scary and often unpredictable events.

The S92 is due for a mauw upgrade, but I'm not sure that I would feel comfortable as a pilot or passenger in an airframe which is already unnecessarily heavy for the job and almost guaranteed to resume suffering cracks when pushed to work even harder.

I agree that the EC225 seems increasingly likely to go the way of the Chinook and many readers might be glad of that. Eventually EC will find a convincing cure, but the damage to confidence will have been too deep and too long. I concur that it will be "a stone cold tragedy!!"

[Bravo73]

Cyclic.

<snip>

But if you are actually involved in real aviation you may like to take a few moments to ponder the impression you have tried to paint to all who read this forum of your personal view of professional pilots. Your statement is digraceful!!

Please let me know what Company you run so I can note never to apply!!

DB

Priceless.

DB, have you ever considered that someone could own their own company whilst also being a very experienced ATPL(H) (amongst other licences)?

:hmm:

[John Eacott]

It seems the North Sea oil companies are planning for a shortage in helicopter capacity for quite a while. Hope their new transport arrangements don't become permanent :(

Just to show that there is nothing new (and to negate the naysayers who deride the ship transfer proposal) we had a Stena ferry operating to the Brent back in June 1978 when there was yet another hiatus over helicopters from the Shetlands.

A helideck on the aft deck provided for 212 landings and all the workers were flown to their platforms without incident as part of the daily shuttle service.

http://www.helicopterservice.com.au/photos/pprune/Stena%20212.jpg

[cyclic]

DB

Luckily, although you can only see one industry through the blinkers you are wearing, I don't employ pilots as I don't have anything to fly. If I do move into aviation, I will have to forgo the pleasure of your company but I reckon you are pretty safe before Cyclic Airways hits the street.

By the way, I am very much involved in "real" aviation (whatever non-real aviation is I don't know) and I have taken a moment to ponder my words and found them not to be digraceful or even disgraceful - not all pilots are right all the time unless they are SAR pilots of course.

[DOUBLE BOGEY]

BRAVO 73 - I have considered many things. Thankfully your last post is not one of them!!

Cyclic - if your last post is the true account of your situation- why on earth would you make the statements in your penultimate post??

[Variable Load]

The only people who would consider a S92/AS332L1 instead of the EC225 are those that have yet to fly the EC225.

DB: Sorry, but I know quite a few that have flown both the S92 and 225 - consequently I know your statement is a gross oversimplification. Experience tells me it is more related to which of the two types the individual flew first!

How many commercial hours do you have in an S92 ;)

[riff_raff]

.....ANYWAY, back on topic, so far we have a few interim reports that DO seem to raise more questions than answers. There is an obvious reliance on HUMS which in my mind is simply a tool that we must use, and the chemists are looking at the materials used.......bigglesbutler- Just one last comment about the change in material for the EC225 spiral bevel gear shaft (and then I'll go away for a while). The AAIB special bulletin S7/2012 actually gave fairly detailed information about the shaft material/heat treatment. The shaft material was changed from 16NCD13 VAC-ARC (AMS 6263) to 32CDV13 VAR (AMS 6481). Regarding weldability, the only difference is that 16NCD13 has a lower carbon content than 32CDV13, 0.15% vs. 0.32%. While both alloys should produce sound welds using EB or laser, the 0.32% carbon content of 32CDV13 is getting close to the limit of what is generally considered weldable using a fusion welding process. Steel alloys that have a carbon content of around 0.40% or more can be prone to cracking when fusion welded, unless the parts are very carefully pre-heated before welding and post-heated after welding.

I'm sure EC has some very competent engineers working for them, and I'm sure they spent lots of time and effort developing this part design and manufacturing process. From what I have seen in the published reports, the basic design seems sound. And it's most likely there is a quality control issue on the manufacturing side of things.

For some perspective, here is a report describing a somewhat similar fracture issue with an EB welded gear shaft: http://products.asminternational.org/fach/data/fullDisplay.do?database=faco&record=409&search=

Lastly, in the spirit of disclosure, while I would not consider myself an "expert" in aircraft drivetrain engineering, I have spent the better part of two decades designing aircraft mechanical systems, including a couple of gearboxes. While I have no intimate knowledge of the EC225 MGB design and I have never worked for EC, I am quite familiar with the technical issues involved because I have had to deal with these same issues many times myself in my job. I hope no one has misinterpreted what I posted in this thread. I never intended to place blame, nor did I claim to have indisputable proof of what caused the problem. My only intent was to provide some technical perspective, based on my personal experiences, of the many possible factors that may have contributed to the problem.

Best regards to you all. I hope this problem is resolved quickly and satisfactorily for all parties involved.

riff_raff

[TalkSpike]

The only "stone cold tragedy" in this situation will be if the 225 starts flying again prior to:

1. The cause of the problem being identified;
2. A well thought out engineering solution being implemented; and,
3. The fix thoroughly tested and certified by relevant authorities.

Anything short of this will leave doubt in people’s minds and undermine the confidence passengers have in the aircraft.

If the 225 never flies again (I'm sure it will just using an extreme example to make my point) because an adequate solution is not found then far from a tragedy, this will be a huge win for offshore aviation safety.

[Pittsextra]

So in the name of not creating attention or to be critical of a major manufactuer then we should bury heads and pretend all is well in the world?

It isn't speculation when one asks questions around published data and I think the only impressive skills on display is an ability to read whats there. Quite why thats childish, desperate to prove anything or pretending to know more I have no idea.

There is no need to explain how to read my missives but this forum does tend to decend quite quickly into a squabble, now i'm suddenly a banker WTF?! What because some Sherlock Holmes has waded through my past posts to see I live in NW3? No I'm not a banker, nor have I ever been a banker - I'm actually retired.

Rather than trying to discredit me how about returning to the thread and the EC225, where I see the mud slingers don't seem to have much constructive points to add, beyond we should trust Eurocopter because it is a very big company employing a lot of people with
impressive degrees from good universities... Old age pilot I think Lehman Brothers could have claimed the same.

[DOUBLE BOGEY]

VARIABLE LOAD - To answer your question I have no commercial hours in the S92 so I have to concede to the point you make and my statement was based on the experience of others, but I undertsand the point you are making. The S92 is a fine ship and has many benefits to the Offshore Industry non the least of which is a great cabin.

