EC225 crash near Bergen, Norway April 2016

[Helicopterfixerman]

Mitchaa,

The only thing I would say about your reasoning is that you are assuming that if the head was installed on 27th March, it hadn't been disturbed since. We don't know the full maintenance history for the aircraft. It surely is possible and plausible that the system had been disturbed between 27th March and the fateful day.

The ASB issued by Airbus covered only the suspension bar attachment and fittings:

Check for correct installation of the suspension bar assembly:
- correct fitting of the lower and upper pins
- presence and correct position and condition of the locking pins
- check the tightening torque of each of the attachment bolts of the MGB bar fittings as per MMA 53-26-00-212 and correct any discrepancy according to the task. Measure the values in accordance with Figure 2.

It was the EASA AD that introduced MGB filter chip and HUMS checks.

Once again, I'm not suggesting that suspension bar failure or error is the cause, but it's possible. Just because it hasn't happened before...........

[john6016]

A three leg chair & suspension rods, 100% speculation but willing to be educated.

I’m not sure the EC225 suspension rods are best represented by the three leg chair / Jesus nut theory. Several points to think about:

I assume they are normally subject to a stretch force but it you look at the diagram in post 42, at an angle of around 45 degrees they should also provide a degree of longitudinal support, via the rotor bearing / casing (although I can’t find what type of bearing this is). I’d guess the rods can act to stretch and compression forces as that is what they look to be designed for (it is a rod).

Now the Rotor shaft, this seems to be supported against gyroscopic / asymmetrical lift forces by the main rotor shaft, gearbox bearings, & rotor bearing. The three leg chair does not fit this situation. I can imagine the loss of one support rod would place an additional load on the bearings that may lead to eventual failure, but not an instantaneous failure.

[Carrera4]

In post 493 (picture) you can see the rh coupling flenge is bendt upward. This is a steel tube that work as a rear engine mount with the high speed shaft innside. I belive that if the forward suspension bar breaks this tube will be bendt downward since the MGB will tilt backward.

[rans6andrew]

I don't want to open another can of worms but, if, for any reason, the mast and head moves with respect to the rest of the airframe the control systems WILL cause the blades to fly in un-commanded ways. Either the swashplate follows the mast and the rods that position it will cause unwanted control inputs or the swashplate stays aligned with the airframe and the links to the blades will move them in unwanted ways. I suspect that a small amount of mast relative movement could put enough control input to the blades/head to cause it to be ripped out of the airframe. This might explain the rocking motion seen by the observer before the head departed.

The same might happen if the control system gave a sudden un-commanded input if, say, something else let go that impacted or disrupted it.

[dipperm0]

Popular proverb : There Are None So Blind As Those Who Will Not See

G.REDL fuselage end of suspension bar : bented, twisted
LN.OJF fuselage end of suspension bar : looks undamaged

[roundwego]

I am amazed no one has latched onto the barbecue plate. You are all so preoccupied with support rods you are not considering 101 other causes.

Let's face it, none of us have a clue what happened and are just wasting time speculating. Let's just leave it up to the experts who have (nearly) all the evidence in front of them and will produce some answers as soon as they can.

[skadi]

It was the EASA AD that introduced MGB filter chip and HUMS checks.

These points were added in Rev1 of the Airbus EASB

skadi

[Skotty]

There seems to be some confusion about the loads taken by the suspension bars and by the main gearbox attachment to the airframe structure.

The suspension bars carry the vertical loads. The lift force is transmitted through them to the structure and so they are under tension. In the hangar the weight of the head and gearbox is transmitted through the struts and so they are under compression.

The gearbox is attached to the structure via the barbeque plate which is designed to take up the horizontal forces and not the vertical loads. It picks up the main rotor reaction torque and the longitudinal and transverse loads while damping the vibrations. The fact that it is not designed to transmit vertical forces is obvious from its design. For an example of a main gearbox attachment that is designed to transmit the lift forces look at Sikorsky.

During flight the aircraft is actually hanging from the suspension bars.

[birmingham]

Despite more than 4 million hours of safe flight and that a rational explanation of the cause is in progress it would seem that the passengers and the E&P companies have already decided that this is one catastrophic mechanical failure too many. CHC is in poor financial help, Airbus has a PR and sales nightmare.

The outcome of the investigation is necessary for the victims families to understand what happened, for manufacturers and operators to learn lessons but whatever the conclusion the Superpuma's days as the North Sea workhorse are surely over.

If companies wont rent it and passengers wont ride in it it is a legacy helicopter

[terminus mos]

Birmingham


it would seem that the passengers and the E&P companies have already decided that this is one catastrophic mechanical failure too many. CHC is in poor financial help, Airbus has a PR and sales nightmare.

You are welcome to your opinion but if this is down to a failure mode which is simple to fix like the strut mounting bolts being checked by the latest EASB, the 225 could fly again. As for CHC having financial problems, Chapter 11 could be just what CHC needs to stop bleeding cash to the leasing companies who won't negotiate. As for Airbus, well they can spin their way out of most things.

As an oil and gas company advisor, I have spent many hours this week in front of my CEO and Directors. Not one member of our board has a closed mind to re habilitating the 225. We have all flown in the 225 and as a company, we have many safe hours of 225 flight.

If and when appropriate, we will design and follow a process with our stakeholders and passengers, regardless of the time and complexity of such a process. We are not at all desperate, we run a mixed fleet and activity levels are such that we can make do with the other aircraft we have contracted for a while.

[Colibri49]

CHC Files for Chapter 11 Bankruptcy Protection - Oil Industry News - Oil and Gas News (http://www.oilandgaspeople.com/news/highlights/8408/chc-files-for-bankruptcy/)

[letmein]

john6016
I can imagine the loss of one support rod would place an additional load on the bearings that may lead to eventual failure, but not an instantaneous failure.

Would this be possible:
1. Holding pin of suspension bar pops out in flight (possibly due to improper install)
2. This allows transmission to move a little in the vertical axis
3. This causes engine input shaft bearings to experience massive side loads, leads to failure of bearings.
4. Engine input shaft start to wobble causing inter-meshing of gears
5. Transmission produces metal causing failure of epicyclic
6. The rest same as L2 (REDL)

[Satcomm]

Birmingham - never say never! Let's just replace 60% of the helicopters in the North Sea. What do you suggest we replace them with? Guess it would be great if we could replace it with something that is guaranteed not to fail. Even with the guarantee, the cost and down time implementation of this would be astronomically. The retraining(hopefully) of everyone from drivers, maintenance, ramp staff to passenger and management would be astonishing. Now minus the guarantee of a perfect aircraft, because that does not exist, I think the safety factor would drastically decrease with drivers that have limited experience of type, engineers that are fixing aircraft they are as familiar with and even ramp staff doing daily operations around aircraft they are not use to. The downtime and limit aircraft support while waiting for aircraft to be manufactured and staff ramped up would have oil companies crippled for passenger movements. The spin off to this would have massive consequences, from cost, fatigue, moral, etc.

[Self loading bear]

Letmein,
You beat me to it!
I just want to add the the shaft will probably also be subjected to tilting moments.

And the pin failure might be caused by missing or failing nappy pins?
Did we see a complete fork on the suspension bar or might there be one side missing?

SLB

[Lonewolf_50]

john6016


Would this be possible:
1. Holding pin of suspension bar pops out in flight (possibly due to improper install)
2. This allows transmission to move a little in the vertical axis
3. This causes engine input shaft bearings to experience massive side loads, leads to failure of bearings.
4. Engine input shaft start to wobble causing inter-meshing of gears
5. Transmission produces metal causing failure of epicyclic
6. The rest same as L2 (REDL)
How long do you think the sequence of events (2-5) takes in this scenario?

[Skotty]

If you have several tons of load suspended by three point of attachment and you remove one of those attachments the load is going to move more than a little!

[henra]

I’m not sure the EC225 suspension rods are best represented by the three leg chair / Jesus nut theory. Several points to think about:

No, a three legged chair is indeed not really representative for the suspension layout of the 225. At least not 1:1.

I took this very simplistic example to show that two out of three remaining suspension points do not simply equate 2/3 of the strength.

I can imagine the loss of one support rod would place an additional load on the bearings that may lead to eventual failure, but not an instantaneous failure.


That would happen if the remaining structure would be sufficient to keep everything in its place.
However, the suspension rods in the 225 are there to take the vertical load. I can't imagine the relatively fragile conical housing and joiners will be able to take the load from a missing front suspension. They are not designed for that. And in that case it would rip off the epicyclic module and/or conical housing and the whole Main Rotor would tilt rearwards with whatever remains of the structure underneath.

[birmingham]

Birmingham



You are welcome to your opinion but if this is down to a failure mode which is simple to fix like the strut mounting bolts being checked by the latest EASB, the 225 could fly again. As for CHC having financial problems, Chapter 11 could be just what CHC needs to stop bleeding cash to the leasing companies who won't negotiate. As for Airbus, well they can spin their way out of most things.

As an oil and gas company advisor, I have spent many hours this week in front of my CEO and Directors. Not one member of our board has a closed mind to re habilitating the 225. We have all flown in the 225 and as a company, we have many safe hours of 225 flight.

If and when appropriate, we will design and follow a process with our stakeholders and passengers, regardless of the time and complexity of such a process. We are not at all desperate, we run a mixed fleet and activity levels are such that we can make do with the other aircraft we have contracted for a while.

I have nothing against the thing personally and pointed out its 4 million plus hours record. I would certainly use one, but to suggest this time it is business as usual is naive in my view.

[victor papa]

The mgb stay lower attachment have nothing to do with MRH removal/installation. In fact unless you remove the mgb stays for a scheduled inspection they are often not even desturbed for mgb removal except for the upper pins.

The pins are a close tolerance fit safetyied by the nappy pins so that if they move they cant move beyond the safety pins. So no they wont just fall out especially seeing they carry vertical loads after 1 or 2 flights. However over time and the inevitable torque reaction off the strut it will work loose eventually. How long this will take is anybodies guess but it will be more than a few flights.

I can not remember the maintenance manual instructions on the 332 but on the 350, 120 you can fit the upper attachment bolts in their case anyway round but the lower must be in the direction indicated in the manual which funnily enough is in the torque opposing direction so if they come loose somehow they will work themselves towards the stay not away.

For those continuing to compare to REDL pls read the report and the full report on that tragic accident and do not miss the parts referring to chip warnings, HUMS thresholds adjusted, etc. It did not happen out of the blue! Is someone to blame? No but loads of human factors and system failures were identified and it did lead to increased awareness to follow OEM instructions and improve comms in writing with OEM's to prevent a reoccurance.

If we all could take the time to actually read the full reports on all 332/225 accidents and/or incidents and make sure we know where what is on the aircraft then maybe we could have more intelligent debates without emotion from all speculating and argueing for and against on here but please go read the actual reports and not the newspapers first.

[Lonewolf_50]

Please forgive my not being familiar with 225 slang/jargon, but what's the barbecue plate?


Transmission picture (http://www.pprune.org/rotorheads/578298-ec225-crash-near-bergen-norway-5.html#post9361013)

Install Bevel Gear Video (http://www.pprune.org/rotorheads/578298-ec225-crash-near-bergen-norway-5.html#post9361187)

Rotor/transmission/struts figure (http://www.pprune.org/rotorheads/578298-ec225-crash-near-bergen-norway-6.html#post9361269)


In these various pictures and the video of putting the bevel gear into the transmission, where do I find the barbecue plate? (Please don't tell me "in the lunch room, of course!" ) :)

[Skotty]

The gearbox sits on the barbeque plate to which it is bolted. It is slotted to absorb the horizontal forces from the head/gearbox and it is attached to the upper fuselage structure.

It was visible in one of the photos posted still attached to the gearbox, but I'm not sure where that photo is.

[HeliComparator]

Please forgive my not being familiar with 225 slang/jargon, but what's the barbecue plate?


Transmission picture (http://www.pprune.org/rotorheads/578298-ec225-crash-near-bergen-norway-5.html#post9361013)

Install Bevel Gear Video (http://www.pprune.org/rotorheads/578298-ec225-crash-near-bergen-norway-5.html#post9361187)

Rotor/transmission/struts figure (http://www.pprune.org/rotorheads/578298-ec225-crash-near-bergen-norway-6.html#post9361269)


In these various pictures and the video of putting the bevel gear into the transmission, where do I find the barbecue plate? (Please don't tell me "in the lunch room, of course!" ) :)
It's not in the pictures (didn't look at the video) but anyway it is a slotted plate that attaches the bottom of the gearbox to the transmission deck. Called the BBQ plate because of its slots. The slots are designed to give the plat some flexibility to allow the bottom of the gearbox to sway a little whilst constraining it in rotation (ie taking the torque).

[roundwego]

Please forgive my not being familiar with 225 slang/jargon, but what's the barbecue plate?


Transmission picture (http://www.pprune.org/rotorheads/578298-ec225-crash-near-bergen-norway-5.html#post9361013)

Install Bevel Gear Video (http://www.pprune.org/rotorheads/578298-ec225-crash-near-bergen-norway-5.html#post9361187)

Rotor/transmission/struts figure (http://www.pprune.org/rotorheads/578298-ec225-crash-near-bergen-norway-6.html#post9361269)


In these various pictures and the video of putting the bevel gear into the transmission, where do I find the barbecue plate? (Please don't tell me "in the lunch room, of course!" ) :)
The barbecue plate is the slang term for the gearbox "flexible mounting plate". It is the interface between the base of the gearbox and the airframe and it is designed to resist the rotational forces acting on the gearbox. It is made from titanium but, as its formal name suggests, it is flexible. It has been in use on the AS332 series and H225 for many years.

[albatross]

Years ago probably late 70s early 80s there was a tragic accident with a Puma in Canada caused by BBQ plate failure.
As I recall - BBQ plate failed while the AC was in the hover picking up a longline load.
Transmission torqued to the right which caused the #1 engine drive shaft to be torn loose.
#1 engine over sped and shut down ( this disabled overspeed protection on # 2 engine )
Transmission then torqued left which took out the #2 engine driveshaft. # 2 engine over sped and, due to disabled protection, exploded causing a large fire and crash.
BBQ plate was redesigned and cycle counts for multiple longline sling ops were imposed.
Just mentioned as I am sure the subject may come up.
I am not speculating that BBQ plate failure is a causal factor in this accident.

[Fareastdriver]

It has been in use on the AS332 series and H225 for many years.

and the 330 Puma from 1966; that's fifty years.

[Americanadian]

We suspect the front lower suspension bar pin's diaper pins were never installed.

[Pablo332]

The barbecue plate is the slang term for the gearbox "flexible mounting plate". It is the interface between the base of the gearbox and the airframe and it is designed to resist the rotational forces acting on the gearbox. It is made from titanium but, as its formal name suggests, it is flexible. It has been in use on the AS332 series and H225 for many years.
I think its made of Marvel on the 225.

[jimf671]

So who is deleting posts again?

On some fora you get half an hour to reflect on your sins and then it's there forever!

