Special bulletin now released:

Air Accidents Investigation: S2/2012 EC225 LP Super Puma, G-REDW

Well done that crew!

That'll be what's meant by multiple indications! Good work getting it down from 3000'. :ooh:

Out of interest, what does the 'SHOT' caption indicate?

Well done to the crew :ok:

BBC reporting that the oil pressure loss was caused by a crack internally on the rotor shaft. No idea of the 225's oil flow routing so cannot expand.

It's French for 'FU@@ED'.

More onthe story here.

BBC News - Bond Super Puma ditching caused by gearbox crack

WELL DONE
 

Would all the naysayers now like to join in wishing hearty congratulations to the crew of G-REDW for successfully completing a textbook ditching, resulting in the safe recovery of all passengers and crew and leading to the recovery of their aircraft so the AAIB can get accurate information as to the cause. :ok:

Thanks to HeliComparator for his early insightful and reasoned posts which were spot on.

A very well done to the crew and to their management for being supportive during the usual Sky News and BBC reports looking for someone to blame and coming out with all the "what-ifs" and other disaster scenarios :mad:

Well done !
 

Yepp, Very well done :)

So with the report stating that it was a crack in the gearbox that caused the MGB pumps to fail, are the other operators going to ground their aircraft to check for this problem or are they going to continue flying? I haven't seen anything with Bond written on it leave the airport today, so have they grounded all types?

You can always check all three companies schedules online and see if they are flying. What it doesn't say is which type/variant they are flying with. I would hope that all the operators have read the initial report and are formulating a plan.

I'm sure HC will come up with some ideas as to why the SHOT indication was also showing.

Sky is reporting that Bond have suspended flying on both the EC225 and also the L2. CHC and Bristows are apparently still flying as normal.

I have no insight knowledge but my gut feeling says it might be worth loosing one or two days of flying until an official EASA / Eurocopter announcement has been made just to be on the safe side. Not pleasant for people stuck offshore but it would certainly bring some peace of mind to passengers and crews alike.

would the AAIB not issue a warning to inspect,ground until further notice after the inspection showed cracks?
Or would that come from Eurocopter direct?

It isn't "cracks", it is one 360 degree crack around a shaft. The AAIB has no authority to ground aircraft, it can only give advice to the authority.

At the risk of starting an old War all over again....does the 225 have a MGB design problem? I know all about the zillion hours X 10 to the ump power....and how the Laws of Probability work.....we have had that discussion too. But notwithstanding all that....is it Bond or the 225 that has the problem? Is the fix a simple Exorcism at the Bond Hangar or something bigger at play?

I am making no suggestions....just asking a question.

If it was a 92 involved....I know exactly where this discussion would be right about now.....and am just wondering why not with the 225?

I accept the 225 was seen as superior because of the Emergency Lube system but now we see that can also be done in by events. Added to the other problem identified with the MGB design....is the 225 as safe as once assumed?

SAS

I think Eurocopter will need to come up with answers and quickly. Until that time there are going to be numerous theories and I would love to get into them now but because of how the press works over here, I am keeping my ideas offline. The exorcism does sound like the best one so far though!

cracks or crack the failing of the drive to both pumps suggests the separation of the shaft. perhaps not enough for any form of gap as such but is the component up to task or as SASless suggests, does the 225 have a problem?
The outcome is what matters for sure. Well done to the crew :D

I think the main reason for so much of the discussion and argument around the S92 was the lack of clarity as to what the aircraft was or wasn't capable of doing with no MGB lubrication, not the lack of a backup lubrication system. There is no doubt as to what to do in this case with 332/225 range.

P1

Bond ditching
 

Excellent work, the answer for the loss of px in the Mg/b has been found. Let us hope this is the answer to the catastrophic failure as well, put some minds at rest. Interesting that Bond have suspended all 225 and L2 flights ( BBC report ). Great action by them, will this happen across the board I wonder? I guess a mandatory grounding will be imminent anyway.

We were told offshore some time ago that HUMS was a wonderful addition to helicopter safety. With this in mind, would someone care to comment on these words from the Interim Report:

These sensors had recorded increasing vibration
levels during the previous few flying hours prior to the
accident flight and were being monitored, in accordance
with the manufacturer’s maintenance manual.

It has raised questions out here on Safety Meeting Sunday - it would be good to give the troops some more feedback.

Can someone explain how this internal crack led to an external oil leak, as reported in yesterday's media?

Driving both oil pumps from the same shaft - the main and stand-by - evidently enables a single failure to cause complete loss of oil pressure.

Am I being old fashioned by suggesting that any stand-by system should be totally seperate from the main system, and any failure (short of a catastrophic xmsn disintegration) that causes the main to fail shouldn't affect the stand-by?

"SHOT" is simply the wording on the Emergency Lube activation button on the overhead panel. It illuminates (I think, if someone has access to the FM and can correct me please do!) when 2 conditions are made: ac is in flight and the MGBP caption is activated, which was the case here.