My perspective on the 2 types is taken only in so far as I believe that the EC225 is leading the market at the moment with the safety innovations and the integration of avionics/flight display/AFCS to provide comprehensive flight envelope protection. I also believe that Sikorsky/AW will in time leapfrog the EC225 and produce something better from this perspective. It is just that at this moment, the EC225 leads the way.

At the risk of being fragged from all directions - it is also the case that there are a considerable number of people flying the EC255 that do not fully comprehend what it is actually capable of. This is a function of poor EC communication and a failure at certain cases for the correct information to migrate through the training process. This needs to be fixed not only for the EC225 but for any future helicopter with similar sophistication.

If, for instance, you do not fully comprehend the flight envelope protections built into the AFCS, it may cause the crew to de-couple right at the very moment that they need the AFCS the most. I am comfortable we have already seen this happen resulting in a highly undesirable result.

Unfortunatley, crews that are not fully aware of the complete capabilities of the AFCS and its integration with the other aircraft systems may inadvertantly make poor comparisons with other types, mistakenly believing that the EC225 sit in the same class....from a safety innovation perspective.

[SASless]

HC....nice try of deflecting the question.


I realise that, despite living in UK for some time, you are American through and through and think that only American helicopters are any good

I am clearly on the record singing the praises of the Alouette III, Lama, BO-105, BK-117, and the Wessex.....granted the Wessex is of American origin but the others are all Non-US origin.

Again....you seek to go personal when you cannot defend your earlier position.


Like about post 53 in this thread....or thereabouts on page two....I think.

If you bear in mind that the design of shaft has run for millions of flight hours in the 332L, L2 and 225 without problem (up until last year), then the concept must be OK. Some detail changed in the manufacturing process recently (different surface treatments etc) and that precipitated the problem for the Bond ditching. (Whether or not for this one, we don't yet know.). So I would say that since a small detail change caused the problem - albeit a pretty catastrophic problem - it is a small detail change to fix it.

I repeat my last question:




HC....still think this is a minor hiccup?

[HeliComparator]

SAS - so where did I say "minor hiccup"? I said the consequence of the problem was "pretty catastrophic" - not exactly a "minor hiccup" even bearing in mind the difficulty Americans have with English.

I can see that I shall have to explain the point I was making without using any long words, which as I have said several times before and since, is that the issue causing the fault is probably (we don't know yet) one minor change in manufacturing or operation of the shaft - one component out of the whole aircraft - and therefore probably a fairly straightforward to fix.

That said, since I made that post some time has passed and it is disappointing to see that little progress seems to have been made to determine the exact cause of the problem. Even if the fix is fairly straightforward, until the exact cause is known we can't progress towards it.

[DOUBLE BOGEY]

SAS - have you ever flown an EC225???

Your last post has slightly vexed me as I am morally and professionally inclined to support the incredible EC225 and do not like it when naughty boys trash it. Could I please ask you SAS, to be a little nicer about the EC225 so I do not feel like my head is going to explode when I read your next post!!!

Thanking you most kindly for your coinsideration of my Humble request.

It really is a nice helicopter, honest!!!

DB

Edited to be "nicer" to SAS after Albatross posted his plea for us to be more "Professional"

DB

[Pittsextra]

SAS - cut the crap - have you ever flown an EC225???

If not shut up cos you do not know what you are talking about.

If you have, what exactly do you think is the safety advantage of the S92 over the EC225 (setting aside the current airworthiness issue) - which of course the S92 has had its fair share of??

Come on lets here some real facts instead of supposition!!

DB

Are you joking? setting aside the huge issue which is what we are debating here.

What are the "real facts" DB

[albatross]

Hey Guys - Let's all play nice!
We are supposed to be professionals not a kindergarden playground with no teachers looking.
In the end no one will win and we'll look like idiots.
The thread seems to be going downhill faster than a greased crowbar and doesn't reflect well on us or the industry.
We all, I trust, want to see the 225 safely back in the air and the 92 to remain there also.

[Tango123]

Well said, alba

Targa, do you have anything to back the rumour up with? April is pretty far from now....

BR Tango

[DOUBLE BOGEY]

ALBATROSS - I agree and well said. I have taken a cold shower and given myself a damned good thrashing then changed my reply to SAS to reflect more "professionally" how I feel about his posts. Thank you ALBATROSS for making me a better person!!

TARGA - I can confirm that there is no truth in that rumour. The situation remains as it was and is posted on the EC website. Testing continues but as yet the root cause of the shaft failures is not identfied.

The root cause of the EMLUB false failure warning has been identified and a fix is being determined.

DB

[Pablo332]

Riff Raff
Any thoughts on the seemingly random start/finish points between individual shafts of the weld in relation to the 2 large holes in the lower part of the shaft?

[albatross]

Quote from DB
"ALBATROSS - I agree and well said. I have taken a cold shower and given myself a damned good thrashing then changed my reply to SAS to reflect more "professionally" how I feel about his posts. Thank you ALBATROSS for making me a better person!!"

"Your last post has slightly vexed me as I am morally and professionally inclined to support the incredible EC225 and do not like it when naughty boys trash it. Could I please ask you SAS, to be a little nicer about the EC225 so I do not feel like my head is going to explode when I read your next post!!!

Thanking you most kindly for your coinsideration of my Humble request.

It really is a nice helicopter, honest!!!"

Great Stuff DB - best laugh I've had all day!:ok:
Cheers Albatross.

[Lonewolf_50]

The root cause of the EMLUB false failure warning has been identified and a fix is being determined.

Do you understand that this fix (as it allows a bit longer flying before one must put the bird down if things go wrong with the shaft) is the one that may allow the lifting of the restriction, or is the shaft fix the show stopper in terms of when operators will have the restriction lifted?

Very nice to see that a feature that should help the crew out won't be (hopefully?) making their jobs more difficult.

[Colibri49]

"I'm not sure that I would feel comfortable as a pilot or passenger in an airframe which is already unnecessarily heavy for the job and almost guaranteed to resume suffering cracks when pushed to work even harder."

I'm quoting myself here and alluding to the S92. But though I love the EC225 dearly, I must be realistic and confess that until the MGB shaft crack issue is convincingly resolved, I would rather fly the S92 which currently seems more reliable. The 332L would also do for me.