[dipperm0]

Just to clarify

[Lonewolf_50]

Many thanks to all for the explanation. :ok:

[Heliport]

So who is deleting posts again?



The people who posted them.

[Never Fretter]

Mitchaa has gone from 28 to 17 posts in total today by deleting all but 3 here (ones where he was proven wrong?) and others on the CHC thread.

[Rigga]

Skotty,
You're a brilliant ray of shining light amongst these 500+ posts of poop!

[ericferret]

Probably a good idea, if all the dross was deleted the thread would be a damn sight shorter.

I will delete this tomorrow!!!!!

I'm with Skotty. Having seen the end result of a 3 legged lifting sling breaking a single leg I can testify that it doesn't end well. Simple mechanics.

[donut king]

http://bt.mnocdn.no/incoming/article3590196.ece/ALTERNATES/w2048c169/IMG_6661.JPG?updated=030520161246

Flex plate still attached.....is it not? See left side of MGB bottom!

[henra]

When the main rotor head was installed on the 27th March, were there 3 pins installed in the suspension rods?
Do you believe that incorrect pins were installed? If so, why?


Honestly, I've got no idea. It is simply one theoretical cause amongst multiple. How it could have happened? No securing pins installed on the bolts? corrosion? Wrong bolt? Other ways I didn't come to think of?
If it was a problem with the suspension bar and how it could have come lose we will only know once the experts who have access to the data and wreckage have come to a conclusion. Until then its just possibilities and -yes- speculation.

[SASless]

CHC has filed for Chapter 11 Bankruptcy protection.....what is the next step in this Drama?

[TylerMonkey]

We suspect the front lower suspension bar pin's diaper pins were never installed.

Wow . . . . serious first post.

[Lonewolf_50]

@Tyler
Depending upon who "we" is in that sentence.

[Americanadian]

CHC bankruptcy was inevitable.

[cteneto139]

Sir, I think the legends are changed... just saying...

[Satcomm]

What happened to the Airbus, AIBN and CHC leading us to believe there was no human error/misinterpretations. I would think forgetting to install the diaper pins would be human error ... Just saying. I think "we" is just throwing something out there.

[VortexRinger]

I've heard the same from a number of different people now. Washer, nappy pins and possibly the round fire wall panel still in the hangar.

[VortexRinger]

This is only rumour and not fact yet.

[Arnie Madsen]

re: suspension strut pins .... whether loose , wrong size , or retaining clips missing I cannot see them falling out in flight ..... they are carrying +20,000 lbs and you could not drive them out with a sledge hammer.

On the ground with just enough lift to equal the MRG and rotor system (no weight on the pin) it could move a bit .... maybe that is what happened .... pin slid partway and only 2 of the 3 eyelets were carrying the load and bracket bent and distorted in flight .... just thinking out loud at possible scenarios.

[TowerDog]

. re: suspension strut pins .... whether loose , wrong size , or retaining clips missing I cannot see them falling out in flight ..... they are carrying +20,000 lbs and you could not drive them out with

Not so fast.
Constant vibration with loading and un-loading of the strut pin(s) could certainly move it sideways, slowly but surely.
I sure as hell would not bet my rotor or my life on a guess the pin would not move if not secured.

[jimf671]

This is only rumour and not fact yet.

Like 500 other things!


So the suggestion is that a pile of bits sat in a hangar for HOW LONG?

[EDML]

The front strut also carries dynamic loads. There might even be load changes from tension to compression on large fwd cyclic inputs.

[domperry]

Latest from AIBN, not that it adds too much:

"All the components from the helicopter are now moved to the AIBN's facilities in Lillestrøm. The helicopter parts were transported on two trailers, and arrived on Thursday morning. Here, the AIBN will continue its efforts to sort and analyze both components and other information. The participants in the investigation are currently working from their home bases, before the team gathers in Lillestrøm early next week to continue the work together.

The search for components at the accident site will resume tomorrow. The main focus for the search is for parts connected to the main gearbox. The search will continue as long as required."

Dom

[SimCaptain]

More or less the same info:

Norwegian newspaper, VG, reporting this afternoon that the AIBN is still looking for more parts from the gearbox. They say, they "have much of it, but still need more pieces".

Further on they say that "all the parts they've got is all important in this early stage of investigation. A gearbox like this contains many parts - and we are still missing several pieces".

[Satcomm]

May eat my words on this but not buying the missing diaper pin theory. Mainly due to the length of time between the accident and the MRH/MGB replacements. Having worked in the industry long enough, find it really hard to believe, at this time with all the safety nets, such a critical part would be missed. The first engineer would have to forget, the second engineer (initialing the independent) would either have to have gained enough trust in the first guy not to look, however, I cant imagine he wouldn't at least asked (which is when you would think the first guy would go "oh $#%&"). There would most likely be a checklist/greasy thumb copy of the major component replacement that gets attached to the work card where someone checked installing the pins (again "oh %$^*, I forgot the pins). Now this is just the 2 guys signing for the job, there would be several other engineers involved in replacing either of the above 2 components, possibly even a shift change (maybe not for MRH) where another set of guys would have been involved. After all that, hangar/stand cleanup, I think someone would have noted a firewall panel, washer and 2 diaper pins left over and questioned why.


So all that got missed, the aircraft has been flying for a month (according to the rumors) since the MRH replacement. There would have been a significant amount of daily inspections, preflights and turnarounds in which no engineer picked up of the missing panel. I realize its down in the bottom of the firewall behind the engine but I think it would be picked up on a daily. Engineers minds are trained to pick up on the anomalies not the thing that are correct. Again, after all that time, someone is now just noting the significance of the parts sitting in the hangar ... I don't know guys, really seems far fetched to me.


I guess nothing is impossible but its not like this is HS's first go at a puma. I do not work for HS but I do think they are a probably the most experienced super puma operators out there. CHC like all the other big boys, have all the known safety nets in place and is just hard to think such a small yet critical step creeped through the cracks for so long.


Obviously like everything else on here, this is just my own speculation and in due time we will hopefully find out the true cause so that the chances of it happening again are minimised.

[TylerMonkey]

Any unlocked pin that is a sliding fit (not a press fit) in a vibrating environment has a good chance of rotating even if it does this very slowly.
If that happens on a vertical pin ( up down ) it may/should stay in the hole by gravity. On a horizontal pin all bets are off. It can't move any farther in one direction but it sure can go the other way. Could take weeks.

[SASless]

We may assume they mean the crash site and not the maintenance hanger or store room I guess!



More or less the same info:

Norwegian newspaper, VG, reporting this afternoon that the AIBN is still looking for more parts from the gearbox. They say, they "have much of it, but still need more pieces".

Further on they say that "all the parts they've got is all important in this early stage of investigation. A gearbox like this contains many parts - and we are still missing several pieces".

[squib66]

So Shell's suspension stands and they are about to start flying with Bristow in Norway.
https://www.energyvoice.com/oilandgas/north-sea/108898/north-sea-helicopter-crash-shell-finds-alternative-flights-bristow/
Have they revealed anything about the Shell Aircraft review?

[Special 25]

Would it be fair to say that the aircraft was just at top of descent, about to make its final approach into the airfield. This is assuming that the crew had made any control input at all that might have precipitated the sudden break-up.

If so, the rotorhead and gearbox were being unloaded, not loaded. The former might lead to the final critical slipping of the strut retaining pin, rather than loading up the head which might lead to gearbox, strut mounting failure.

As I recall, the bottom of the strut feeds into a fork arrangement where the pin is threaded through two eyelets. Assuming (again huge assumptions) that there were no diaper pins and firewall plate, how far would the pin have to move to release the strut. Would coming out of one eyelet be enough to lose the structural strength of the pin?

[Rigga]

...they don't add Retention Pins to any design just to add to aesthetics.
They are designed to be there to prevent Pins moving...

[buzz66]

Can't be a Sus Bar failure because the Gearbox split in 2 parts.
Sus Bar or Pin failure would see the Barby Plate and whole gearbox leave the scene. Almost has to be major Gear failure internal to the Gbox.
I bet my bottom dollar they are the bits they want to still find.

[Apate]

So many 225 fan boys falling for the Airbus ploy of deflection.

Forget the AH and DGAC noise, they are simply covering their backsides and are totally untrustworthy. The stakes a very high and they are trying to save a product line here.

The truth will come out once it is known. It is NOT known at the moment IMHO.

[Scuffers]

Can't be a Sus Bar failure because the Gearbox split in 2 parts.
Sus Bar or Pin failure would see the Barby Plate and whole gearbox leave the scene. Almost has to be major Gear failure internal to the Gbox.

Not so sure about that, loose one of the three bars, the pull on the remaining two would put massive side/load onto the output shaft and I doubt the gearbox would stand that for many seconds.

[jimf671]

buzz66

Let's work the odds here for your bet. Forget the stuff about the split and the barby plate.

Has anything like this happened before? Yes.

Was it the bars or the epicyclic module that failed? Epicyclic module.

Eh? ...

[Never Fretter]

Apate says they are simply covering their backsides and are totally untrustworthy.

That's your anonymous opinion, but you know what they say opinions are like.

buzz66 says Can't be a Sus Bar failure because the Gearbox split in 2 parts.


I agree with scuffers: not necessarily. As the lift housing becomes under-supported the modular MGB could fail in a number of ways as it is exposed to loads outside its design case and potentially some secondary impacts.

Let's work the odds here for your bet.

Luckily the AIBN have to do better then saying it looks a bit like another accident.

[Sanus]

Jim,

I wouldn't take the wager.

Last Monday morning Airbus Helicopters distributed letter 3031-S-00 definitively stating that all operators can safely return their 225's to service (subject to local approval). They based their comments on "additional information gathered during the last 48 hours" i.e. Saturday / Sunday.

The implication is one of maintenance error. Soon after the release of this letter strong rumours were leaked about the discovery of locking pins found 'on the bench'.

Airbus would not have dared suggest this so quickly after the accident without being 100% sure.

[Never Fretter]

Sanus

The implication is one of maintenance error. Again your opinion, but its doesn't rule our design or manufacturing issues.


Soon after the release of this letter strong rumours were leaked about the discovery of locking pins found 'on the bench'.



Unsubstantiated rumours. What makes a rumour strong?:rolleyes:

[Sanus]

NF,

All rumours are unsubstantiated. Otherwise they're called facts.

You pose a good question. I'd say a rumour becomes strong when it passes the taxi driver test.

[kikorro]

I just scrolled the AAIB website to check for the AS 332 to EC 225 LP family accident reports after 2000.
Found 5:
G-REDL crashed with rotor hub separation,
G-REDW and G-CHCN went down under controled ditching following MGB lubrication system fault,
G-WNSB and G-REDU crashed following loss of control or references.

Did I miss something ?

DO
Last october a spanish military As332 crashes near to Mauritania. No survivors, and by now, no known reasons.

They were flying from Noaudibouh to Las Palmas, i think

[Never Fretter]

All rumours are unsubstantiated. Otherwise they're called facts.

There is a similar difference between wild speculation and being able to draw meaningful conclusions.

[TylerMonkey]

Sanus

Again your opinion, but its doesn't rule our design or manufacturing issues..... :rolleyes:

I think you answered your own question.
Why would the manufacturer recommend a return to service this quickly if they HAD NOT (in their own minds) ruled out design or manuf issues. Seems like a logical conclusion, would be very negligent to proceed if they think there is any chance a defect of theirs will come back to bite them. I wonder how many lawyers are advising them . . .

[donut king]

I think you answered your own question.
Why would the manufacturer recommend a return to service this quickly if they HAD NOT ruled out design or manuf issues. Seems like a logical conclusion, would be very negligent to proceed if they think there is any chance a defect of theirs will come back to bite them. I wonder how many lawyers are advising them . . .

Why would a manufacturer ground their type without proof of a design/ manufacturing failure?

Airbus is standing behind their product until it's proven, possibly, to be defective.....imho

[aeropierre]

Birmingham - never say never! Let's just replace 60% of the helicopters in the North Sea. What do you suggest we replace them with? Guess it would be great if we could replace it with something that is guaranteed not to fail. Even with the guarantee, the cost and down time implementation of this would be astronomically. The retraining(hopefully) of everyone from drivers, maintenance, ramp staff to passenger and management would be astonishing. Now minus the guarantee of a perfect aircraft, because that does not exist, I think the safety factor would drastically decrease with drivers that have limited experience of type, engineers that are fixing aircraft they are as familiar with and even ramp staff doing daily operations around aircraft they are not use to. The downtime and limit aircraft support while waiting for aircraft to be manufactured and staff ramped up would have oil companies crippled for passenger movements. The spin off to this would have massive consequences, from cost, fatigue, moral, etc.
A very rare an intelligent comment in this helicopter world .I agree 100%.

[Audun]

Civil defence looking for gear box parts using metal detecors in rough terrain
Søker etter årsaken til Turøy-tragedien - NRK Hordaland - Lokale nyheter, TV og radio (http://www.nrk.no/hordaland/soker-etter-arsaken-til-turoy-tragedien-1.12935553)
The AIBN says it "feel we need more parts" says the leader of the investigation

[FNTC]

From that link:
" Vi er kjent med at rotoren forlot helikopteret, og vi søker å finne alle de komponentene som kan fortelle oss litt om hvorfor det kunne skje. Da er girboksen et sentralt punkt, sier granskingsleder Kåre Halvorsen.

Translation:
"We are familiar with the fact that the rotor left the helicopter, so we are trying to find all the components that can tell us something about why that could happen. In that sense, the gearbox is a central point, says head of investigations, Kaare Halvorsen."

[TylerMonkey]

Why would a manufacturer ground their type without proof of a design/ manufacturing failure?

Airbus is standing behind their product until it's proven, possibly, to be defective.....imho

In most cases I would agree. This one is different, Airbus has G-REDL a previous gearbox event. Combined with the fact that gearbox parts are still missing now and being searched for would make me assume (IMO) that they would hold off approving flight. The fact they released the letter suggests they found physical evidence that is not in the wreckage solely. Whatever they found is not in the missing wreckage, that's a given. And they seem to have decided it won't change their opinion on present flight safety when all the wreckage is finally recovered, again IMO.
I see 3 locations, recovered wreckage, missing wreckage, and gear in maintenance facilities. Recovered wreckage is incomplete, that alone may not answer all the questions. Missing wreckage may help to solve the puzzle but they don't have it. There is only one conclusion I can see logically . . . they found something outside of the wreckage evidence that made them issue this advisory that the 225 is safe to fly. I don't buy the theory that it is all PR spin to keep business as usual. My 2 cents, and worth as much.

[etudiant]

In most cases I would agree. This one is different,
Missing wreckage may help to solve the puzzle but they don't have it. There is only one conclusion I can see logically . . . they found something outside of the wreckage evidence that made them issue this advisory that the 225 is safe to fly. I don't buy the theory that it is all PR spin to keep business as usual. My 2 cents, and worth as much.


That seems very plausible. Also, I can't imagine that either their lawyers or the various regulators would allow such an assertion if they did not have strong grounds.