Vibrations change on helicopters all the time. I don't know if similar systems are installed offshore, but I'm sure if one of them showed a similar change the immediate action would not be "quick, shut it all down, take it all apart and check it" but "interesting, we'll keep an eye on that". The procedures for doing so are well laid out in the aircraft maintenance documents, and in this case it was being done "in accordance with the manufacturer’s maintenance manual."

This is an interesting last line from the report:

"Detailed examination.......of the reason for the indication of a failure in the emergency lubrication system continues."

Not "failure of the emergency lubrication system" but "indication of failure in the emergency lubrication system"? Maybe I read too much into it but are the AAIB currently thinking that the Emblube system was in fact working, but the indications were that it was not, leading the crew to "land immediately".

Obviously no criticism of the crew here, the Emergency checklist is unequivocal in this case and ditching was the only and correct course of action, which they did perfectly.

Cyclic.....I will grant 24 hours grace before reminding some folks of past statements perhaps....as this latest event is certainly going to cause (or should at any rate) some serious reconsideration of the relative merits proclaimed so loudly and at length in the past.

I wonder if other operators are having similar problems with Main Gear Boxes?

Bond appears to have grounded their fleet.....why would they do that and other Operators not do the same.....what do the other Operators know that Bond doesn't? Are the Bond Aircraft unique? Are the other Operators carrying out special inspections and/or reviews of HUMs data (or both)? Has there been any AD action by Eurocopter or any of the Administrators? Any industry wide notifications yet?

Bond easily could be the tragic victim of Fate but one does have to wonder if there is some organic cause similar in nature to the Norwegian S-61 Spindle failures many years back. That had to do with an operational technique that was unique to them. Is there something similar going on here?

Not suggesting there is but merely raising one of many questions that begs asking. i would think the AAIB will take that as one of the many lines of questioning they will apply to this and other events re the 225/L2 MGB design.

Helicopters suspended as gearbox fault blamed for SuperPuma ditching | News | Aberdeen | STV

Seems almost certainly a manufacturing defect of the shaft (AAIB says crack in the vicinity of a weld joining 2 halves of the shaft). I see EC now has a bulletin on TIPI indicating that there is a batch of suspect shafts - I believe a recent batch. Fortunately we don't have any of that batch on our fleet so we are not affected.

PCD - yes I noticed the wording as well, and of course they said some glycol was found in the MGB. There are 2 pressure switches, one for the bleed air and 1 for the glycol. After pressing the SHOT button, the system waits 20 secs and then expects both pressure switches to be showing pressure. If not, MGB EMLUBE illuminates and it is Land Immediately.

Trouble is those pressure switches are only activated with a real emergency or during maintenance, the rest of the time they do nothing except sit there and degrade. When we first got our fleet, the maintenance interval was 750 hrs and we routinely found 1 or other switches inop. We reduced the check to 375 hrs and I think we change them at 375 hrs(?). I am not sure whether this is our company procedure, or whether it is now manufacturer's procedure. In any case, chances are that the EMLUBE was working but they had indications of failure. In that respect it is a poorly designed system.

We just fleet checked the pressure switches and all ours were found to be working correctly.

This would explain oil leakage - with the engine bleed air pressurising the gearbox, oil is forced out of every orifice and low pressure seal making a right mess. (it has happened, though fortunately only on the ground!)

HC

Coatimundi

HUMS is a fantastic safety tool but not perfect. One problem is that there is so much data, that a "top level" reporting system is needed to interface between all the data and the engineers. This reporting system uses various thresholds and triggers - anything below the trigger / threshold is not presented "in the face" of the engineer, but can be viewed by delving into the raw data.

The thresholds have to be set somehow, and in the early days of HUMS it was mostly guesswork. Various events and experience with false alarms etc have allowed the thresholds to be refined over the years. But since there has not been a previous failure of this shaft, there was no information to allow refinement of the appropriate thresholds. Now there is, so hopefully another small improvement to HUMS will result.

For the time being, the operators now know to keep a close eye on this parameter pending refinement of the thresholds.

HC

HC -my thanks for the clarification on those points. As a former pilot I have been asked to speak with my colleagues on my offshore installation this evening, and your input is much appreciated.

True, but the risk of that shaft detaching from the upper part of the main gearbox drive shaft (which is a single point of failure anyway) may have been analysed as being lower than that of any alternative design.

(There’s a gearbox diagram on the G‑REDL accident thread here.)

What happen's now..??
 

With the AAIB initial findings does that mean the helicopter will be released back to Bond..??

Will she fly again..?:)

I would be surprised if it comes back into service. I think the damage and cost of repair would make it a write off.
I also noticed that the BBC tv news today mentioned the controlled ditching (they may have said landing) however the newsreader felt the need to offer his own comment and call it "a crash landing to the rest of us". Irritating buffoon.

Extremely Remote ?