What I don't want to happen is that the EC225 returns to service with the emlube properly functional, the HUMS tweaked to monitor the shaft unerringly, but flights to be conducted at reduced cruising power and short intervals between HUMS downloads because EC hasn't come up with a clear answer and solution to the metallurgy problem.

That would be a "fudge" in my mind and I would not be willing to lie to questions raised by any passengers, by stating that I'm completely happy and comfortable with such a solution.

Given that any believable modification to the manufacturing of the shaft could take years (at 2-ish shafts being produced per month) before all defective shafts could be replaced, I presently can't see how I'll be flying the EC225 for at least another year.

Love may be blind, but I'm too old to let infatuation obscure common sense.

riff-raff. You rock ! Please keep educating us.

[HeliComparator]

Lonewolf, I would say that fixing the Emerg lube will not change things, it is the shaft that is the show stopper. 30 mins sounds good but is only 40 miles, and at the moment it has not yet been established whether the gbx is airworthy for 30 mins at Vy with the bottom bearing no longer supporting the shaft.

[albatross]

A very good point HC.

[Pittsextra]

I think in the final analysis there will be a vibration/frequency that is destroying this shaft - which is not going to be an easy thing to fix because it will either mean changing the frequency or the affect of the current one on the affected shaft (usually by adding material so the natural frequency is changed). The problem is that it needs quite a bit of testing because not only do you need to validate you have fixed the issue but you may find the problem will just move to something else.

Even if that proves not to be the case and the shaft is failing for another reason questions should be asked around the initial assumptions prior to bringing the EC225 to market, the level of initial testing and the change controls around introduction into service different versions of FADEC software. Perhaps they were many and well documented, although in such a situation it is then not that difficult to revert to the previous versions that worked.

Regardless, there are a lot of red flags here and actually I don't think the shaft is the major one long term. The issue in my mind is that there doesn't seem to be a great deal of transparency around what exactly this EC225 is and there is a trend toward moving to rely on HUMS.

That would be fine if the data captured was well shared and the initial assumptions made around collected data from Eurocopter were well understood. However it is surprising to find Eurocopter revise down the thresholds by such a degree, which you wouldn’t expect with a history of valid data to cross reference against which it understood. It would also be interesting to come to a conclusion around exactly what drives the “learned” values and if they contain user definable parameters. I’m not sure simply assuming a failure is (for example) a 6 sigma event and sticking the threshold there is really good enough.

From the AAIB published data there is little point having Amber or Red thresholds because once the vibrations start to trend beyond the usual mean values they never recover. In fact worse the trends continue to a value that equals component failure in a timeframe that is so short (for practical purposes) you are unable to continue without servicing the affected part.

I would suggest that the initial thoughts around the workings of the HUMS system are that EC imagined an Amber alert would be a point of discussion with the operator about the ability to continue flying, whilst a Red alert was a"no go". From the data presented you have around 4 hours from thef irst Amber trigger until component failure. Which was even apparent from the May accident and yet I’d question the advice/decisions made with regard to the continued operations given the data available, even at that time.

If there is more background and information available then I do not believe it has been made available publically or even to stakeholders in this. Beyond the HUMS data Eurocopter have given persistent public direction to the 250K hours statistic (including to the helicopter safety group which they themselves are now reflecting) which is terrible because not only is it irrelevant, it becomes deception when there is specific relevant information around the shaft that is failing (i.e. the no shaft having more than 4000 flight hours statistic).


There is a lot of interesting debate around this incident and it would be disappointing to have that stifled. I take the point around vested interests but for people to even suggest that they would rather stay quiet because it affects their pay is quite incredible.


Edited to add - it would be interesting to see how the military operators of the EC725 are affected by these events.

[Colibri49]

Pitts

"I take the point around vested interests but for people to even suggest that they would rather stay quiet because it affects their pay is quite incredible."

I take exception to your uninformed statement and I'm reluctant to enter into any exchanges with you due to your generally unfortunate way of presenting your points, but I'll deign to pass you a fact of which you are probably unaware.

Nobody has implied that their pilot jobs and pay are under threat because the EC225 is effectively grounded. Not only are managers in at least two of the heli operators assuring pilots that redundancies aren't being contemplated, but also they are actively recruiting pilots in their dozens as we speak. In the case of one operator, flying training scholarships are being offered.

I don't like the "cut of your jib" Sir. As so often in life, it isn't necessarily so much what is being stated, but how it is presented. Try making your submissions in non-confrontational tones such as used by riff-raff, if you want to be more welcome.

[DOUBLE BOGEY]

Colibri - Well said Sir!!

[Pittsextra]

PITTS - The point is many of us here do have a VESTED INTEREST. To some of us it is our livelihoods, to others it is their method of transport to and from work. To the rest of you it amounts to rubbernecking and speculation. There is none so dangerous as he who has nothing to lose.

Post #640 above relates from an EC225 simulator instructor.

You seem to have taken one sentence of mine out of context.

[Old Age Pilot]

I don't like the "cut of your jib" Sir. As so often in life, it isn't necessarily so much what is being stated, but how it is presented. Try making your submissions in non-confrontational tones such as used by riff-raff, if you want to be more welcome.

:ok:

Well said Sir, indeed!

[HeliComparator]

Pitts, you PMd me and I have replied, but to save time I think I will paste my response to your PM below, since it covers some points you raised in your post:

I think you pehaps have a slightly false impression about what HUMS is all about. Firstly, it is not a primary means of assuring airworthiness. You can buy an EC225 that meets all the CS29 certification requirements, that doesn't have HUMS. HUMS is added as an extra layer of safety above and beyond that required for certification.

Secondly HUMS is by no means an exact black and white science, so since this shaft failure was the first time such a failure happened, it is not too surprising that HUMS thresholds etc are revised in light of "real" failure data.

On the point about the time to failure and the relevance of amber thresholds, what you say is correct for this particular component and failure mode. However there are plenty of other things that have a much slower failure progression rate where HUMS gives many 10s of hours warning.

Part of the reason for amber warnings is that false alarms continue to be an issue with any HUMS system. The sensors are all mounted externally to the transmission in the fairly "unfriendly" environment of heat, dirt, oil and airframe vibration. A common failure mode is that the sensor, or its connector or cabling, are not well attached (ie coming a bit loose) and so the amber threshold allows an attempt to rectify the alert by fixing the sensors, before having to take more serious action such as replacing the main gearbox. It is more appropriate for some parameters than others, for example the enhanced impulsiveness indicators (what used be called M6*) are better correlated to shaft rotation speed, so noise from a loose connection at airframe vibration frequency will have less effect than on say a bearing health indicator which just tends to work on rms and peak vibration level over a relatively wide frequency range, not correlated to the shaft rotation. There are something over 100 different parameters in a HUMS system.