[G0ULI]

McDonnell Douglas insisted for quite some time that the original DC10 cargo door was quite safe when operated correctly, except when wear and tear of components gave faulty indications that the safety interlocks were engaged, when they weren't.

As aircraft age under real life operating conditions, parts can age and degrade in ways that were not anticipated by the manufacturer.

[TowerDog]

. . they found something outside of the wreckage evidence that made them issue this advisory that the 225 is safe to fly. I don't buy the theory that it is all PR spin to keep business as usual. My 2 cents, and worth as much.

Airbus came to the scene, did a quick inspection and concluded it was not their problem, good to go.

One can only speculate what they found and it was probably not a design fault.

[rotor-rooter]

Airbus came to the scene, did a quick inspection and concluded it was not their problem, good to go.

One can only speculate what they found and it was probably not a design fault.

This would seem to be a very reasonable assumption Towerdog. Unfortunately for Airbus, until they share that information with the general public, no-one is going to want to fly in it. Operators, Customers, offshore workers, and on it goes.

A review of Bill Chiles criteria for a safety assessment that it was safe for his family and grandchildren to fly in, remains the basis that every person involved will continue to use.

There are very few Airbus employees that have spent any time ever flying in a 225, let alone exposed to the offshore environment. I think many people have that in mind when these statements come out.

[henra]

Forget the AH and DGAC noise, they are simply covering their backsides and are totally untrustworthy. The stakes a very high and they are trying to save a product line here.


Hmm, although I still wouldn't bet any money on either cause (suspension bar vs. Gearbox vs. anything else) I can't really follow this reasoning.
How would all of this help if one week later it comes out it was indeed a gearbox failure?
Do you think deliberately deceiving people to gain just one or two weeks would help longterm sales of the 225? Do you buy your 20Mio$ stuff just upon sentiment of the week?
Do you assume exactly this week someone will buy 20 AH225 when he wouldn't have done so if it wasn't declared safe to fly again by the Manufacturer? I don't see how this would help the 225 in the long term. The cause will be found and that will then be the basis for the future. Assumption of the week is meaningless.


Again: What is the benefit of re-assuring yourself it was a certain cause when the experts are still digging through the wreckage. And until we really know the cause from the investigators it might be a good idea to keep the 225 on the ground or at least stick closely to the EASA Safety Bulletin.

[Heathrow Harry]

You need to also consider the possible knock-on effect of grounding every 225.

All those offshore platforms require operating and maintenance crews to not only to keep running but also to stay safe - theoretically you could go back to boat transfers but that's a hell of a lot more dangerous than using a helicopter

[TowerDog]

. This would seem to be a very reasonable assumption Towerdog. Unfortunately for Airbus, until they share that information with the general public, no-one is going to want to fly in it. Operators, Customers, offshore workers, and on it goes.

I would not fly in those things either if there was even a remote possibility the main rotor would detach under normal operations.
(Yes, we don't know the cause yet, but I don't care what the cause is, sloppy maintenance, metal Fatique, etc., I would still not strap by arse into a 225 if there was other choise, and there usually is)

[Satcomm]

I would not fly in those things either if there was even a remote possibility the main rotor would detach under normal operations.
(Yes, we don't know the cause yet, but I don't care what the cause is, sloppy maintenance, metal Fatique, etc., I would still not strap by arse into a 225 if there was other choise, and there usually is)

Tower Dog, I'm not sure what you do for a living but I hope it does not involve flying in a helicopter. If so, what i am about to inform you may shock the hell out of you. There is NOT a single helicopter manufactured that does not have a "remote" chance of the main rotor head departing the airframe. In fact, ALL Helicopters (including theentire super puma family) are designed to retain the main rotor head under "normal" operating conditions. The super puma (225 and 332), are not the first helicopter types to have had the rotor head depart. It has happened to everything from Enstroms, S76s to super Pumas. Put that aside, the main rotor head departing the aircraft is only ONE and very remote way that a helicopter ride can become fatal.

Speculation, discussions and rumours aside, This has been a very tragic event and today my heart does go out to tall the mothers involved and surrounding this tragedy.

[etudiant]

I do think the burden of proof is on Airbus after their statement. Clearly it aims to restore the 225 to routine service asap.
The rotor pulled off one of their aircraft which killed 13 people, but they give an all clear.
So there must be something substantial that has been found, but not yet released.
Absent some very specific understanding of the cause, it would risk brand killing to issue such a recommendation. Who could trust them again if they are found to be at fault?

[EDML]

I think so, too.


Of course the AIBN needs to conclude the investigation before anything is published.


Airbus will not talk about the reason because they are a party in the formal investigation, too.

[henra]

I would not fly in those things either if there was even a remote possibility the main rotor would detach under normal operations.


Bad news for you: There is a (very)remote possibility for the Main Rotor to detach in flight under normal operations in practically any helicopter.

(You loose a part of a blade or a pitch change link comes loose or something major in your MGB brakes and chances are -bye bye to the big ceiling fan above you). Fortunately this happens very rarely. But it has happened in the past and in all likelihood will do so in the future.

[SASless]

Several comparisons of this grounding of the 225 to Airlines not grounding whole fleets of Airliners after a crash.

If a Wing separates from the Airliner during cruise flight in nominal weather conditions and a similar Video was published.....would there be a grounding of the fleet you wonder?

The Dreamliner by Boeing had some electrical problems and encountered a grounding order as I seem to recall (or is my alcohol ravaged brain confusing events somehow?).

Just how much design criteria and manufacturing processes must MGB's have in common before they are considered similar enough to be considered the "same".

[TowerDog]

. Bad news for you:

Nope, not for me. Don't fly choppers and don't ride in them anymore.
If I did, would stay away from certain types, I don't blame the oil workers one bit.

[jimf671]

I haven't yet seen anything that would keep me out of a EC225.


(SAR rescuer/passenger, NS offshore passenger, ...)

[TowerDog]

. I haven't yet seen anything that would keep me out of a EC225.


You are a better man (or woman) than me.
I saw a video of the spinning rotor flying away like a frisbee while the rest of the chopper went into a 9 second dive hitting the rocks at close to 200 mph.
That was enough to keep me out of the EC225. Guess I turned into a chicken on my old days. :sad:

[Bladestrike]

I haven't yet seen anything that would keep me out of a EC225.


(SAR rescuer/passenger, NS offshore passenger, ...)
Same, wouldn't think twice about it.

Over 4,000,000 flight hours? I think the odds of getting struck by lightning are 700,000 to 1.

[Twist & Shout]

Same, wouldn't think twice about it.

Over 4,000,000 flight hours? I think the odds of getting struck by lightning are 700,000 to 1.

I don't think there are many EC225 pilots that have seen the rotor system "first solo" video and wouldn't think about it during their next EC225 flight. Like me, most would strap one on tomorrow if that was the situation, but think about it I would.

There are two components to risk, plus the emotional aspect.

1. Likelihood. (In your lightening statistics, it probably includes those that play golf during thunderstorms. Unlike the tragic accident being discussed where nothing the pilot can do will change their odds, or the outcome.) Without a cause being identified, it's like playing Russian Roulette with thousands of chambers, but an unknown number of bullets. Like most on PPRuNe, I have no idea what went wrong in this case. Is it impossible that it's discovered that every EC225/L2 gearbox will fail under certain life/environment conditions? (Less than the currently mandated replacement schedule. Perhaps a part that currently isn't "lifed", and is reused during overhaul. Just saying it's not impossible, with our current knowledge.)

2. Outcome. Some people are struck by lightning and suffer few consequences.

3. Emotional. Even though I'm more likely to be killed driving to work, no motor vehicle crash offers 10+ seconds of terror, with certain death the outcome.

Given an option, I'd personally prefer to fly a machine type, that didn't have a proven history of unexplained catastrophic failures.

[TowerDog]

As per Google:

. Your odds of being struck by lightning this year are 1 in 960,000. In your lifetime those odds drop to about 1 in 12,000. Your odds of being struck by lightning twice in your lifetime are 1 in 9 million, which is still a higher chance than winning the Powerball.Jan 13, 2016

[Miles Gustaph]

Gents, all this talk of lightning... have you factored in the possibility of triggered lightning?

[HeliComparator]

Given an option, I'd personally prefer to fly a machine type, that didn't have a proven history of unexplained catastrophic failures.

So would I. But since the EC225 doesn't have a proven history of unexplained catastrophic failures I'd be happy to fly that type. There is one currently unexplained catastrophic failure - it is in the early stages of investigation so can it be surprising that it is "officially" currently unexplained?

As to whether AH is currently deliberately misleading customers as part of some defensive death-throe, this seems unlikely but what is more certain is that EASA wouldn't be complicit in that. If there was evidence of a serious design fault that could lead to a probability of a repeat of the accident, EASA would surely have grounded the fleet as part of their AD, rather than merely requiring some fairly superficial checks to be carried out.

[Twist & Shout]

HC

Fair points and valid points Sir, so allow me to rephrase:

Given an option, I'd personally prefer to fly a machine type, that doesn't have a recent history of one presently, and understandably due to ongoing investigation, unexplained catastrophic failure.

I love flying the EC225, it's, in my opinion, a great machine. I've always felt very safe in it.
I'll never forget the feeling I had watching that video of the rotor system in flight. I'm not sure I'll ever feel the same airbourne in the Puma series again. Time will tell. (A lot of things)

Fly safe, smile at every suitable opportunity.

[SMW72]

May eat my words on this but not buying the missing diaper pin theory. Mainly due to the length of time between the accident and the MRH/MGB replacements. Having worked in the industry long enough, find it really hard to believe, at this time with all the safety nets, such a critical part would be missed. The first engineer would have to forget, the second engineer (initialing the independent) would either have to have gained enough trust in the first guy not to look, however, I cant imagine he wouldn't at least asked (which is when you would think the first guy would go "oh $#%&"). There would most likely be a checklist/greasy thumb copy of the major component replacement that gets attached to the work card where someone checked installing the pins (again "oh %$^*, I forgot the pins). Now this is just the 2 guys signing for the job, there would be several other engineers involved in replacing either of the above 2 components, possibly even a shift change (maybe not for MRH) where another set of guys would have been involved. After all that, hangar/stand cleanup, I think someone would have noted a firewall panel, washer and 2 diaper pins left over and questioned why.


So all that got missed, the aircraft has been flying for a month (according to the rumors) since the MRH replacement. There would have been a significant amount of daily inspections, preflights and turnarounds in which no engineer picked up of the missing panel. I realize its down in the bottom of the firewall behind the engine but I think it would be picked up on a daily. Engineers minds are trained to pick up on the anomalies not the thing that are correct. Again, after all that time, someone is now just noting the significance of the parts sitting in the hangar ... I don't know guys, really seems far fetched to me.


I guess nothing is impossible but its not like this is HS's first go at a puma. I do not work for HS but I do think they are a probably the most experienced super puma operators out there. CHC like all the other big boys, have all the known safety nets in place and is just hard to think such a small yet critical step creeped through the cracks for so long.


Obviously like everything else on here, this is just my own speculation and in due time we will hopefully find out the true cause so that the chances of it happening again are minimised.

I don't disagree with much you have written but I've not heard anything about the heat shield being found in the hangar workshop. This has only come up on this forum and has gathered arms and legs. The rumour that was first put forward was that the washer and nappy pins where found but this not to say that they came off this aircraft or they weren't replaced because they were U/S and hadn't been put in the bin.
The other misconception is with regards the inspection process. You may be looking at it from a UK point of view which make your assertions spot on but in Norway engineers can Dupe their own work so an independent inspection is never required under their legislation. This may seem ridiculous to many on here but it is how it is.
But as many have said on here we are all just listening to rumours and it may be a long time before we know the correct details.
My thoughts are with the families of those affected by this tragedy.

[HeliComparator]

T&S

The problem with your philosophy is that it means you would be happy to fly a brand new type with no history, which nevertheless inevitably has some major design defects, over a type that had known issues that have been satisfactorily addressed. I suggest this is based on emotion not logic.

Yes the video was awesome in a scary way, but the fact that there was a visual record of the catastrophe is only an emotive factor, not a "scientific" one. Pilots are supposed to be cool and logical!

[Twist & Shout]

HC

I have a proven history of flying what ever I feel I have to fly to pay the bills.
I'm overly cool and logical.

I think it's pretty unemotional and factual, that at this time there is an unexplained catastrophic failure involving EC225. (Perhaps it would be irrational to be happy to fly an EC225 under the current circumstances, even for say, SAR.)

At this time, I'd rather fly an AW139 or S92, as the catastrophic failures those types have experienced have been explained and mitigated. (As far as I understand.)
Soon I expect the EC225 to return a similar status.

[212man]

Gents, all this talk of lightning... have you factored in the possibility of triggered lightning?

Miles, the talk of lightening is in relation to statistical probability - not to any suggestion it was instrumental in the accident.

[Satcomm]

SMW72, the inspection plate being found in the hangar was mentioned but really holds weight in my rant with the fact of continued missed inspection (not seeing the that the plate was missing).


I've heard the same from a number of different people now. Washer, nappy pins and possibly the round fire wall panel still in the hangar.

[jimf671]

Wanting a type with a different history may be a problem. The alternatives all have significant risk factors but many have not been so publicly aired.

[SASless]

As I choose not to play Golf during a Thunderstorm....or swim with Sharks while holding bleeding meat in my hands...or ride in a VW Micro Bus while Troglidita drives....I can choose what Aircraft I fly to earn my living.

Usually it is not the type of aircraft but the operator that makes the most difference and their version of what constitutes adequate maintenance.

Not suggesting that is the case here.....but it one of the possible explanations as we found in the previous Group Rotor Blade Chunking Contest Win by EC.

We have crafted complex methods in efforts to prevent these tragedies but somehow no matter what we do there is something that happens to trip us up in achieving that goal.

The Human/Machine Interface relies upon perfection in the Human.....and that is where it all runs up on the rocky shore.

[SMW72]

SMW72, the inspection plate being found in the hangar was mentioned but really holds weight in my rant with the fact of continued missed inspection (not seeing the that the plate was missing).

Ok. I stand corrected. I must have missed that thread. Sorry.
But again, none of this has been confirmed by the investigators? So...rumour?

[RVDT]

We have crafted complex methods in efforts to prevent these tragedies but somehow no matter what we do there is something that happens to trip us up in achieving that goal.

Its called Risk compensation. Weird human failing.

Risk compensation (https://en.wikipedia.org/wiki/Risk_compensation)

The "offshore business" is high risk by its nature and probably always will be.

Some may have forgotten.

[taxying]

Twist & Shout
“I think it's pretty unemotional and factual, that at this time there is an unexplained catastrophic failure involving EC225. (Perhaps it would be irrational to be happy to fly an EC225 under the current circumstances, even for say, SAR.)”

T&S. Can I assume your meaning of “happy to fly an EC225” is an expression of your accceptance to fly the aircraft whilst not being comfortable with so doing ? Or vice versa ??

I believe there are three groups of EC225 pilots out there. Those who will fly it on SAR , those who will not fly it at all (or at least until a definitive cause is established) and those who are as yet undecided (or who are in a position where they do not have to decide right away).