The following is from "AAIB Bulletin No: 8/2004" referring to the L2 G-JSAR incident, 22 February 2003. Though the actual failures are different, I find the similarities in the monitoring scenarios somewhat concerning.

jimf

I think it would be mistake to read into these texts that operators are not bothering too much about HUMS alerts. The nature of the HUMS beast is that it is uses external accelerometers to monitor and extract vibration signatures for individual shafts, gears and bearings within the tranmission (ie it is non-invasive) all in a pretty nasty environment of heat, dirt, salt, oil and grime not to mention overall flight vibration (not to be confused with transmisison vibration).

The net result is a relatively high false alarm rate, or at least a need to be circumspect in not jumping in with both feet when the HUMS squeaks, without thinking carefully about it.

The false alarm rate is much lower these days - as I mentioned earlier, HUMS is an evolving science (or maybe an art!). It is not perfect, but I get nervous when it is implied that "it don't work so it ain't worth having" because whilst far from perfect, it is still a quantum step forward in flight safety.

In our company we have a couple of very experienced engineers whose sole job is to keep tabs on the HUMS systems, even though these are supposed to be "user friendly" to line engineers, and we do take any such trends very seriously, but at the end of the day a qualitative judgement has to be made as to whether it is a significant issue or not. 99% of the time we get this right, and it doesn't make the papers. Just occasionally it goes wrong and then does make the papers!

I take your point HC.

Thanks to everyone for their comments on this - much appreciated by the offshore workforce :ok:

^ ^ ^ ^
What he said. :ok:

Just as a postscript to the HUMS issue, apparently the user can adjust the thresholds at which alerts are generated and we have now significantly reduced the thresholds for the oil pump drive parameters as of this morning.

In our company, we have always downloaded and analysed the HUMS when we return to base, even when it is a rotors-running turnround (as it often is). On the 332L2 this is not possible since there is no method of forcing a termination of the HUMS session onto the card whilst rotors running. The ability to rotors-run download is something we insisted on before taking delivery of the first 225 (and I recall we had to pay EC extra to develop it!). However the manufacturer's procedures do not require HUMS to be dowloaded like this - their view is that once every 25hrs is adequate. I am not sure whether other operators routinely download on every arrival at base - it would be interesting to hear if they do?

In my view the manufacturer should be more proactive in encouraging operators to make the most of HUMS. For the time being, they regard HUMS as an "optional extra" (although of course it is a regulatory requirement for N Sea) and I think it is time this view changed!

With the small amount of information regarding a 360Deg crack near to or in the vacinity of a production weld joining two parts together , could indicate a production problem related to inncorrect stress relief/ normalising after heat induction caused by welding, unless carried out almost like a scientific test normalising will cause either embrittlement or loss of tensile strength.

But for so many Helis to have the same fault would need all of them to have been fitted with the same sort of faulty shaft/bevel gear from the same possibly faulty batch of shafts, which almost seems to be impossible..!

Does anyone know if this affects the Military Pumas?

Peter R-B
Lancashire

I'd be interested to see the evidence upon which you are basing this claim.

Certainly none of Bristow nor CHC aircraft in Abz have these suspect batch of shafts, not sure if Bond do but there are only 9 affected shafts in existence worldwide (and not all those necessarily installed in an aircraft). The shaft design is a different part number than installed on the 332 and 330, though I believe retrofit is possible at least on the 332. All the shafts are visually very similar, the ones fitted on the 225 have modified treatments as the primary difference.

Just as I thought; thanks HC. Are you picking-up the slack, so-to-speak? I only ask as I'm scheduled to be inbound from the Northern-most reaches tomorrow.

HC- I have been out of the HUMS arena for a few years now (Formerly Systems Engineer on IHUMS) back then (Early part of the Noughties) we had pretty good control and interpretation of the systems data output, however even in mature airframes, we had the odd failure which was on something we hadn't actually been monitoring directly.. anyway, my question..

The CAA funded a study (carried out by Smiths) to develop a "neural networked" HUMS system which would be smart enough to evolve its own thresholds levels. What was the outcome? I was recently at an HM Gov Tech Strat Board competition launch where they invited bids for funding to develop HUMS systems, although after I questioned the TSB staff it turns out that they felt it was a good subject matter, although they had no idea that in fact it was already a mature system as they had not carried out any research.. :rolleyes: Nor had they had any contact with CAA SRG on the subject :ugh:

So are you guys still plodding on with the systems we had ten years ago, or has there been significant technology advances in terms of data collection, processing and interpretation? Is SMART HUMS any nearer reality? I mean real advances here.. not just a sexy new name or a swish new display format on the PC's. I look at advances in data processing and application engineering in areas such as communications and entertainment and can't help but think HUMS should have evolved at the same rate by virtue of the same architecture?

Interested in yours and others opinion on the matter.. :ok:

We will do our best to keep our customers happy and pick up some slack, but there is certainly not sufficient spare capacity to replace all Bond's flights so I am afraid some disruption to you guys is inevitable.