So when you say the manufacturer could do better, I am sure that is true but EC is no worse in this area than any other manufacturer.

In summary, if HUMS was a tool for primary airworthiness I might be worried, but since it is just an optional extra layer over and above the basic certification, I am not worried. I flew helicopters for 10+ years before HUMS was ever invented!

[Pablo332]

Just for info
Those pilots who were operating out of ABZ how often and during which months did you notice the reduction in NR as a result of the -6000ft 14hz mod?
What’s the typical start up to lift off time at ABZ?
On approach/departure from/ to a rig how much time is spent below 60 Kts.

[DOUBLE BOGEY]

PITTS My reference to our livelihoods does not mean that any of us would fail to speak up to protect our incomes. This is about making sure we are safe and therefore our passengers are safe. No more, no less.

It upsets us when people like you, with limited understanding and knowledge, critise the system/process/manufacturer/us and in doing so create a poor impression of the system/process/manufacturer/us to our customers/passengers.

I am not sure why you feel so motivated to be interested in such detail.

[Pittsextra]

DB - I've got no interest in the back and forth fighting, after all i know nothing, although that might come back and bite in a few months from now.

You asked before why I was interested and I was told by someone else not to explain it. Rock and a hard place.

HC - thanks for the HUMS summary - I appreciate the failure was new and so absolute values for a failure might now be available for all sensors - although I wondered how the learned thresholds are devised given the spread between REDW and CNCN. Then how that fed into the decision making vis download times, thresholds in the period May to October.

[Pablo332]

MARMS was once described as the greatest advancement in helicopter safety since the introduction of the second engine. And I believe that it is. However it is still relatively in its infancy. Learned thresholds are required to compensate for the fact that all components are not created equal. Minor variations during manufacture may result in difference of vibration exhibited by the component. This is taken into account during the learning process, ie whats unusual for this particular assembly.
It’s unfortunate in the current scenario that MARM can only detect a crack that is in its final stages before failure. It won’t detect the start of a crack.

[DOUBLE BOGEY]

DB - I've got no interest in the back and forth fighting, after all i know nothing, although that might come back and bite in a few months from now.

See PITTS, there you go again!!!???

[DOUBLE BOGEY]

"MARMS was once described as the greatest advancement in helicopter safety since the introduction of the second engine"




OOOH Pablo - you are probably going to get all the SEH freaks squeaking about that second engine, especially SAS who probably flew in "Nam" with no engines at all, in a snowstorm, in the dead man's curve and never died once!!

DB

[Pittsextra]

DB if everyone at Eurocopter is as arrogant as you it isn't hard to see this mess has come about....

[Pablo332]

While I appreciate adding a second engine adds to the probability of having an engine failure by 50%. What’s your experience of operating the 225when it’s a bit cold.

[Pablo332]

Wasn't quite sure 100% on the 50% bit but 100% may be laying it on a bit thick. Thread now diverges to accommodate statisticians. Any info out there on the NR info?

Edit this response was to a post that has disappeared?

[bigglesbutler]

Those pilots who were operating out of ABZ how often and during which months did you notice the reduction in NR as a result of the -6000ft 14hz mod?


Once or twice its come close but I have yet to taxi with anything noticably less than 100%

What’s the typical start up to lift off time at ABZ?

Assuming no traffic and pax are ready about 10-15 mins.

On approach/departure from/ to a rig how much time is spent below 60 Kts.

last mile perhaps not taking into account wind or poor vis/night approaches.

Pitts, I concur with Colibri, it isn't WHAT your asking its how you are asking. You have slated people and companies, do you honestly expect no reaction?

Si

[Pablo332]

During what months did you come close?

[bigglesbutler]

During what months did you come close?

NO IDEA, when I don't consciously make a note of something I can barely remember what I did yesterday never mind what might or might not have happened months ago :ooh:

Feel free to go onto the met office website and look at the temperatures and pressures for the past year, then compare that to the NR laws for the EC225 then you will know when/if it went below 100%.

Si

[Pablo332]

Thanks for the info. If I could push you for a little more information do you conduct OEI training in a simulator or on a live helicopter

[HeliComparator]

We used to do all our OEI training in the aircraft, between 2005 and 2008. By the end of 2008 the Helisim 225 sim became available and each pilot made 1 visit per year, the other 6 monthly check including OEI was done in the aircraft. In the last couple of years nearly all training been done in the Sim. Only Sim To Aircraft adaptation for new pilots is done in the aircraft.

So the amount of OEI training decreased a lot over the past 2 years, compared to before.

On the subject of Nr / density altitude, the Nr is rarely below 100% with the APM engaged. Of course, after start and until APM is engaged, it can be down to as low as 98%. Offshore is usually warmer than onshore in the type of weather conditions giving very low density altitude, so I doubt the Nr is ever less than 100% offshore. With the latest software, Nr is more often up at 103.8% compared to the previous version, but versions before that were more like the current one, so it is difficult to see that as the issue. Only Nr <100% is new.

[Pablo332]

Heli Comparator
Thank you for the information. From what you say would it be fair to assume that most 225s on the north sea seldom have a reduction in NR due to density altitude issues?

[SASless]

DB.....actually 99.9999 percent of my Vietnam flying was with two engines....there were some occasions it was with one....and yes there was one occasion where it was with none.

No snow and ice in Vietnam but well yes....there were lots of hours spent in the "Dead Man's Curve".....and I did think I had died several times but fortunately had not despite some golden opportunities.

For Snow and Ice....I did the Arctic....for the Dead Man's Curve I did lots of forestry and construction work.

So what is your point besides talking like a Prick?

[HeliComparator]

No, that's not quite what I said. I meant that Nr is rarely below 100%. It is more routinely below the nominal 103.8% at low airspeed. For example at the moment the density altitude is about -1100' which gives an Nr slightly reduced to 103%. But the pressure is quite low at the moment. With a high pressure winter scenario, say 1030 HPa which is not unusual in mid-winter, temperatures below 9degC results in Nr below 103.8% in hover / on ground. With 1030 HPa and -4 degC, Nr would be starting to go below 100% but because Aberdeen is near the sea, it doesn't often get that cold.