I am personally in the latter group and am extremely conflicted about the issue.

Unfortunately the various AUTHORITIES/COMPANIES/MILITARY are in disagreement as to flying the aircraft. All have a different outlook.
As in :-
1. Nil commercial flights
2. Nil passenger flights but SAR is ok
3. Nil flights what so ever

A pilot normally assesses a myriad of factors before he accepts a flight. If he cannot come up with tics in all the boxes then it is a NO GO.

My question is , how can any pilot put tics in all the boxes when there is still an unknown as to whether it was a MAINTENANCE failure or an OEM failure irrespective of what category of flight it is. How can any AUTHORITY/COMPANY/MILITARY condone the release of the aircraft given the above unknown.

Category of flight is irrelevant. Empty ? SAR ? Makes no difference! At the very least there are still “two joes” sitting up front flying a machine with a potential “unexplained catastrophic” fault.

[buzz66]

You just have to stand under the rotor while it's running to know there are some bad Harmonics going on there somewhere.
That in itself can only lead to fatigue issues in the long term.

Fix that terrible Kidney bashing beat the piece of Junk produces and you might have a half decent helicopter

[Noiseboy]

For those who quote the 4 million hours figure, Total Super Puma fleet hours at the end of 2015 were over 5.2 million, the 4 million are mk1, 730k on mk2 and 546k on 225.

[RVDT]

How can any AUTHORITY/COMPANY/MILITARY condone the release of the aircraft given the above unknown

Apparently all of them except CAA UK and Norway.

[AW009]

Might the tripod solution and the retention of the bolts by washer and nappy pins be fundamentally a bad design? Why does an office chair have five legs and why circlips have been invented being more resistant to axial forces and to wear by vibrations? A Cotter Pin 'Fokkernadel' is not constructed to transfer larger forces and the washer is like a punching tool.
Please see https://www.yumpu.com/xx/document/view/55479835/fokker-nadeln

[zouba]

AW009
Easy to criticize a design after a crash...
What is preferable ? Fragile circlip or ductile safety pin...?
To be honest, over the time, it is difficult to say.

[AnFI]

three rods all of which are required to work at the same time for a successful result is a long way from the redundancy concept

[FiveGirlKit]

The other misconception is with regards the inspection process. You may be looking at it from a UK point of view which make your assertions spot on but in Norway engineers can Dupe their own work so an independent inspection is never required under their legislation. This may seem ridiculous to many on here but it is how it is.


Really? Norway applies the same Airworthiness rules as the rest of Europe, and both Part M and 145 require independent checks and critical task error management philosophies. Having the same guy doing his own duplicate inspections doesn't seem to achieve the same safety level.

[zalt]

three rods all of which are required to work at the same time for a successful result is a long way from the redundancy concept

Some other designs put the whole load through a single highly stressed MGB casing.

[EDML]

three rods all of which are required to work at the same time for a successful result is a long way from the redundancy concept

A helicopter does not have a lot of redudancy at all. There are hundreds potentially fatal single points of failure.

[lowfat]

EC225 Main Rotor Head and Main Gear Box Design - Aerossurance (http://aerossurance.com/news/ec225-main-rotor-mgb-design/)

[roundwego]

Might the tripod solution and the retention of the bolts by washer and nappy pins be fundamentally a bad design? Why does an office chair have five legs and why circlips have been invented being more resistant to axial forces and to wear by vibrations? A Cotter Pin 'Fokkernadel' is not constructed to transfer larger forces and the washer is like a punching tool.
Please see https://www.yumpu.com/xx/document/view/55479835/fokker-nadeln

Office chairs with five legs !!!! What office do you work in?

Three legs provide perfect stability. Have you never been in a restaurant at a table which rocks from side to side? Chances are it had four legs. Remove one leg and it will be rock steady.

Seriously, at the end of the day, any helicopter has to have a system which suspends the fuselage from the rotor head. The three support rod system has been in use for decades without problem. If it is designed, fitted and maintained correctly and there are no faults with the materials then it as as good as you will get.

Don't forget the barbecue plate is also a stressed component.

[SASless]

Sorry....not Risk Compensation at all.

That would suggest becoming immune to there risk over time.

What I am talking about is Mr. Murphy and all of his Cousins that constitute the Human Being that is the weak link in the Safety Process.

There is no accounting for how dedicated some folks can be at thwarting the best designed set of procedures, policies, and practices....as often by sheer randomness as much as with malice aforethought.

The rest of your referenced concepts also hold true.

[Lonewolf_50]

@roundwego: How many fasteners attach the BBQ plate to the transmission deck?
Also: just FYI, three of the four office chairs in my house, and most of the office chairs in the office where I work, have five rolling wheels. It appears to have become a standard among certain office furniture manufacturers.

For lowfat: link was very informative/useful.

[riff_raff]

three rods all of which are required to work at the same time for a successful result is a long way from the redundancy conceptWith regards to failure modes/effects, "redundancy" and "single point failure" are not really the best terms to use. Like all other aircraft, rotorcraft systems/structures are designed to provide a specific level of fault tolerance (zero, single, or dual fault tolerance) based on a criticality designation for the function, classification of the failure condition (no safety effect, minor, major, hazardous, or catastrophic) and the probability of the failure mode (probable, extremely remote, or extremely improbable) determined by a failure mode effects analysis (FMEA).

For example, there are numerous components on a rotorcraft, such as the main rotor shaft, performing a function designated as "critical", which have no fault tolerance (or redundancy), and the failure of which would likely be "catastrophic". But it is acceptable if a catastrophic structural failure of the component can be shown to be an "extremely improbable" event by FMEA. Of course, this is based on the fact the FMEA takes into consideration that the component will receive special analysis (fracture, fatigue, etc) during design, special QA processes during manufacture, and special monitoring/inspections during service.

[SASless]

this is based on the fact the FMEA takes into consideration that the component will receive special analysis (fracture, fatigue, etc) during design, special QA processes during manufacture, and special monitoring/inspections during service.

More importantly.....it presupposes no failures in any of those processes at any point during the life of the aircraft and its affected parts.

[RVDT]

Sasless,

Depending on who you talk to coming to unsavoury and unfortunate end hasn't changed in the UK
since the 13th century!

[Pltnorway]

The other misconception is with regards the inspection process. You may be looking at it from a UK point of view which make your assertions spot on but in Norway engineers can Dupe their own work so an independent inspection is never required under their legislation. This may seem ridiculous to many on here but it is how it is.
But as many have said on here we are all just listening to rumours and it may be a long time before we know the correct details.
My thoughts are with the families of those affected by this tragedy.

Really? Norway applies the same Airworthiness rules as the rest of Europe, and both Part M and 145 require independent checks and critical task error management philosophies. Having the same guy doing his own duplicate inspections doesn't seem to achieve the same safety level.

This is not correct. The same rules apply in Norway. Duplicate inspections are required.

[matkat]

Plt i think you are mistaken duplicate and independent several years ago I was the QAM of a now defunct small airline and whilst auditing a work pack noticed that the same engineer was indeed duplicate inspecting his own work when I pulled him up on it and I quote 'we can do this as long as we go for a coffee after the first inspection' the job was fitting a propeller.So unless things have changed in recent years the original quote was correct.

[roundwego]

@roundwego: How many fasteners attach the BBQ plate to the transmission deck?
Also: just FYI, three of the four office chairs in my house, and most of the office chairs in the office where I work, have five rolling wheels. It appears to have become a standard among certain office furniture manufacturers.

For lowfat: link was very informative/useful.

BBQ plate has lots of fasteners, don't know exactly how many. I am not suggesting the fastness became detached, just trying to illustrate that there are many other failure modes than the support struts and their attachment points.

Ref. Office chairs, I guess you are talking about the single leg with five feet ones.

[AW009]

Office chairs, I guess you are talking about the single leg with five feet ones. Let’s say truss elements, mechanical the very same result as a „penta-pod“.

[Beaucoup Movement]

Office chairs with five legs !!!! What office do you work in?

Three legs provide perfect stability. Have you never been in a restaurant at a table which rocks from side to side? Chances are it had four legs. Remove one leg and it will be rock steady.


roundwego, loving your comments! :) so true though. It seems to happen to me 9 times out of 10 at a restaurant/cafe. Quick fix folding a napkin & putting it under the affected leg & works every time! Sorry to divert from the main topic of discussion people but its nice to break the ice a little from time to time. A little humour does go a long way!

Also, I've yet to see someone on here who uses there real name! Someone must have? Chances are a lot of us know each other already or heard the name. Plus there probably wouldn't be as much criticsim amongst eachother!! It would be interesting though :hmm:

[SMW72]

This is not correct. The same rules apply in Norway. Duplicate inspections are required.

As long as a break is taken between the original and duplicate inspection then the same person can carry out both according to Norwegian regs. Unless this has changed recently then that is still the case.

[rans6andrew]

3 legged chairs don't rock but the legs need to stick out much further to give stability against tipping over. 4 legs don't need to stick out as far and 5 legs can stick out less again, for the same stability. It's all about the size of the footprint and the amount of material used in the construction. After that the number of legs starts to add to the amount of material used and is less cost effective. Having more legs does not mean that each leg can be less solid as any 2 legs need to be able to support the weight at the point of tipping over. Of course, once you get more than 3 legs you need to have a flat floor to stand it on to prevent rocking.

[AW009]

@Beaucoup Movement: Truss elements are characterized by being fixed at both sides. Sad to say this will differ sometime in helicopters. We are debating applications of forces, bending loads, shearing forces, vibrations and redundancies (!!!) and no coasters under a table-leg.

Regardless to your graspable sense of humour, your theory is misleading in Newtonian mechanics. But not only by Newton I insist in a ’Penta-pod’; for each rotor blade one leg (suspension bar):rolleyes:

[Fareastdriver]

3 legged chairs don't rock but the legs need to stick out much further to give stability against tipping over. 4 legs don't need to stick out as far and 5 legs can stick out less again,

The Alexander Kielland was a 'penta' semisub; i.e. it floated on five circular pontoons. When one leg support failed it capsized with the loss of 123 lives.

https://en.wikipedia.org/wiki/Alexander_L._Kielland_(platform)

[212man]

Following the tragic Norwegian Super Puma helicopter accident on Friday 29 April, the UK and Norwegian Civil Aviation Authorities have been collaborating very closely and are united in their approach.




Shortly after the accident, both organisations introduced restrictions to the Airbus EC225LP helicopter to prevent operators using it for commercial flights. Both organisations have now also agreed to extend the scope of the restriction to include the AS332L2 Super Puma helicopter until further information is available. The decision to extend the restriction is based on the close similarities between the two types of helicopter and neither helicopter can be used by either UK or Norwegian operators for commercial flights.

The restrictions do not apply to search and rescue flights.

The accident remains under investigation by the Norwegian authorities and we remain in close contact with all offshore helicopter operators to continue to assess the situation.


The Norwegian CAA and UK CAA introducing restrictions to the AS332L2 Super Puma - (http://luftfartstilsynet.no/caa_no/The_Norwegian_CAA_and_UK_CAA_introducing_restrictions_to_the _AS332L2_Super_Puma)

[Peter3127]

Three legs provide perfect stability. Have you never been in a restaurant at a table which rocks from side to side? Chances are it had four legs. Remove one leg and it will be rock steady.

@Roundwego .....

Strange but True: Turning a Wobbly Table Will Make It Steady - Scientific American (http://www.scientificamerican.com/article/strange-but-true-turning/)

:}

[PJ2]

I have read the entire thread with great interest (fixed wing transport pilot, (ret'd), not a heli pilot), and have a basic question in re the missing pin theory - has the presence of all three (six, really) suspension rod-end pins with their two "nappy" retaining pins been confirmed yet? Are there any remnants of the barbecue plate attached to any of the three rods?

Re the loss of one of the three points of suspension and retaining control over the machine, the chair examples are, of course, in compression - if we are suspending a load from three points and one point breaks, the "system" will take up a new physical position defined by the two remaining points of suspension and the vertical loads, (plus the complex mixture of loads offered by the rotating mass as the rotor "disc" changes position), unless some vertical load-bearing capability is retained, if even for a short while, by the MRH/MRG structure, (familiarity with these components only gained by the descriptions of the structure as posted or linked on the thread).

PJ2

[AW009]

@Fareastdriver: Do you want to tease me, do you? Or would you even tell me the five pontons of the “penta-platform Alexander L. Kielland“ had been fixed non-positive (by mechanics, e.g. by bolts & nappy pins) direct to the ocean bottom?
Please take notice: For AS332L2 Super Puma I insist as optimum in a ’quatro-pod’. Don’t wonder why? Mnemonic might be the answer.

@212man:„Shortly after the accident, both organisations introduced restrictions to the Airbus EC225LP helicopter to prevent operators using it for commercial flights. Both organisations have now also agreed to extend the scope of the restriction to include the AS332L2 Super Puma helicopter until further information is available“.

Congratulations to both organisations for their hard-line posture.:ok:

[Keepitup]

Sorry, I am abit confused.
Isn't Norway part of EASA ? and the maintenance carried out iaw Part145
Therefore how come you have different regulations relating to Independent Inspections !
I have heard of this practice in the USA but never in EASA Land


Can someone please explain

Sorry, I retract my above comment, I thought Norway was under EASA Regs. My apology.


Keepitup

[industry insider]

212 Man

Very interesting.

I wonder if they are beginning to see evidence of a similar failure mode to REDL in 2009? I hope not.

[jccmj1]

Can't be a Sus Bar failure because the Gearbox split in 2 parts.
Sus Bar or Pin failure would see the Barby Plate and whole gearbox leave the scene. Almost has to be major Gear failure internal to the Gbox.
I bet my bottom dollar they are the bits they want to still find.

If the front suspension bar becomes loose, the engines will hold the bottom of the mgb from the front. Since it's not really designed to work that way, it will eventually separate.

[SMW72]

I have read the entire thread with great interest (fixed wing transport pilot, (ret'd), not a heli pilot), and have a basic question in re the missing pin theory - has the presence of all three (six, really) suspension rod-end pins with their two "nappy" retaining pins been confirmed yet? Are there any remnants of the barbecue plate attached to any of the three rods?

Re the loss of one of the three points of suspension and retaining control over the machine, the chair examples are, of course, in compression - if we are suspending a load from three points and one point breaks, the "system" will take up a new physical position defined by the two remaining points of suspension and the vertical loads, (plus the complex mixture of loads offered by the rotating mass as the rotor "disc" changes position), unless some vertical load-bearing capability is retained, if even for a short while, by the MRH/MRG structure, (familiarity with these components only gained by the descriptions of the structure as posted or linked on the thread).

PJ2

The suspension bars don't attach to the barbeque plate. They attach to the gearbox at one end and the aircraft structure at the other. The bottom of the gearbox is the only thing that attaches to the barbeque plate and the barbeque plate is attached directly to the transmission deck at two different points fwd rh and aft lh. Both of these points are attached through the airframe. Hope this helps?