[Pittsextra]

Pitts, I concur with Colibri, it isn't WHAT your asking its how you are asking. You have slated people and companies, do you honestly expect no reaction?

What does that even mean?? If you don't disagree with what I say why make a fuss or an objection? This whole situation is very grim and while you ask the question "do you honestly expect no reaction" I'll reflect the same:-

2 helicopters have ended in the North sea and a lot of people have been affected as a result, and currently neither the CAA or EASA agree on how safe this type is. Do YOU honestly expect no reaction?

[HeliHenri]

From Flightglobal :

Bertling: EC225 grounding 'biggest issue' in Eurocopter history (http://www.flightglobal.com/news/articles/bertling-ec225-grounding-biggest-issue-in-eurocopter-history-379866/)

"Eurocopter faces the "biggest issue" in its 20-year history, according to its chief executive, as the airframer attempts to deal with the fallout from two related ditchings of EC225s in the North Sea.
Speaking at a Helicopter Safety Steering Group (HSSG) meeting in November, according to minutes seen by Flightglobal, Eurocopter boss Lutz Bertling admitted the UK's oil and gas industry had "lost confidence in the EC225 helicopters and in Eurocopter".
Although the EC225 fleet used for offshore transportation in the oil and gas sector has been grounded in the UK and Norway since October, after rulings by both countries' civil aviation regulators, Bertling says Eurocopter's first priority is not to return the Super Pumas to service, but to "regain confidence in the aircraft, company and solution".
Eurocopter is still attempting to identify the root cause of the cracks in the main gearbox bevel gear shafts that forced the ditchings of helicopters operated by Bond Offshore Helicopters and CHC Scotia in May and October respectively.
Eurocopter chief technical officer Jean-Brice Dumont told the HSSG meeting the company believes the fractures were caused by "resonance" and it has embarked on a flight- and ground-test campaign to verify its hypothesis. Although speculation has focused on the potential need to replace hundreds of the gearbox shafts, Dumont says if its theory is correct, "the fix will lie in the internal operating conditions as opposed to the part itself".
However, helicopter operators and oil and gas companies may need further convincing before regaining their trust in the company. Speaking at the meeting, Richard Mintern, Bond Aviation Group chief executive, said industry should form part of the validation process.
Bertling supported this suggestion and, in addition, offered industry representatives the opportunity to visit Eurocopter's Marignane plant to see "details of the investigation, testing, general design and maintenance processes".
The minutes also highlight a disagreement between European regulator EASA and the UK's CAA on how to proceed following the second ditching. Giles Porter, representing the UK regulator, says it requested that EASA include operational limitations in its airworthiness directive, issued on 25 October, "however, they were resistant". Therefore, the CAA went ahead with its effective grounding notice.
To lift the overwater flight ban, Porter says: "CAA airworthiness experts must be satisfied that all problems have been fully resolved so that there will be no recurrence of the incident."
.

[Camper Van Basten]

If it could be proved beyond any doubt that a software upgrade or 14Hz mod was responsible for a harmonic / vibration change within the MGB, which subsequently led to the shaft failing, and that upgrade / mod could be reversed, would you as Pilots and Engineers be happy to operate the 225 once again?

Just putting it out there, because from an EC point of view that would surely be the easiest fix.

[SASless]

Is this an impossible standard?

"CAA airworthiness experts must be satisfied that all problems have been fully resolved so that there will be no recurrence of the incident."

[industry insider]

Terminus mos first mentioned the 14hz and FADEC V12 on 18 November in post 453...So, EC have suspected this as the potential problem since at least mid November.

There were some Fadec changes and EC is currently examining the effect of Version 12 Fadec software which was released in response to the 14 Hz vibration to slightly lower the Nr.

So, nearly one month later, if EC goes back to V11 or even V10 FADEC software, fixes the EM Lub indications, temporarily reduces the torque, speed and TOW, and specifies 3 hour HUMS downloads, who will be the first to re instate the EC225 into service in those countries where it is not grounded and would the UK CAA accept those measures to unground the EC225?

[DOUBLE BOGEY]

SAS - Sorry mate I made a bit of a Joke at your expense but it was a joke. I should not have mocked your Military Experience so please accept my apology. I am ex Army Aviation but I am one of the lucky ones that never saw any action so big respect for your Service and please accept my apology. It was really just a joke.

Best Regards

DB

[DOUBLE BOGEY]

PITS - you are missing the point again. EASA is not responsible for Commercial Helicopter Operations Regulations - yet. It is responsible for airwoirthiness issues. It has not grounded the aircraft because, under certain operating restrictions, it is safe to fly.

UK CAA regulate Commercial Air Transportation Operations in the UK. Operators must comply with JAR-OPS 3. They have placed a restriction on operations over hostile territory (Open water areas North and South of 45 dgrees fall into this category).

EASA and CAA are in agreeemnt, they just have different legal and regulatory responsibilities and what we are suject to is the manifestation of those responsibilities.

On top of all of that the Manufacturers under Part 145, The Oil Companys under there own expositions and the Operators under the AOC approvals are also legally oblidged to conduct their own internal risk assessments and make judgements that may or may not be in line with the Regulator. However, in this case, I beleive all stakeholders are in exact agreement. We cannot tolerate hostile environment operations without the required level of safety. That is the big challenge at the moment.

I hope this makes sense.

DB

[HeliComparator]

Camper, I would say yes, because we did around 70,000 hours prior to this software version without a problem. However we did a moderate amount of flying with this software without a problem, so the issue is to be convinced that it was definitely the software change that caused the problem and not something else.

[JohnDixson]

The Flight Global posting containing a reference to a main gear box resonance reminded me that in early 1963, the CH-47A prototypes at the Test Board ( Ft Rucker ) experienced either two or three incidences of catastrophic nose gear box failure. Resulting shrapnel went into that engine intake and all in all created lots of noise and a mess, not to mention the adverse notoriety associated with the precautionary landings, one of which was on the golf course ( the old one ) adjacent to the Officers Club. Boeing determined rather quickly that the box had a resonance and the corrective action was to raise the Nr from 204 to 230. Problem solved.

After joining SA and learning the numerous factors affecting the design and qualification elements in the drive train, I was always amazed that Boeing could raise the power-on Nr that much without incurring other major problems.

Although one might at first think that the overall engine response at 14 hz is an unlikely trigger, one would assume that EC would be doing ( have already done? ) extensive frequency domain testing in the qualification process for the control system change. That sort of testing ( I refer to in-flight testing ) sometimes uncovers unexpected results.

[SASless]

In the CH-47C....the Nr changed again for higher MAUW's. Along the way from the A Model....the Engines changed considerably as well. The Early C Models had a very serious flaw in the Power Turbines....that caused catastrophic failures and in almost all cases the loss of the aircraft when shrapnel severed the fuel lines and started massive fires.

She had her problems....but is still the best helicopter I have ever flown. Sadly, I did not get the chance to compare the big Sikorsky aircraft and think the 53E must be a treat to fly.

[HeliComparator]

Hi John

Just for clarity, the 14Hz thing is nothing directly to do with this issue. There was a possible flight control instability at 14Hz at very low density altitude - air too thick! As you know, once the loop gain of a control system exceeds unity, any disturbance will result in divergent oscillation. Thicker air = more control power = more loop gain.

In the case of the 225 this could occur with density altitude somewhere below -2000'. In order to get around the problem, the loop gain had to be reduced and this was done by reducing the Nr at low density altitude. So at normal to high density altitude, hover Nr is 103.8%. But this reduces down towards 100% as density altitude decreases. The latest version, which allows flight in density altitude down to -6000', has the Nr going as low as 98%. So operation with Nr below 100% is a relatively new thing, and there seems to be a theory that this could be the problem.

[Lonewolf_50]

John D:

Your post reminded me of all of the deswirl ducts that fell off of Seahawks (TFOA - arrrrgh!!!). IIRC, that clamp failure got traced to either NSV or ASV that originated in the T-700. (HMU? One of the pumps?) Been a few years, I can't remember the fix.

I do remember that on preflight we used to have some detailed looks at the deswirl duct clamp to make sure it hadn't cocked or loosened. The word on the street and in various tech bulletins was that you could detect an impending clamp failure by inspection between sorties. If it wasn't "sitting right" you'd have maintenance either replace it or confirm its soundness before launch.

As one cannot check stuff inside the gear box in pre flight ... the operator's means of mitigating (if the root cause of this is in the vibration domain) for the 225 is of course more difficult.

[Pablo332]

Does anyone know if the shafts of the aircraft currently on the ground at ABZ have been NDT eddy current checked?

[JohnDixson]

Thanks for your note, HC. I surmised from your previous posts that they were doing something smart like that.

My personal experience with flight control excitation into the various airframe modes was that once you get beyond say 7 hz, the output rolls off significantly, mostly due to the actuators of course*. But my experience also says " never say never ", so if the gearbox shaft issue is one of resonance, it will be interesting to see how it arises.

* But the outcome can be " attention-getting ", and things can get sticky near instantaneously, thus we typically installed a cockpit " kill-switch".

You appear to have good contacts with the troops at EC, and one of the aspects that arrested my attention ( and I may have the story screwed up, so this query may be a non-starter ) is the basis for the continued flying after the first incident. On the one hand, it seemed to be perhaps novel, but then justifiable, use of the HUMS accelerometers to provide a go-no-go decision. On the other side of that procedure, I was wondering just what sort of specimen testing had been done, if any, on the lower section of the shaft. The normal questions: how many specimens, stress levels high enough to generate failure or were they low and all specimens were run-outs etc. Where I am coming from is that assigning a three hour safe life carries a message that one has a very firm handle on the fatigue strength of that piece, and on the repercussions of a failure. Then, after the second occurrence, it seemed as though there were reconsiderations as to the integrity of the remaining drive, following a shaft failure.

It's well to remember that EC will want to investigate, test and substantiate a solution, which they will then present to the authorities, on their own. OEM's learn early on not to get the qualification authorities involved in the redesign/solution process.

I'd be surprised if , by now, they are not certain of the cause, are juggling the implications of alternative solutions, and testing same. Some of the estimates that have been posted regarding get well schedules seem unreasonably pessimistic, realizing that at EC, this is Job One. It would make for a very interesting AHS paper.

[HeliComparator]

Hi John

One of the new features of the 225 vs the L2 is the response rate of the main servos, bandwidth was over 16Hz. This is quite noticeable if, for example, you knock the cyclic by accident- the response is instant and dramatic! In response to the 14Hz problem they fitted modified servos that had reduced bandwidth, down to a little below 12Hz but of course the concept of bandwidth means that the response is only diminishing, not zero, above 12Hz. It is still sufficiently high at 14Hz to require the other solution ie reducing the Nr at low density altitude.

On the subject of the 3hrs, as I understand it the crack develops perhaps 20 hrs before failure, but is only detectable by HUMS within the last 4 -6 hrs or so when the shaft starts to lose rigidity. The crack progression can of course be determined by the beach marks as discussed in the AAIB bulletin. As far as i know the 3 hrs was practically tested only by the 2 events and so it does not seem to have huge integrity. This of course is one reason why the operators and oil companies decided not to fly crew change flights using this procedure, and CAA followed suite with the ban on public transport over hostile terrain. However if you are operating over landable terrain it is less of a big deal - if the worst happens, you just land and no big deal. So I think it is right that the procedure is there to support certain types of operation - just not N Sea crew change!

Edited to add-just re-read your question and I see I misinterpreted it - you are asking about the procedure after the first event. Again I think it was only based on the observed propagation rate of the event. Not very robust, but presumably adequate to persuade EASA to allow it.

I don't think anyone actually used it - in Bristow we had none of the relatively few shafts affected (those with the new-profile hole) and we waited to take delivery of our new EC225s until they had re-worked shafts without the cavity.

[JohnDixson]

Should have been more precise, HC. Sorry. SA, for the non-fly-by-wire controls typically ratchets down the hydraulic feed to the AFCS actuators to 1500 psi or less, and they are the reason for decreased response above about 7 hz ( and of course the typical filtering around the basic aircraft modes ). Do the Eurocopter machines get 14 hz out of their Autopilot actuators? In any case, it would be interesting if any of those inputs make that MR shaft "ring".

[HeliComparator]

Hi John

Maybe we are slightly at cross-purposes here. I am talking about the main hydraulic servo controls in the head. These run at 175bar (~2600 psi) and the instability arises from having the transmission (on which the servos are mounted) flexibly attached to the airframe, whilst the pilot's flight controls are rigidly attached to the airframe.