[matkat]

Keepitup, you can only understand my confusion on this especially concerning when I asked the UK CAA for guidance which was duly sent which I showed the accountable Manager who advised 'thats not how it is done here' I left shortly after that.

[matkat]

But how could that possibly be controlled again think difference between duplicate and independants and more concerning how the NCAA can bypass top level requirements of EASA

[AW009]

Berlin/Oslo (dpa) - Der Absturz eines Eurocopter-Hubschraubers an der Küste Norwegens hat nach Angaben der deutschen Luftwaffe keine Auswirkungen auf die Flugbereitschaft der Bundeswehr. «Das in Norwegen eingesetzte Modell H-225 Super Puma - auch Eurocopter EC 225 - haben wir nicht im Bestand», sagte ein Luftwaffensprecher am Samstag [30. April 2016] der Deutschen Presse-Agentur in Berlin. «Es ergeben sich daher keine Konsequenzen, irgendwelche Überprüfungen an unseren Helikoptern [Cougar AS-532-L2] durchzuführen oder gar den Flugbetrieb mit Hubschraubern der Flugbereitschaft einzustellen.»

Translation: Berlin / Oslo (dpa) - According to the German Air Force, the crash of a Eurocopter helicopter on the coast of Norway, does not affect the Special Air Mission Wing of the German Ministry of Defence (BMVg) to the Bundeswehr (German armed forces). «The Model H-225 Super Puma - Eurocopter EC 225 operated in Norway we do not have in stock,» an Air Force spokesman said on Saturday [30th of April, 2016] to the German Press Agency in Berlin. «Therefore no consequences are resulting to execute any savety inspections on our helicopters or even suspending flight operations with helicopters [Cougar AS-532-L2] of the the Special Air Mission [and VIP-] Wing of the German Ministry of Defence to the Bundeswehr»

…. paper pusher!:ugh:

[SMW72]

Sorry, I am abit confused.
Isn't Norway part of EASA ? and the maintenance carried out iaw Part145
Therefore how come you have different regulations relating to Independent Inspections !
I have heard of this practice in the USA but never in EASA Land


Can someone please explain

Sorry, I retract my above comment, I thought Norway was under EASA Regs. My apology.


Keepitup

They sort of are but aren't. They are associate members of EASA. They have no voting rights to amend the legislation.

[letmein]

JCCMJ1
If the front suspension bar becomes loose, the engines will hold the bottom of the mgb from the front. Since it's not really designed to work that way, it will eventually separate.

I agree.

Gimbal bearings would feel extreme lateral load and fail. The inside of the transmission would be sprayed with chucks of metal as the gears start to inter-mesh. Epicyclic would jam-up not long after that.

[PJ2]

SMW72, yes it does help, thank you and that makes much better sense! (just north of you at Banff...)

Still of interest is the accounting for all pins and 'nappy' pins - will standby further.

cheers,
PJ2

[Satcomm]

CAAs grounding of the L2 certainly points in a little different direction then the suspension bars or maintenance error. Just my opinion! If they were determined it was an issue with suspension bars or airframe fittings then they may have included the L/L1 (not sure how many are still flying in the NS), however, maintenance error would not warrant the grounding of another type.
Again I may eat my words but have not believed the suspension bar idea from the beginning.

[stbak]

As long as a break is taken between the original and duplicate inspection then the same person can carry out both according to Norwegian regs. Unless this has changed recently then that is still the case.

This is partly true. EASA rules are the main rules. This means independent/duplicate inspections are performed as described in EASA rules.
But, "single person" independent inspection may be carried out, but only if critical safety tasks MUST be carried out at a remote base. (Example).
It is clearly stated in the company MOE / CAME for how to do that.

Norwegian choppers are often grounded due to lack of independent inspectors.
(Often holidays etc). Other AC is then used.
This is to ensure proper and safe maintenance.

I dont know if some "small airlines" are abusing this rule, and signing of critical tasks on a regular basis without having an independent person to do the re-inspection, but I can tell you all for sure that this does not happen in CHC and Bristow.

Loose bolts or missing parts does not make any sence in this case.

[AnFI]

the whole concept is wrong
this is what happens when legislators try and design helicopters

EDML: “A helicopter does not have a lot of redudancy at all. There are hundreds potentially fatal single points of failure.“
quite right, and easy to make these parts reliable as long as the payload isn't wasted on bogus redundancy instead

riff raff: "...rotorcraft systems/structures are designed to provide a specific level of fault tolerance (zero, single, or dual fault tolerance) based on a criticality designation...."
but when you have 3 of something performing one function that all have to work then what do you call that?
You need a new category Triple Fault Intollerant perhaps?

[EDML]

but when you have 3 of something performing one function


OK, what about the rotor blades then? You have 5 pcs but any single failure will surely bring that thing down.


Same for the wings of a fixed wing A/C

[dakarman]

I would like to ask what i hope is not a too obvious question regarding the supposed suspension bar issue, bearing in mind we have already seen the unpleasant video of a mostly intact rotor disk descending on its own.
If the forward suspension bar failed for whatever reason, would this not cause the rotor disk to tilt backwards relative to the body of the helicopter quite possibly at a large angle which would lead almost instantaneously to a loud and brief argument between blades and tail boom which would certainly not leave an intact disk.
Even assuming the mgb took the strain briefly i suspect initially there would be some tilt back then when the epicyclic or whatever failed, the two remaining rear suspension bars would again instantly pull the disk back with the same result.
I dont post often but wondered if this could be clear enough evidence that at least the front suspension rod may not be the cause.
I feel the need to point out that i am not a pilot but a regular slf on these unpleasant machines with a good technical background and strong interest in aviation.

[AnFI]

Post deleted.

This thread is not the place for another attempt to derail the discussion with AnFIs obsession about engine requirements.

Senior Pilot

[Apate]

SP, well done!

[roscoe1]

Dakarman,
(slf= self loading flier??). The problem with speculating to the extent you outline is not that it has no value (all possibilities deserve discussion). It is because there are so many parameters in an accident like this that you have to be willing to accept that although your postulate does make sense, it doesn't take into account the pilot or failure induced reaction of flight controls, gust loading or aircraft attitude at the time of failure or a myriad of other factors that might affect the departure of a massive chunk. There were undoubtedly pieces of MRB missing during the hub's descent and who knows how much or what caused that. Unless someone here knows what the investigators know, I think any of the theories proposed might have pieces of reality. I have seen one tail rotor blade destroyed by a blade strike and the other blade untouched. Anything is possible until you have ruled it out based on all the evidence. ‘Eliminate all other factors, and the one which remains must be the truth.’- S. Holmes, who also said ‘There is nothing more deceptive than an obvious fact.’ and last but not least ‘Having gathered these facts, Watson, I smoked several pipes over them, trying to separate those which were crucial from others which were merely incidental.’ Concentrate on what you have evidence for, not what didn't happen-Me.

[ExGrunt]

@roscoe1:

SLF is generally accepted as: 'Self Loading Freight' ie it walks on by itself.

Not to be confused with 'Self Loading Rifle' a fine infantry weapon beloved by former 'cold warriors' which will stop anything human in its tracks but isn't much good against Daleks or Cybermen if Dr Who is to be believed ;o)

EG

[SLF3]

The marine equivalent of SLF is 'VOB': Voice Activated Ballast. Arguably more useful than SLF, arguably less.

[Rotor Work]

I hope they find the cause of the accident.
RW

From Australian ABC

Offshore workers delayed returning to WA's Pilbara after helicopters grounded - ABC News (Australian Broadcasting Corporation) (http://www.abc.net.au/news/2016-05-12/oil-and-gas-workers-stranded-off-wa-after-helicopters-grounded/7410130)

Oil and gas workers have been left stranded on a rig off Western Australia's north west coast after a fleet of helicopters was grounded in the wake of last month's Norway crash.
Commercial flights of the EC225LP Super Puma helicopter were suspended (http://www.abc.net.au/news/2016-04-30/airbus-grounds-super-puma-helicopters-after-norway-crash/7372882) worldwide by Airbus after the accident near the Norwegian city of Bergen killed 13 people (http://www.abc.net.au/news/2016-04-29/no-survivors-found-after-helicopter-crash-off-the-norway-coast/7372580) on April 29.
Two of the helicopters, also known as the H225, are normally used to transfer workers from the Ocean Monarch drilling rig back to the mainland in the Pilbara.
The company which transports the offshore workers, CHC Helicopters, said it was using smaller aircraft to try to clear the backlog.
However a spokeswoman said the new aircraft could only take between three and five people at a time, resulting in minor delays getting workers home.
The ABC understands some employees have been waiting up to five days for alternative transport.
It is also believed some stranded workers may have been transferred to the mainland by boat - a trip which takes about 13 hours.
The National Offshore Petroleum Safety and Environmental Management Authority said it was aware of the matter and was currently making inquiries with the operator of the Ocean Monarch.
The crash off Norway came after two EC225LP Super Puma helicopters ditched in the North Sea off Scotland in 2012, with all passengers and crew rescued.
Both accidents were blamed on gearbox problems.
The helicopters were grounded in the UK before being given the go-ahead to resume flying in August 2013.
Four people died later that month when a different model of Super Puma, the AS332 L2, crashed off Shetland.

[terminus mos]

So, are they linking the a possibility of the same failure occurring in the L2 as may have occurred on the 225 or are they linking this 225 with the previous L2 epicyclic failure?

[helicrazi]

None of the above, just a$$ covering

[Vibetribe]

http://publicapps.caa.co.uk/docs/33/SD2016002.pdf

[AW009]

@Vibetribe: Simple, logical arguments and procedures which should be acknowledged by every EASA-Member-State.

[riff_raff]

"....but when you have 3 of something performing one function that all have to work then what do you call that? You need a new category Triple Fault Intollerant perhaps?"

AnFI- in terms of FMEA the 3 tension struts are not performing the same function. Each one is performing a separate function, but they are part of a common system. Since an individual tension strut will experience total loss of function due to a single (structural) failure event, the tension strut itself has zero fault tolerance for this failure mode. And since the MRGB attachment system will lose the capability to perform its function due to the failure of a single tension strut, the MRGB attachment system also has zero fault tolerance for the failure mode. If the tension strut and MRGB attachment system perform a critical function required for safe flight and have no fault tolerance for this failure mode, it must be shown by analysis that the failure mode is an "extremely improbable" event.

Here's a relevant section from FAR 23.1309:
"(c) The airplane systems and associated components considered separately and in relation to other systems, must be designed and installed so that:(1) Each catastrophic failure condition is extremely improbable and does not result from a single failure;
(2) Each hazardous failure condition is extremely remote; and
(3) Each major failure condition is remote."


If you have an interest in learning more on the subject I recommend reading FAA AC23-1309-1E (http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2023.1309-1E.pdf). It's not specific to rotorcraft, but the basic principles still apply.

[212man]

Or, of course, you can read the rotorcraft specific document - AC29
http://www.faa.gov/documentlibrary/media/advisory_circular/ac_29-2c.pdf

[riff_raff]

Thanks for the link to AC29-2C.

Of course, the section AC 29.1309(b)(3)(i)(E) regarding catastrophic failure of flight critical systems is similar:"(E) Catastrophic Failure Conditions must be Extremely Improbable."

It's also worth noting that the full FAA AC29-2C document from 2014 is 1258 pages. This is probably many times the number of pages in the FAR 29 regulations at the time the EC225 was FAA certified.

[The Big E]

They sort of are but aren't.


EASA Member States as at July 2014.


Austria, Belgium, Bulgaria, Croatia, Cyprus, CzechRepublic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,Ireland, Italy, Latvia, Liechtenstein, Lithuania, Luxembourg, Malta,Netherlands Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,Sweden, Switzerland, United Kingdom

Regards to ya all. Big E

[212man]

This is probably many times the number of pages in the FAR 29 regulations at the time the EC225 was FAA certified

Bear in mind this is the AC and it addresses Part 29 at its various Amendment states, so with some degree of 'duplication' (for want of a better expression) and is also a guide on 'how to' as opposed to 'what to' so each requirement is expanded upon.

[birmingham]

Despite all the speculation about potential maintenance issues it would seem, as is so often the case, that there is not one blindly obvious explanation for this incident. TBF given HS/CHC's reputation as a top notch maintenance outfit it would be extremely surprising if this was the case.

Despite the pressure the various authorities must be under to release some news or relax the ban, if they felt it was safe to do so they would have surely done so by now. Consequently I'm a bit confused by the statement from Airbus. When they stated on 1 May; "Considering the additional information gathered during the last 48 hours, Airbus Helicopters’ decision, at this stage, is to not suspend flights of any nature for the EC225LP".

Given that the Norwegian and British authorities must also be in possession of this information it is strange that 13 days later they haven't releaxed the ban.

It is unsurprising that the regulators are more cautious than the manufacturer here but they will usual make statements when significant information comes to light. Their statement of 3 May didn't really endorse Aibus Helicoters' comments.

Does anyone know if there are any planned press conferences/announcements or will they not release any information until they feel they have something significant to say?

[birmingham]

The Norwegian CAA and UK CAA introducing restrictions to the AS332L2 Super Puma - (http://luftfartstilsynet.no/caa_no/The_Norwegian_CAA_and_UK_CAA_introducing_restrictions_to_the _AS332L2_Super_Puma)

[SFIM]

Mr Birmingham, according to this link

Helikopter styrtet ved Turøy - NRK Hordaland - Lokale nyheter, TV og radio (http://www.nrk.no/hordaland/helikopter-styrtet-ved-turoy-1.12923962)

which translated says that there will a press conference tonight at 6:30pm norwegian time where the preliminary accident report will be presented by the AIBN.

[birmingham]

Thank you - let's hope some useful evidence has com to light

[G0ULI]

The air accident investigators have to do rather more than just find the cause of an accident. Reporting that a bolt snapped under excessive load or a part was misfitted during maintenance simply identifies the immediate cause of that particular incident. The chain of events leading up to the failure has to be identified and remedial measures suggested to prevent a recurrance. That requires some quite detailed discussions with the aircraft manufacturer and maintenance organisations and possibly lengthy engineering tests before any detailed report will be published.

[Volume]

With all the 1309 discussion it should always be understood, that this is not covering human error, neither during maintenance not during operation. It just covers all technical failure cases which are related to the type desgn.
There are always good chances that human action can cause catastrophic failure.

[henra]

Given that the Norwegian and British authorities must also be in possession of this information it is strange that 13 days later they haven't releaxed the ban.

It is unsurprising that the regulators are more cautious than the manufacturer here but they will usual make statements when significant information comes to light. Their statement of 3 May didn't really endorse Aibus Helicoters' comments.


Indeed, this sustained contradiction is a bit surprising. Possibly AH was a bit too optimistic with their early conclusion based on what was known then and now don't know how to retreat from their statement.
Still it would be quite embarrassing for them should come out that their relatively definitive statement was premature and wrong.

[industry insider]

Birmingham

Given that the Norwegian and British authorities must also be in possession of this information it is strange that 13 days later they haven't releaxed the ban.

As you point out in your next post, they have actually extended the ban to the 332L2.