The 225 has two different types of AFCS actuators in series for each channel (for redundancy) - hydraulic servos in the Autopilot Hydraulics - I think very similar in concept to those fitted to the S61 - running at about half the pressure of the main servos, plus electric SEMAs which are digitally controlled fast electric screw jacks with built-in positioning feedback loops. I am not sure what the bandwidth of these is, but I suppose there is not much point in having main servos that are significantly faster than the AFCS series actuators.

The 225 autopilot is extremely precise but smooth. I think the digital control loops are not a digital replication of an analogue control loop as they were in the 332L2. But even so, it smacks of a high gain control loop to me which, unless bandwidth is high and hence phase shift is low, would result in instability. However there is no hint of instability in the 225's control loops and this may be in part due to the high bandwidth of the various control components thus minimal phase shift.

Waffling a bit there, but the relevant point is that I don't think the problem is any hint of the 14Hz oscillation, rather it is the steps taken to avoid the oscillation that might be having unintended consequences.

[JohnDixson]

HC, I think your description is what I had envisioned, up to the difference in servo mounting, which I knew at one time but completely forgot until you mentioned it. Thanks for clearing it up. All of these considerations will be history soon, as the industry transitions to FBW and all of the mechanical mixing, boost actuators, Autopilot/AFCS actuators and related claptrap vanish. I think I can hear the Maintenance and the Safety Community saying a loud " Adios ".

[HeliComparator]

Eeek - I have got used to no rods/ cables / bits of string between me and the engines, not sure I am ready for same between me and the swash plate! Is there currently a civil certification standard for FBW in helicopters?

[riff_raff]

Riff Raff- Any thoughts on the seemingly random start/finish points between individual shafts of the weld in relation to the 2 large holes in the lower part of the shaft?Pablo332-

Sorry for the tardy response, but I only browse this thread once every couple of days.

As for the two larger, diametrically opposed holes in the conical section of the shaft below the weld joint, I could not say for certain what their purpose is. The only thing I could speculate is that they are windows to allow the spray from a lube jet to deposit some oil onto the inner wall of the spinning bevel gear shaft. The oil deposited on the inner shaft wall would work its way up to the spline connecting the bevel shaft to the sun gear of the first epicyclic stage.

If you look at the nice cross section drawing someone posted a while back, you'll note that there is also an o-ring seal just above the spline and a carefully located vent hole thru the sun gear wall just inboard/below the seal. The purpose for this arrangement is so that the spline joint operates submerged in lube oil, and that the oil flowing from one end of the spline to the other flushes out any microscopic metallic debris generated by rubbing between the spline teeth. This arrangement is common practice with highly loaded spline joints in aircraft gearboxes, and it is done to minimize fretting wear in the spline tooth flanks.

Sorry for the long winded explanation. Hope you found it useful.
riff_raff

[Pablo332]

riff_raf
Thanks for that explanation of the 2 large holes, when I think back I do remember an oil jet adjacent to them.
My main query was with the start/finish point of the weld. On some shaft pictures it’s directly above one of the holes, on others it’s not. From a stress strain point of view would it not be better to have this point directly above one of the large holes or exactly 90 degrees to it?

[helicrazi]

Anyone know what happened with the CHC L2 yesterday? The papers are making a meal out of it as always!

[JohnDixson]

HC, not that I am aware of. Maybe I'm just out of touch. FAA has to get on the board soon, if one takes all of the 609 media statements as credible.

[cjbiz]

http://www.youtube.com/watch?v=oD4jKBOIBwc


A good bit of PR from EC, will it be enough? Here's hoping it's a start!

[HeliComparator]

The shape of the offending shaft looks surprisingly squat / broad, hard to see it as a weak point -but it obviously is.

[Clive J]

Air Accidents Investigation: Download PDF document (http://www.aaib.gov.uk/cms_resources/Annual%20Safety%20Report%202012.pdf)

AAIB Annual Safety Report

Quite a few entries including a section relevant to this thread.

Regards, Clive

[212man]

Bevel Gear Manufacturing Process

I liked the pronouncing of nit-riding!

[Pittsextra]

AAIB Annual Safety Report

Quite a few entries including a section relevant to this thread.

Regards, Clive

It does indeed, and one might wonder how the 2013 report might reflect things.

Particular highlights are recommendation 2011-033, 034, 036, 042 and how HUMS data is being used in 043

Not only that but it also highlights the inter relationship between the AAIB, CAA, EASA and Eurocopter. Some of these outcomes are surprising.

[Ant T]

Slightly off-topic, but relevant to what has been happening -

My step-son is a captain for a shipping company that operates various types of workboat. He was recently at a Dutch shipyard taking delivery of a new fast crew-change vessel of a type they use for shifting crews working on construction of offshore windfarms (~ 14 passengers @ 22kts) . He was told that the shipyard had been asked to submit design proposals for a larger crew change vessel that could carry 60 passengers at 30 kts, potentially for oil-rig crew change work.
This seems to support the suggestions here that this long-term unavailability of the 225 is causing people to look at alternatives, but on the other hand, he thinks from his experience that there would be an awful lot of the time that it would be out of limits for the transfer onto the rigs (I think he said their limits on the wind-farm work for transferring on and off the vessel was about 1.5 metres swell).

[Fareastdriver]

Wind farms are closer to the shore and in more benign conditions than an oil platform.

[industry insider]

There is little doubt that this EC225 issue is going to cause some structural changes in the industry.

I know of several oil and gas companies located offshore where the sea is calmer than the NS who are considering new fast crew boats capable of seating 80 and having lie flat beds. Companies who make crew boats are ramping up their marketing to the oil and gas industry.

[TipCap]

We had crew change boats of Bahregan in Iran in 69/71 but they still needed helicopters.

I don't think the NS should be too concerned

TC

[AnFI]

... this thread is a sorry indicator of the damage caused to the fundamental concept of the helicopter which we all love so much. Boats instead of helicopters? Terrible news.

Over-complex and under performing machines in terms of 'safe passenger mile bang'/buck reduce the ancestral right of the helicopter to be the obvious transport mechanism of the future. It would be sad to see helicopters regulate themselves out of practical use.

Too many engines and too many gears and bearings in gearboxes (16 gears in a 225 GBox? how many ball bearings?) (Four gearboxes!?) makes unreliable and eye-wateringly expensive helicopters.

The simplistic economic falsehood that you sell more engines if you require twins is obviously flawed; an example is the sales ratio of single squirrels to twins - many more engines sold in singles than twins (by a factor of about 20:1) - the economics for helicopters is better when sound engineering philosophy is applied.

The maths used to support the 2 engined theory is IMHO flawed in many ways (for example: squaring 1/100,000 to compute chance of double engined failure, the wrongly assumed independence of engines etc ). EASA said there was not enough evidence yet to show the simplex concept could be used yet - it is surely the other way around - this idea to carry a spare engine is a safety concept where the maths is bogus and the incidence rate does not accord to the theory.

AND anyway since ditching is not that uncommon then avoiding it at the expense of carrying payload crippling two engines is questionable - especially if the payload employed were used to make arriving in water even safer and more inconsequential. The maths of the twin is dependent on the consequences of arrival on forced landing being high probability of fatality. Since there are so many other reasons to forced land then payload should be 'spent' making that super-safe. You could even make an 'Auto-ditch button' if you don't trust the pilots to do it?

Sacrificing the weight/expense that could be spent making critical components more robust (AW139 tail boom and rotors) and carrying more fuel and other practical safety features to carry excessively over-engined machines might be illogical (as Nick Lappos quite rightly used to try and point out)

Maybe we're too far gone already?

OTT rant over, I know the routine; coat, door etc

[SASless]

The Gulf of Mexico has more than a few helicopters....and Crew Boats.....and it is a fairly benign bit of water most of the time.

There is a place for each mode of transport....neither can replace the other.

[AnFI]

"There is a place for each mode of transport..." - perfectly true

[Fareastdriver]

a fairly benign bit of water

You can operate crew boats until the time comes to evacuate owing to an impending hurricane, cyclone or typhoon.
Then your boats are too slow to shuttle the required numbers.

[industry insider]

You can operate crew boats until the time comes to evacuate owing to an impending hurricane, cyclone or typhoon.
Then your boats are too slow to shuttle the required numbers.

Not necessarily FED, there is a new breed of fast (45 knot) crew boats which seat 80 in business class style being marketed to the oil and gas industry right now. Of course, one cannot do 45 knots in rough seas but where some companies operate, the sea is calm much of the year.

Studies are ongoing to replace at least some helicopters with fast crew boats. The initial analysis shows commercially 3 fast crew boats for each helicopter is possible. Transit time each way would realistically be 8 hours.

[Fareastdriver]

It does not matter how fast or how comfortable the boats are. When the conditions are outside the boat transfer limits you cannot use them. Offshore workers are not sailors; getting to/from a boat by a fixed object in anything other than a flat calm is fraught with danger unless you know what you are doing; and that covers the North Sea most of the time.
The bean counters will look at it, obviously, until people are stuck either on or offshore. They're not worried, they have a nice warm office.

Edited to add. Have you seen a 'fast 45 knot ferry' bouncing aound in moderate seas? You can get away with hydrofoils to a certain extent but they are only designed to float on the main hull at docksides so they are going to swing all over the place at an offshore installation.

[throw a dyce]

I lived in Hong Kong for 3 years and used ferries daily.The 250 seat mono hull DB ferry could be quite bouncy in windy conditions,where the 500 seat twin hulls were very stable.The Macau hydro foil was fantastic most of the time,but one crashed into debris and sank.
However the sticking point was in typhoon conditions they all stopped sailing,and that was in a harbour environment.The North Sea is way rougher,but the HK GFS helis continued flying in those conditions.

[SASless]

Having lived offshore on a Semi-submersible Rig that was used as a hotel....anchored next to a Platform....I know what it is like to approach a Rolling Ladder when the Rig is heaving.

It is an interesting experience to say the least.

Being Craned up from a Workboat is also a thrill....and has its own dangers.

No....boats are not going to put helicopters out of business.....particularly on the North Sea. The Sea is too rough too often....and the distances are too long. Making transit times too long which means "manpower costs" that have to be factored into the equation.

[industry insider]

I am not talking about the NS though. There are some very clever people studying this issue, including the whole transfer processes at each end. The 225 needs to fly again soon.

[jimf671]

I am thinking that the regulators' 45 degree latitude limit is highly relevant.

[lowfat]

Do you think the bears will take 2 days out of their days off transiting to a rig by boat?

Even if it had gogo dancers I can't see it.

The 225 is dead long live the S92!

[SASless]

Maybe Columbia might show up with some Chinooks....and really confuse the mix! Perhaps all the hundreds of thousands of hours the old girls have flown since leaving the North Sea might be enough for the Bears to give then a second look. That assumes those operating them continue operating them to the standard they are. Logging is a helluva lot harder on the machines than trundling out to the rigs and back.

[cyclic]

Yep, I'm up for the Chinooks - proper noise complaints from Mr Trump! Those wind turbines will seem like a minor inconvenience to the Great Dunes of Scotland.

[Fareastdriver]

All the research on ways and means of getting on and off these high speed ferries will take years. The marine fraternity see an opputunity for boat travel leading to their benevolent market. During those years the problems with the 225 will be fixed and the previous status quo will prevail. By the time they have got their boats sorted out all of last years troubles will have been forgotton so there will be no need for them.

I doubt that more the 30% of today's offshore workers have heard of the Chinook.

[AnFI]

If it's too rough for boats then how are forced landings with floated helicopters and transfers to dinghies supposed to work?

[lowfat]

They use this

Operation of the Dacon Rescue Scoop - YouTube

[bondu]

Notice that the 'body' at the beginning is wearing a yellow survival suit, which becomes an orange suit for the close up. The dummy, with floppy arms is in the yellow suit; the guinea pig is in the orange suit, so he can tuck his arms in so they don't get caught in the net.
And no way were the waves 4m!

bondu:ugh:

[jimf671]

All the advantages of a Sproule net.


... get my coat shall I?

[Tynecastle]

The crew boats were tried several times by a company out in S E Asia some years ago, and were not a success, even in the relative calm waters a lot guys were not able to work for a day or two due to sea sickness, and if they were in a key position, that meant their back to back had to cover for them.
No doubt one or two were milking it, but it caused a big problem for the Rigs
One positive thing that came out of it was that the offshore guys did not complain about the Helicopters for a month or two after they tried the boats.