I am quite prepared to be proved wrong, I would welcome it but I am not going for the bolt/pin/nappy pin theory. I am leaning towards a repeat of G-REDL.

[AW009]

@industry insider: I am the very same opinion as you are: Repeat of G-REDL might be the ’causa’ or the root, the separated rotor head is only the fatal and deterrent effect. But between those is the question of redundancy and the quality of engineering.

[dipperm0]

I know you think you understand what you thought I said but I'm not sure you realize that what you heard is not what I meant'

Alan Greenspan, head of the Fédéral Reserve

[Abdulbandul]

http://www.aibn.no/About-us/Nyhetsarkiv/The-Helicopter-Accident-Preliminary-report?iid=19654&pid=SHT-Document-Attachments.Native-InnerFile-File&attach=1

[Self loading bear]

So it looks the 2 aft suspensions bars were ripped off the fuselage including the foundation hinges. Probably after first failure of either: the epicyclic module or the front suspension bar upper hinge point (and following epicyclic failure or Gear housing after extensive uneven loading)

This makes maintenance mistakes at the difficult to access forward bottom hinge point less probable. Unless the forward suspension bar has not been found on the Main wreckage, and would have broken at two ends.

SLB

[Nadar]

The above link to the preliminary report doesn't work for me, so I'm posting as well: http://www.aibn.no/Om-oss/Nyhetsarkiv/Helikopterulykken-Forelopig-rapport?iid=19664&pid=SHT-Document-Attachments.Native-InnerFile-File&attach=1

[M609]

Google translate news from press conference (With pictures of gears) (https://translate.google.com/translate?sl=no&tl=en&js=y&prev=_t&hl=no&ie=UTF-8&u=http%3A%2F%2Fwww.bt.no%2Fnyheter%2Finnenriks%2FHar-funnet-flere-tusen-deler-etter-helikopterstyrten-3596394.html&edit-text=&act=url)

[Scuffers]

hard to understand the translation...

I read it as suggesting the support bracket bolts may have failed? - or am I reading it completely wrong?

[Lonewolf_50]

From the google translated (Hoping for another translation soon, and tip the cap to those hard working folks on the investigation team:


1) Is that a sun or a planetary gear from the epicyclic? (ouch, look at the damage to those gear teeth!)
2) What is the significance of that electronics box?
3) I see the "nappy pin" still attached to that end of that strut/support. Now have an idea on the size of pins/bolts.

[halsandberg]

This is one of the parts that the Norwegian Accident Investigation Board showed to the public 05/13-2016 regarding the 225 accident outside Tyrøy.
It´s supposed to be engine control electronics.
Why did they show this part?322

[halsandberg]

This is a sun gear from the HC225 that crashed two weeks ago in Norway. The Norwegian Accident Board showed this to the press today, 05/13-2016 - what does the damage on the gear show?/Users/Sandberg/Desktop/sun-gear-225.jpg

[M609]

Prelim AIBN report (english) (http://www.aibn.no/Om-oss/Nyhetsarkiv/Helikopterulykken-Forelopig-rapport?iid=19664&pid=SHT-Document-Attachments.Native-InnerFile-File&attach=1)

[whoknows idont]

A bit irritating that AIBN has turned this into a scavenger hunt...

[halsandberg]

This is a map that shows the position of the main parts after the 225 accident in Turøy, Norway.
The parts of the main rotor is found several hundred meters apart. Why?/Users/Sandberg/Desktop/rotor-spread.JPG

[halsandberg]

This is one of the sun gears from the 225 accident. The Norwegian Accident Investigation Board - Flyhavarikommisjonen - do not comment on the state of the gear. Why not?

[Nadar]

This is probably futile since the delay waiting for moderator approval most likely will mean nobody will see this, but I'll give it a go. A lot of the google translation isn't that bad, so I'll just copy that and improve it where needed.


Found several thousand parts from the helicopter accident

AIBN is still missing vital parts and will conduct further searches around Turøy.

Erlend Jensen Haugen, Hans O. Torgersen, Alf Ole Ask and NTB

Published May 13th. 2016 5:55 p.m.
Updated May 13th. 2016 8:29 p.m.

Around 6:30 p.m AIB presented the interim report of the helicopter accident at Turøy outside Bergen on 29 April, in which 13 people died.

- It's a complicated process and much remains to be done, said department director Kåre Halvorsen.

He said that there has been searched almost continuously in the sea since the accident, and that the search will resume on May 18 (May 17 is the national day in Norway).

- Thousands of parts have been found. Parts are still missing, and we will continue to search for parts we consider important to find, he said.

Accident inspector Tor Nørstegård said that parts found in the sea have already begun to corrode.

- Time is working against us, so it is urgent to retrieve parts from the sea, he said.

http://bt.mnocdn.no/incoming/article3596416.ece/ALTERNATES/w980cFree/tb1ba8dc.jpg?updated=130520161649
http://www.pprune.org//bt.mnocdn.no/incoming/article3596416.ece/ALTERNATES/w980cFree/tb1ba8dc.jpg?updated=130520161649 SHOWED PARTS: At the press conference, parts found after the accident where showed. Deputy Halvorsen stressed that these should not be considered as the cause of the accident. - These are components that are core to the investigation and have gotten most attention, but it is not certain that any of these havetriggered the accident, he said.
Scanpix

Gearbox parts can provide answers

The preliminary report, which can be read here (http://www.aibn.no/About-us/Nyhetsarkiv/The-Helicopter-Accident-Preliminary-report), is about the work done so far and the plans ahead. According to the report, everything was normal until a sudden catastrophic failure occurred. The recordings from the cockpit voice and flight data recorder (CVFDR) stopped when the accident ocurred.

- There are no indications that the pilots' actions played a role in the accident, the report says.

AIBN is particularly keen to gather as many parts as possible belonging to the gearbox, which is the intermediary between the motor and the rotor. These parts might explain why to rotor detached
.
Engine runs at 20,000 rpm, which the gearbox reduces to 265 rpm for the rotor. This means that the gearbox is subject to very big forces.

The gearbox itself was found on land, while the internal gears were found both on land and in the water, Halvorsen informed.

Too early to conclude

This far several thousand parts from the helicopter have been found during searches at sea and on land. We're focusing the search on parts from the gearbox.

- How much of the critical parts are missing?

- We have barely started to put together the picture. It's therefore impossible to say how many parts we lack, Halvorsen said, adding that the more one finds, the more precise conclusions can be drawn
.
He also stressed that it's not given that the parts which were shown at the press conference are components that explain what caused the accident.

- What we have found help us to understand what has happened, he explained.

http://bt.mnocdn.no/incoming/article3596418.ece/ALTERNATES/w980cFree/tb1ba874.jpg?updated=130520161649
http://www.pprune.org//bt.mnocdn.no/incoming/article3596418.ece/ALTERNATES/w980cFree/tb1ba874.jpg?updated=130520161649CORROSION: Accident inspector Tor Nørstegård underlined the urgency of getting wreckage parts up from the sea due to corrosion. One of the parts that were shown was already rusted when it was found, he said.
Scanpix

Will take a long time

Halvorsen told that a lot of analysis work remains. AIBN cooperates with the French and the British AIBs
.
- Several of the parts are to be examined by the English and French commission and in part by the manufacturer under our supervision, aircraft accident investigator Tor Nørstegård said
.
AIBN has not yet started to dismantle the large components. The metallurgical investigations will take a long time.

- The road ahead for us now will be to pack down the critical components, send them and travel with them to wherever they are to be examined further, Halvorsen said.

AIBN was very keen to emphasize that no definite conclusion can be drawn from the material and analyses gathered so far.

http://bt.mnocdn.no/incoming/article3596108.ece/ALTERNATES/w980cFree/rotor3-2.jpg?updated=130520161153
http://www.pprune.org//bt.mnocdn.no/incoming/article3596108.ece/ALTERNATES/w980cFree/rotor3-2.jpg?updated=130520161153 ROTOR: The support bar which helps to hold the gearbox in place and the rotor was found 3-400 meters from the crash site.
RUNE NIELSEN

VG: Rotor and gearbox mounting detached

According to VG (http://www.vg.no/nyheter/innenriks/helikopterstyrten-i-hordaland/helikopterulykken-ved-turoey-stoettestag-ble-revet-av/a/23684006/) (another Norwegian newspaper) the rotor detached together with the gearbox mounting.

The newspaper has gotten information that AIBN has found mounting fixtures to the bolt and the mounting itself, which held the rod attached to the top of the gearbox (I'm really sorry, I know this isn't very clear but neither is the original norwegian text and I'm unable to understand what they are actually trying to say). The support bar which helps to hold the gearbox and rotor in place and the rotor was found 3-400 meters from the crash site.

The AIBN warns not to draw any conclusions from this.

A video taken by an eyewitness shows rotor which was in the air long after the 10-ton helicopter crashed to the ground with 13 helpless passengers aboard.

Last week the helicopter manufacturer Airbus sent a letter to all its customers asking them to check these support rods and how hard they were tightened.

AIBN has since the accident searched with divers for parts of the helicopter that can be of help shed light on what happened prior to the accident.


Disclaimer: The original text is unclear, inconsistant and repetitive. I've rewritten some parts where the intended meaning was obvious to me, but for the most I've just tried to translate as best as I can what were written in the news article. My English knowledge is also limited when it comes to the names of the bits and pieces, and the same seems to be true for the Norwegian terms for the author of the Norwegian text. I've been unable to find a video of the press conferance, which I'm pretty sure would make referring what was actually said by the AIBN much easier. All in all this doesn't bring a lot of new information, and I'd recommend reading the preliminary report instead.

[charlieDontSurf]

Are you a reporter halsandberg?��

[TowerDog]

No news really from the preliminary report, just areas of interest and we are still working on it, etc.

[halsandberg]

Are you a reporter halsandberg?��

Yes, and i am working with the crash story

[henra]

No news really from the preliminary report, just areas of interest and we are still working on it, etc.

What is a bit interesting is the Debris map in the report. A new information for me was for instance that a section of a M/R blade were found at some distance to the M/R.
Rotor and fairings around the rotor are lying far away from the wreckage while especially the second stage gear wheels are marked very close to the impact site. Strangely the first stage gear wheel being found a little bit further away from the point of impact of the main wreckage.


What I find striking is the fact that they can't judge if the front suspension bar separated by force or by losing a pin. With the bits and pieces they have at least this should be identifiable where it separated and if this was due to overload fracture.
For the MGB they are probably still lacking a number of parts of the epicyclic module.

[theblackisle]

Do they actually have the complete Fwd Suspension bar?

[ukv1145]

Is the discolouration pattern on the failed forward suspension bar upper mount indicative of a fatigue crack/cracks prior to failure? Looks possible but I'm no metallurgist.

[epkp]

Is the discolouration pattern on the failed forward suspension bar upper mount indicative of a fatigue crack/cracks prior to failure? Looks possible but I'm no metallurgist.





Answer of your question is in the preliminary report, page 7




"At this preliminary stage of the investigation, detailed metallurgical examinations have not been performed. The examinations so far have not shown any sign of fatigue failure."

[ericferret]

Corrosion sets in very quickly when sea water is involved.
When BO 105 G-AZOM crashed flying out of Strubby it was in the water for less than a day. However by the time the aircraft was examined the corrosion at the point where the tail drive shaft failed made it almost impossible to determine the cause.

[Bubblecopter85]

Forgive me as I'm not an engineer/technical minded, however it seems the two rear sus bars are complete with their mounting brackets (and nap pins still installed), which to me gives impression they've come loose from a/c frame under force.

That leaves the question of the front sus bar, which they haven't shown a full picture of, however they do show the top mounting eyelet (with bolt and pin) that seems to have broken up.

If the bottom of the front sus bar was not anchored as per some of the 'maintenance theories' then surely the bar would have come away with the MR head un-challenged and the top attachment wouldn't have been damaged?

Does the fact it's broken away not indicate that it was still secured at bottom when it separated?

[G0ULI]

The broken parts of the planetary gear indicate that a failure in the main gear box was most likely to be the initiating event. The forward suspension bar mounting looks to have failed under a sudden single stress event although there appears to be some signs of minor cracking or corrosion at surface edges. Detailed examination will be needed to check for beach marks to determine positively that this was not a fatigue crack. Pitting and staining of the parts is most likely due to fire and/or immersion in sea water.

The inertia of the main rotor blade would be sufficient to snap the forward mount in event of the main rotor gear box failing suddenly and jamming.

So very reminiscent of the previous rotor detatchment involving G-REDL.

[Bubblecopter85]

The broken parts of the planetary gear indicate that a failure in the main gear box was most likely to be the initiating event. The forward suspension bar mounting looks to have failed under a sudden single stress event although there appears to be some signs of minor cracking or corrosion at surface edges. Detailed examination will be needed to check for beach marks to determine positively that this was not a fatigue crack. Pitting and staining of the parts is most likely due to fire and/or immersion in sea water.

The inertia of the main rotor blade would be sufficient to snap the forward mount in event of the main rotor gear box failing suddenly and jamming.

So very reminiscent of the previous rotor detatchment involving G-REDL.


Thank you, appreciate your pov.

[birmingham]

The latest update from the AIBN makes it clear that they are not yet able to form any substantive conclusions as to what caused the catastrophic separation of the main rotor head and mast. They are continuing to look for components for their reconstruction. The report if anything makes Airbus Helicopters statement on 3 May seems even more confusing. Nothing I have seen in the brief report remotely suggests that they are focussing on possible maintenance errors any more than the many thousands of other potential causes. It seems that the reason for the crash is lying under the sea or remains to be discovered in many more hours of painstaking investigation. While this happens the Puma's future, at least in the North Sea hangs in the balance. Whether the ultimate conclusion finds that the cause is a failure similar to the previous accidents or another which caused a similar catastrophic separation the machine's customer base is losing confidence. Much of this is unscientific, even emotional, but getting people to feel happy about this aircraft is going to be difficult. it is not really a question of 5 million safe flying hours but the amount of failures in the last few hundred thousand.

https://www.energyvoice.com/oilandgas/north-sea/109441/dossier-journey-north-sea-platforms-now-form-russian-roulette/

[letmein]

Bubble Copter
If the bottom of the front sus bar was not anchored as per some of the 'maintenance theories' then surely the bar would have come away with the MR head un-challenged and the top attachment wouldn't have been damaged?

Does the fact it's broken away not indicate that it was still secured at bottom when it separated?

Not necessarily, if the unsecured front bottom suspension bolt slipped out (2-3 months after installation) the bar would still remain sandwiched between the 2 engine firewalls. After input bearing failure->epicyclic failure, the head would have twisted off, but the bar could have remained stuck between the two firewalls, the top eyelet would have had to bear the brunt of the shear forces and broken off. I'm surprised that there is no picture yet of the bottom bracket area, either showing it intact, or ripped out of the frame. The front bar appears to be missing.

The last thing the investigators want to do now is link this accident to a HS/CHC mechanic error without being 100% sure (120% sure?), as this could tear their community apart.

The Norwegians integrity/professionalism is second to none, so the cause will be revealed...but it'll take time.

[Bishy]

G0ULI, I am an EC225 driver and looking at those pictures and the pattern that the debris landed shows that thing separated very dynamically and i would suggest that a heavy lump of metal hitting a rock from 2000' would smash. This would account for the damage to all the gears we see.
I would be very happy to go flying tomorrow in the 225. I have flown many types and i have never been in a helicopter that can take full fuel and pax. The aircraft is very well designed and I hope that she remains flying.

[henra]

The broken parts of the planetary gear indicate that a failure in the main gear box was most likely to be the initiating event.



Possibly but not necessarily. These epicyclic gears are hardened and if thrown clear, falling free and hitting rock from 2000ft it is easily conceivable that they would break apart



The forward suspension bar mounting looks to have failed under a sudden single stress event although there appears to be some signs of minor cracking or corrosion at surface edges.

Agreed but the cause of this overstress could still be due to various scenarios. Amongst these are still some where first the lower attachment of the bar came lose and then due to it being stuck somewhere while the head tilts backward could shear it off.
Admittedly with the new pieces of information we have a G-REDL scenario seems a bit more probable than other scenarios. Still, we need to wait for the experts doing their work. There is no benefit in jumping to conclusions.

[TOM57]

Just as an ex mechancic, (not aviation) this really looks like a gearbox failure: By the speed of events and extent of damage on the inside components compared to the rotorhead assembly. I believe the problem here is that there is no way to explain how a perfectly running set of gears will instantly go up in pieces. Very scary.

[Bishy]

Tom57, Surely you understand the faster things spin the more centrifugal/centripetal forces they suffer. If something is seriously unbalanced by a failure of a support strut then this could happen. All you have to do is look at what ground resonance can do. A helicopter is naturally unstable and a slight variation can change a lot of things.
https://www.youtube.com/watch?v=0FeXjhUEXlc

[Hot_LZ]

Bishy,

I don't think your take on full fuel fuel pax will have any persuasion when it comes down to getting the 225 back into work on the NS. Yes a capable aircraft but with it's history over the last few years it's going to be a tough one.

LZ

[Bishy]

LZ,
I agree the 225 has got a lot of detractors, for the passengers it is cramped and has a striking similarity to all other super pumas. I think that possibly the PR campaign for the EC225 is lost. This is a great shame because the 225 out performs the S92 in speed and payload let alone cost per NM. The oil companies love the 225 because it is cheaper, but the big question is the future and i fear that this horrific accident that claimed the lives of 13 people (RIP) could be a sad end to the 225. After 16 years since the launch this is the first fatal accident that is pretty good going. there are not many types in the rotary world that can boast that.

[26500lbs]

Bishy,
slight detraction, but how do you come to the calculation that the 225 provides better payload than the S92? Cost per nm, perhaps I dont know, but payload, I am a little unsure. In the operation I was flying in we frequently would have to replace 225 flights with S92 flights due to payload and range, especially when it was poor weather requiring a second onshore alternate.

[Bishy]

26500Lbs,
I have spoken to a few 92 drivers and the 225 has better load and range. A friend who is a 92 driver told me they could only take 16 pax when the 225 could take 19 to the same destination (same weather and wind and bags) the 225 is exceptionally capable.
I hope that answers your question. The cost per NM was a rumour that i heard probably due to leasing agreements.

[AAKEE]

Adding the information from what we saw in the pictures after the accident ( for ex: http://i86.servimg.com/u/f86/11/94/64/62/hub7b10.jpg ) and the pictures from the press conference and preliminary report make me get it hard to get togheter if not something did disconnect without breaking.


There are three strut rods, one did somehowe break, and there is no picture of that one ? ...not found yet..?


The other two is the rear ones, on pictures in the report. One of them seems not connected(rear hand aft ?) to any hinge in the picture of the rotor in my link above...?
The hinge doesnt seem to be broken and the bolt and pin is not connected on the picture in the preliminary report.
How could we explain that one strut rod seems to lack of hinge connector for the helicopter body, but the hinge is not broken, nor is the bolt ?

[26500lbs]

Bishy,
having worked with both machines, that does not reflect my personal experience.

[GKaplan]

Bishy,
having worked with both machines, that does not reflect my personal experience.
I suppose it depends on the dry operating mass of the 92s you used. In our fleet there's approx 500lbs difference between the lightest and the heaviest.
I have to look at the figures but a 'light' S92 might come closer to the available payload a 225 offers.

[GKaplan]

after a look at some data:
our 225s have a DOM (pilots included) of approx 6800kg (average), after full fuel that leaves approx 1920kg for pax.
the 92s weighs around 18370lbs, which after full fuel leaves only 3130lbs/1420kgs

QED ;)


(even the heaviest 225 still offers 100kg more than the lightest 92)

[nl_backseater]

Letmein said:

I'm surprised that there is no picture yet of the bottom bracket area, either showing it intact, or ripped out of the frame. The front bar appears to be missing.


I believe that this is the most puzzling aspect of the AIBN's release of information so far. It is the last detail yet to be revealed that would give creedance to the otherwise confusing service directive and EASB announced by Airbus Helicopters in the week after the crash. But, as letmein also points out, the AIBN will want to be doubly sure before going down that road.

I'm assuming they have the whole of the transmission deck to examine, albeit with extensive deformation, but the forward sus bar anchor point is either there or it's not. If it is still attached the condition should go a long ways to deducing how the forward suspension bar may have departed the airframe, if in fact that bar is missing.

If the anchor is not with the upper deck I guess the whole theory of a slipped pin becomes a very moot point, and a REDL scenario becomes ever more plausible/probable.

I wish the investigation team godspeed in their efforts.

[Pltnorway]

The other two is the rear ones, on pictures in the report. One of them seems not connected(rear hand aft ?) to any hinge in the picture of the rotor in my link above...?
The hinge doesnt seem to be broken and the bolt and pin is not connected on the picture in the preliminary report.
How could we explain that one strut rod seems to lack of hinge connector for the helicopter body, but the hinge is not broken, nor is the bolt ?

This is exactly what I have been wondering all day...

[AW009]

http://www.pprune.org/rotorheads/578298-ec225-crash-near-bergen-norway-33.html#post9373218Sorry, I am still missing statements of the Pro's. Are the MRGB of both types absolute identical? Or which differences are given in detail?
Thank you ahead.

[AAKEE]

Sorry, I am still missing statements of the Pro's. Are the MRGB of both types absolute identical? Or which differences are given in detail?
Thank you ahead.


Nope, not identical but they are quite similar. The L2 was resedigned from earlier Puma variants to be the new generation with some improvements. I don't know if it is exactly the same epicyclic gears.


At least, EC225 has the 30 min run dry feature( glykol cooling/lubricating system) which the AS332L2 dont have(at least I beleave).

[Colibri49]

I've driven EC225s for thousands of hours and there's one difference between this terrible accident and the equally terrible REDL, apart from the fact that the aircraft involved are different variants of the Super Puma family. As far as I can recall REDL had been "making metal" for a few flights or some hours before the epicyclic gears at the top of the gearbox failed. There was communication between engineers and Eurocopter before the accident to establish whether the gearbox should be allowed to continue in service. Please correct me if I'm wrong.


As a consequence and shortly after that tragedy, all Mk2s and all EC225s had the magnets just below the epicyclic stages removed, so that the shedding of metal particles would become obvious much sooner. Is this so please, respected engineers?


What I'd dearly like to know is whether the Norwegian EC225 gearbox had been "making metal" in the run-up to this latest terrible crash, because if wasn't then that inclines me towards believing that a suddenly disconnected suspension strut might well have been the cause.

[Twist & Shout]

Colibri49

While what you say might be true, the complexity of these machines, and the stresses involved can create unexpected outcomes.

Perhaps the making of metal in the REDL case was unrelated to the subsequent catastrophic failure. (A "red herring")
This scenario would make the mitigation applied (to detect metal particles earlier) ineffectual.

Obviously I have no more idea about the cause of this latest tragedy than any other EC225 pilot.
Like everyone involved I hope the actual cause is positively identified. Unfortunately this outcome is far from assured.

There are many potential sources of metal fragments in a transmission. Some more benign than others.

[Nadar]

These epicyclic gears are hardened and if thrown clear, falling free and hitting rock from 2000ft it is easily conceivable that they would break apart

I'm not convinced that is very likely. Hardened steel is brittle but also very strong. It's likely to be much harder than any rock it would hit on impact, meaning that the rock would probably take most of the damage. I don't know what the terminal velocity for such a gear is, but I assume the weight to air resistance factor is relatively low meaning that the terminal velocity will be somewhat limited. In addition AIBN indicated that the corrosion came from the gear parts having spent time in salt water. Although it would be possible for it to land on a rock and bounce into the water, I find if more probable that they landed in the water in the first place. The overview map also indicates that these were found in the sea.


The other two is the rear ones, on pictures in the report. One of them seems not connected(rear hand aft ?) to any hinge in the picture of the rotor in my link above...?
The hinge doesnt seem to be broken and the bolt and pin is not connected on the picture in the preliminary report.
How could we explain that one strut rod seems to lack of hinge connector for the helicopter body, but the hinge is not broken, nor is the bolt ?

The way I interpret the picture of the aft suspension bars is that they (AIBN) have removed the 3 bolts and that that they came down connected to the rotor. My guess is that the 4. bolt is jammed in place by deformations either from when the helicopter came apart or when the parts landed, and that they have left it there to not disturb this deformation if it should need further investigation.

It's still don't know what to make of the bar/rod in the picture or the rotor head, it looks like the lower end of one of them without the mounting/attachement attached. At the same time, the pins can't have been missing since they're all among the found parts and the bolts all seems in one peace. If the bolt and pin is installed there is no way the suspension bar can be detached from the mounting/attachement without any of the parts being broken, so something doesn't add up here. Maybe the mounting/attachement already had been removed on the ground before the picture was taken as this was considered a cruical part to secure?

I'm no expert in this field in any way, but I've always considered the missing pin theory a bit to "easy", and I think they would have a bit more warning signs that 1-2 seconds if that were the case. I've experienced pins breaking and bolts sliding out for the bucket on an excavator some times, and once the bolt lets go of the first "side" you will either break it or it will deform and give you a lot of slack. Since these bolts probably is very hardened, My guess is that the bolt would break before it would move all the way out as long as it had any load on it.

If I'm going to speculate I think the incident two(?) days before the accident deserves more attention. I've read so many articles about this by now so I don't recall what were the exact sources for every bit of information, but unless I'm completely mistaken the incident was described in the press as a "yellow engine warning light" that came on. They then replaced some "engine" part (I never trust journalists to be very precise about such things, so it could be anything), the warning light was still lit and then changed something else and the warning light went away and the aircraft was put back into use. I also read somewhere else that there is some kind of live "analysis" of the HUMS data which lights a "yellow warning light" if something is found to need attention. It's unknown to me whether this system is the "extra safety" system that were installed as a result of the two earlier gearbox failures and removed when the new gearbox was installed or if there's still some live analysis of the HUMS data in corrolation to a yellow warning lamp.

I know that there are loads and loads of warning lamps in there, and that a "yellow light" isn't enought to make any connection as such, but my imagination can't help but think that there could have been a problem triggering some automatic analysis - to which they couldn't figure out the exact cause. If they first replaced one part and tested, and the replaced a second one it indicates to me that they wasn't exactly sure what caused the warning, and the warning could go away even if they didn't fix the underlying problem (for example because they could have "treated a symptom" instead of the root cause).

I'm not saying it's something here, I just think it's strange that with all this speculation I've seen nothing about this possible connection.

[TylerMonkey]

So let me understand what I'm seeing in the photos. The front strut rod somehow was fractured at the top end as per photo and therefore most likely was no longer attached to the rotor head when it landed.
The head landed with only the two rear strut rods still attached ? On their lower ends were the hard point mount plates that were ripped away from the fuselage, (bolt holes, missing bolts). The 4 connector pins and their nappy pins (not all nappies but at least one per end) landed still installed in the two rear strut rods.
Why can we see a connector rod in the head pic on the rocks ( I highlighted with the red arrow ) sticking up in the air with no connection, no pin, no nappies. Should not this Rod be one of the two rear rods? If so this end would have a pin and mount plate attached if it is the lower point. If it is the upper connection point it should still be pinned to the rotor head.

[AW009]

Berlin/Oslo (dpa) - Der Absturz eines Eurocopter-Hubschraubers an der Küste Norwegens hat nach Angaben der deutschen Luftwaffe keine Auswirkungen auf die Flugbereitschaft der Bundeswehr. «Das in Norwegen eingesetzte Modell H-225 Super Puma - auch Eurocopter EC 225 - haben wir nicht im Bestand», sagte ein Luftwaffensprecher am Samstag [30. April 2016] der Deutschen Presse-Agentur in Berlin. «Es ergeben sich daher keine Konsequenzen, irgendwelche Überprüfungen an unseren Helikoptern [Cougar AS-532-L2] durchzuführen oder gar den Flugbetrieb mit Hubschraubern der Flugbereitschaft einzustellen.»

Translation: Berlin / Oslo (dpa) - According to the German Air Force, the crash of a Eurocopter helicopter on the coast of Norway, does not affect the Special Air Mission Wing of the German Ministry of Defence (BMVg) to the Bundeswehr (German armed forces). «The Model H-225 Super Puma - Eurocopter EC 225 operated in Norway we do not have in stock,» an Air Force spokesman said on Saturday [30th of April, 2016] to the German Press Agency in Berlin. «Therefore no consequences are resulting to execute any savety inspections on our helicopters or even suspending flight operations with helicopters [Cougar AS-532-L2] of the the Special Air Mission [and VIP-] Wing of the German Ministry of Defence to the Bundeswehr»

…. paper pusher!:ugh:

When in doubt the older MRGB-Layout of AS 332-L2 / Cougar As 532-L2 is more prone to mashing of epicyclic gears as the newer MRGB of H 225 / H 725 Caracal, does this mean, that the Air Force spokesman of Special Air Mission [and VIP-] Wing of the German Ministry of Defence to the Bundeswehr told on Saturday [30th of April, 2016] “bull****” to the German Press Agency in Berlin!? To say it in principle, this paper pusher wanted to be foxiest already one day after the crash and thirteen days before the Norwegian and British authorities haven't released the ban of H225, but have actually extended the ban to the AS 332L2?:*

[birmingham]

I think the pictures chosen by the AIBN simply contain items that they are examining - no more than that;

There was an amber warning in the days before the crash - that would have to be looked at as part of any investigation methodology.

They have a destroyed gear - that would have to be explained.

They have an incomplete suspension bar assembly so they need to try and find the rest of it and make sense of the wreckage.

However, they are clearly not at a position where they feel they understand the causes of the accident sufficiently to (a) Make a more specific statement (b) relax the ban on commercial flights.

While they would obviously continue to search for missing components in any case, their emphasis on this seems to suggest that lack of specific items is directly hampering their ability to properly understand the principal initiating cause - or more likely provide enough evidence to make a definitive statement.

[Colibri49]

Twist & Shout



"There are many potential sources of metal fragments in a transmission."


What you say is undoubtedly true, however in the case of REDL before it crashed, the particles of metal were detected and identified as coming from the top of the gearbox i.e. the epicyclic reduction stages. Or so I believe.


Again I ask our engineers "Was there any history of the Norwegian EC225 gearbox making metal before the crash, because if not the likelihood of similarity with REDL is probably reduced?"

[epkp]

I may be wrong but I am astonished to see that nobody noticed that the suspension bars were secured with only one safety pin.
Normal configuration: each extremity of the suspension bar should be secured with two safety pins strapped each other.
Why it is not the case?

[AW009]

See January | 2012 | Isambard's Lad (http://isambardkingdom.com/?m=201201)! Would be a freewheeling unit between MR and MRGB opportune? Is it realizeable?

[Torcher]

To keep it real.

In my world, when you add the factor of required climb gradients OEI, the 225 does not in any way outperform the S-92 in the range/payload department.

On a standard day, an S-92 can do a 5% Climb (Standard Copter SID) OEI, at Max gross weight (26500 lbs), up to normal cruise altitudes.

Try that on a 225 (5% OEI Climb), and you will find that you will have a significantly reduced take off weight, as in less range/payload

And that makes the real life payload/range better on the S-92, as verified by the observations of member 26500lbs

Torcher

[birmingham]

May 13, 2016

"Airbus Helicopters welcomes the AIBN’s preliminary report and is encouraged by the progress of the investigation. We continue to focus our efforts on providing assistance to the investigation team, while working closely with our global customers to ensure that checks mandated by Airbus Helicopters and EASA are completed in support of the continued operations of the EC225LP."

By inference AH continue to maintain that the aircraft is safe to fly and the actions of UK & Norway authorities are unnecessary. They don't even mention the extension of the ban to earlier models. One can only assume they wouldn't be so reckless unless they are aware of key facts not yet in the public domain.

[spectral]

Nope, not identical but they are quite similar. The L2 was resedigned from earlier Puma variants to be the new generation with some improvements. I don't know if it is exactly the same epicyclic gears.


At least, EC225 has the 30 min run dry feature( glykol cooling/lubricating system) which the AS332L2 dont have(at least I beleave).
Just the body is the same all the part inside was different the material is different...

And is true for dry run but in reality it's more than 30min the records it's 48min without oil and without glycol...

[spectral]

To keep it real.

In my world, when you add the factor of required climb gradients OEI, the 225 does not in any way outperform the S-92 in the range/payload department.

On a standard day, an S-92 can do a 5% Climb (Standard Copter SID) OEI, at Max gross weight (26500 lbs), up to normal cruise altitudes.

Try that on a 225 (5% OEI Climb), and you will find that you will have a significantly reduced take off weight, as in less range/payload

And that makes the real life payload/range better on the S-92, as verified by the observations of member 26500lbs

Torcher
"OEI" it's not "one engine INOPERATIVE"

[whenever]

Both 225s and 92s work to Class 1 and on any given day the 225 always has a better payload available on the NS. The 92 is also more expensive and has a poor serviceability record with parts supply very poor compared to AH. People seem to have a short memory and up to the point of this tragic accident the S92 was all but reduntent on the NS. Most new contracts have either been for 225s or a mixture of 225s and 92s with the ratio being in favour of 255s, the reason......cost, serviceability and endurance.

I also hear complaints of back pains and hearing issues from 92 pilots and passengers complain about vibration and having to sit side by side feeling cramped where as on the Puma the slightly offset seating and better leg room being an advantage although still tight.

For all who say the Super Puma should be retired, then what's your plans should a S92 have an accident in the next few years? Personally I hope that it's not the end of the 225 but emotions are running high. This is the first fatal accident with the 225 on the NS. The ditchings were controlled landings with warnings, drills, floats and rescue all working flawlessly. The issue was found and resolved.

The offshore world is dangerous by its very nature and although huge amount of money is spent to mitigate risks as much as is possible it is pie it the sky thinking to expect a completely risk free environment. That includes the transport system. Hence the workforce are rewarded in part for the higher risks in well above average wages.

I would fly the Super Puma again but as time goes on I expect to be on a conversion course over the next few months as the industry reacts to the situation. What ever the cause of the crash I just hope it won't take too long to find and divulge.

[Uneasy Rider]

Following on from Colibri49's posts further up the page, I quizzed the guys in Norway about the REDL incident when I did my L2 type rating. I was told the root cause of the accident was the break up of the 'critical mast bearing'. The guy actually went and got one from the stores to show us what it looked like.

[megan]

"OEI" it's not "one engine INOPERATIVE" The FAA define OEI as meaning one engine inoperative.

What is your definition spectral?

[roundwego]

Megan, I think he may mean that SID gradients are based on all engines operating. As far as I am aware, there is no requirement to maintain 5% gradient in the event of a power unit failure as long as safe terrain seperation is maintained which may require a turn off the SID as part of a contingency procedure.

[212man]

Megan, I think he may mean that SID gradients are based on all engines operating. As far as I am aware, there is no requirement to maintain 5% gradient in the event of a power unit failure as long as safe terrain seperation is maintained which may require a turn off the SID as part of a contingency procedure.

That's what I thought he meant too, although a standard SID is 3.3% and - as you infer - most airlines develope engine out SIDs because they, too, are often unable to comply following an engine failure.

[keithl]

That's what I thought he meant too, although a standard SID is 3.3% and - as you infer - most airlines develope engine out SIDs because they, too, are often unable to comply following an engine failure.

Well, torcher does refer to "Standard Copter SID" of 5%, which IIRC is right for Cat H.
I, too was confused by spectral's "OEI it's not one engine INOPERATIVE", but now take it to mean "a SID is not an OEI procedure". Clarity of communication - a CRM skill...

[Fareastdriver]

If you lose an engine during a SID you aren't taking any payload anywhere.

[roundwego]

If you lose an engine during a SID you aren't taking any payload anywhere.
Well hopefully still upwards to MSA and back to land at departure point or onwards to T/O alternate in the event departure point not suitable for landing.

[AAKEE]

I guess there is other places to discuss OEI, SID's and S92 vs EC225 ?

[Satcomm]

I guess there is other places to discuss OEI, SID's and S92 vs EC225 ?

Well said AAKEE! Regardless of what aircraft can do what, the 225 will fly again! There was a reason it was selected for each contract that it is on. There aren't enough spare S92s in the world (even during the downturn) to replace all the 225/L2s out there.

[n305fa]

Following on from Colibri49's posts further up the page, I quizzed the guys in Norway about the REDL incident when I did my L2 type rating. I was told the root cause of the accident was the break up of the 'critical mast bearing'. The guy actually went and got one from the stores to show us what it looked like.
Just for clarity.

The REDL accident was due to the failure or a 2nd stage epicyclic planet gear, not a "critical mast bearing". The gear broke up and one piece was dragged between the epi case/ring gear and the remaining gears which burst the case. Case failure caused the rotor torque to be transmitted through the lift struts which then failed.

The 225 and the 332L2 have a large amount of MGB commonality. The 225 main module is the same configuration as the 332L2 with some material / coating changes to various gear wheels. The epicyclic module on the 225 is common to the 332L2. The 332L2s conical housing is replaced by the 225s flared housing with the emergency lube system.

[TylerMonkey]

I may be wrong but I am astonished to see that nobody noticed that the suspension bars were secured with only one safety pin.
Normal configuration: each extremity of the suspension bar should be secured with two safety pins strapped each other.
Why it is not the case?

I can only see 2 possibilities.

1. This is how the rods were found after the event involving big dynamic forces.
All 5 connector pins that were recovered had one nappy pin remaining in each.

2. They found more nappy pins but only displayed 5 ( unlikely IMO but possible )

Any other ideas ?
.

[Twist & Shout]

The REDL accident was due to the failure or a 2nd stage epicyclic planet gear, not a "critical mast bearing". The gear broke up and one piece was dragged between the epi case/ring gear and the remaining gears which burst the case. Case failure caused the rotor torque to be transmitted through the lift struts which then failed.

And what, if anything, was done to reduce the chances of this happening again?

Perhaps this has happened again.


If it has.
Regardless of statistical evidence of reliability, having a rotor system depart the airframe "every so often" is going to prove unacceptable, to many.

[n305fa]

And what, if anything, was done to reduce the chances of this happening again?

Perhaps this has happened again.


If it has.
Regardless of statistical evidence of reliability, having a rotor system depart the airframe "every so often" is going to prove unacceptable, to many.


Reading the report the AAIB made 17 recommendations for improvements, mostly around improving MGB condition monitoring and MGB design. I'm not sure how many were accepted by the regulators and AH though.

[Colibri49]

n305fa


Thanks for the clarification of what caused REDL's gearbox to fail. That accident didn't just happen with no prior indication. Metal particles from the epicyclics were detected in the period of flying hours and/or days before it happened.


Hence my question "Was there any history of the Norwegian EC225 gearbox making metal before the crash, because if not the likelihood of similarity with REDL is probably reduced?"

[n305fa]

n305fa


Thanks for the clarification of what caused REDL's gearbox to fail. That accident didn't just happen with no prior indication. Metal particles from the epicyclics were detected in the period of flying hours and/or days before it happened.


Hence my question "Was there any history of the Norwegian EC225 gearbox making metal before the crash, because if not the likelihood of similarity with REDL is probably reduced?"

Colibri49

I don't disagree.
There were issues with the actions taken after the chip was found on REDL but no further chips were detected in the week of operation prior to the accident. We will never know if REDLs MGB would have been declared US if the full checks had been carried out but reading the report the lack of further chip detections before the last flight was unusual. The monitoring systems are designed to detect progressive not rapid failure modes so there may have been no indication that the 225's MGB was in distress.

[Colibri49]

The lack of further chips might be explained by the design of the gearbox, which up until that time had a series of powerful magnets mounted on a shallow conical tray just beneath the epicyclics. Almost immediately thereafter the factory ordered all such magnets removed and I saw with my own eyes when this was done.


What were those magnets for? Possibly to catch the bulk of metal particles thereby preventing damage to components lower down the gearbox. I guess the philosophy was that at least one or two particles would pass through the ring of magnets and reach a detector lower down, giving enough warning of an impending problem at the top of the gearbox. This actually happened and yet the factory somehow allowed REDL to continue flying.


The reason for the haste with which those magnets were removed (the original Mk1 Super Puma didn't have them) has never been explained well enough for my liking.

[n305fa]

The lack of further chips might be explained by the design of the gearbox, which up until that time had a series of powerful magnets mounted on a shallow conical tray just beneath the epicyclics. Almost immediately thereafter the factory ordered all such magnets removed and I saw with my own eyes when this was done.


What were those magnets for? Possibly to catch the bulk of metal particles thereby preventing damage to components lower down the gearbox. I guess the philosophy was that at least one or two particles would pass through the ring of magnets and reach a detector lower down, giving enough warning of an impending problem at the top of the gearbox. This actually happened and yet the factory somehow allowed REDL to continue flying.


The reason for the haste with which those magnets were removed (the original Mk1 Super Puma didn't have them) has never been explained well enough for my liking.

According the the REDL report the ring of magnets was put in to protect the lower part of the gearbox, as you though, from particles released in the epi and mast areas to try to make a modular MGB. The problem was that the epi chip detector is not very efficient, small size, big epicyclic case radius, so in the event that a chip was found on the epi plug you had to inspect the ring of magnets which probably hoovered up the majority of chips coming from high up in the MGB.

The reason they removed the ring of magnets is that they effectively masked the master chip detector. Removing them increased the probability of detecting chips as all of the oil goes into the sump and the MGB chip detector is in a low spot in the sump, near to the oil scavenge line. On the 332 it would also trigger the chip warning in the cockpit, which doesn't happen for an epicyclic chip detection, that only triggers on HUMS

[birmingham]

On the G-REDL accident the failure occured in the second stage planetary gear and there was significant evidence of both fatigue cracks and that the unit had been in contact with metal particles in the days before the crash. In this one the AIBN says that detailed analysis has not yet taken place but that initial inspections didn't reveal any evidence of fatigue. That may (or may not) suggest a different failure mode this time but it will be necessary to await detailed analysis - they may also need some of the missing parts of the gear to be definitive.

[birmingham]

and also from the earlier report ...

"The gearbox, (serial number M2092) had remained attached to the airframe by
the flexible mounting plate, which is designed to react the gearbox torque. The
mounting plate had sustained little damage in the accident. This observation
was pertinent in that it helped to exclude the possibility of a lift strut failure as
being a primary cause of the accident, since such an event would transfer lift
loads, via the gearbox, into the mounting plate causing obvious distortion"

[n305fa]

On the G-REDL accident the failure occured in the second stage planetary gear and there was significant evidence of both fatigue cracks and that the unit had been in contact with metal particles in the days before the crash. In this one the AIBN says that detailed analysis has not yet taken place but that initial inspections didn't reveal any evidence of fatigue. That may (or may not) suggest a different failure mode this time but it will be necessary to await detailed analysis - they may also need some of the missing parts of the gear to be definitive.

The other issue with the AIBN investigation is the lack of material from the epicyclic that has been recovered, so at this stage they wouldn't be able to confirm too much. With REDL the AAIB recovered all of the stage one gears, 7 complete stage 2 gears still attached to the planet carrier and 75% of the failed gear, even then the evidence of fatigue was limited to part of one fracture face on a single piece of the failed gear.

[Colibri49]

n305fa


According to what I've researched on Google, there is a dedicated "epicyclic module chip detector" which you describe above as "not very efficient, small size, big epicyclic case radius" which is generally correct. What I myself saw when the conical housing and top of the gearbox got dismantled to remove the ring of magnets, was a lip right around the edge of the tray to which the magnets were attached.


There was a gap of 1 or 2 cm in this lip to allow oil draining down from the epicyclics to get "focused" into a narrow stream passing over the epi chip detector below the gap (engineers please correct me if I'm wrong), thereby increasing the chances of metal particles getting detected.


So if that lip with a gap is still part of the tray's design and now that the ring of magnets is no longer in place, even the slightest particle from the epicyclics and mast area would be detected at a very early stage and long before the risk of a catastrophic break-up might occur. I can't accept the idea of only one or two particles being detected by this improved system (without magnets) followed by a sudden break-up?


Hence my question for the 3rd time "Was there any history of the Norwegian EC225 gearbox making metal before the crash, because if not the likelihood of similarity with REDL is probably reduced?"

[industry insider]

Colibri

Hence my question for the 3rd time "Was there any history of the Norwegian EC225 gearbox making metal before the crash, because if not the likelihood of similarity with REDL is probably reduced?"

There is an investigation into a catastrophic failure of some kind which killed 13 people being conducted by the AIBN.

There are potentially multiple liability issues, the future of a whole Airbus Helicopter product line is at stake, probably some helicopter operators and part of a global industry.

You can ask as many times as you like but I don't think you are going to find that answer on here anytime soon, probably until the report is issued.