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EC225 crash near Bergen, Norway April 2016

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EC225 crash near Bergen, Norway April 2016

Old 20th May 2016, 04:53
  #821 (permalink)  
 
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@casper64: ’nomen est omen’ or ’ si tacuisses, philosophus mansisses’.
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Old 20th May 2016, 05:53
  #822 (permalink)  
 
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There is a better illustration of the structure here EC225 Main Rotor Head and Main Gear Box Design

The gears don't look like G-REDL, the separation is not the same as G-REDL, but the top of the front suspension bar has failed, whereas the rear two appear to have been pulled out at the bottom.
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Old 20th May 2016, 08:11
  #823 (permalink)  
 
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Thankyou for the link squib66. The question is, did the front suspension top end fail as part of the initial incident or was it still attached and subsequently failed when the MRH hit the ground? If it was the former, what caused it to become separated from the main wreckage? And if it was the latter, where is the bar now? (I presume they would have included it in their pictures if they had it.)
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Old 20th May 2016, 09:16
  #824 (permalink)  
 
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Mitchaa

n the initial report released last week for OJF , you can see a split planet gear in the pictures with a lot of that particular gear I presume still unrecovered? I don't think there's enough there to rule out epicyclic failure and lean towards suspension bar failure personally.
Kawijet

It makes sense - the gearcasing fractured at the point of the upper 2nd stage epicyclic module and thats where the gearbox parted with the MGB. Above this is the conical. So if the conical also parted the upper gear carrier would have fallen free of the rotorhead leaving the splined connector but that is not what you see in that photograph of the recovered rotorhead. It does not taper from the swashplate down to the splined rotor mast like in this instance, but looks the same width right down, due to the conical and upper module still in position.... Does that make sense?
I understand the failure mode of REDL and the consequent fracture and separation.
However, if there was an epicyclic failure of some kind with OJF, it may not be exactly the same failure mode, the separation may not therefore be identical to REDL?
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Old 20th May 2016, 11:07
  #825 (permalink)  
 
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BASys,

Not really sure what you are on about to be honest. Look at the 2 semi circular abrasions on the red and black paint - I said nothing about it being on a different airframe and different colours? What else on a helicopter can cause large radius semi circular abrasion marks other than the rotor?
As for position of the rotor head - you are aware the rotor head completely detached itself from the airframe? So you tell me what position the rotor head was in? Anything is possible as we are not talking about normal running conditions. Look at the blades - they obviously struck the helicopter so its not impossible it grazed the panel as it departed the airframe is it? Not so supernatural or a rediculous thing to suggest....

Mitchaa,

Skotty was spot on with his diagram. Epicylcic gear failure leaves NO room in the gearbox for broken parts and so the gearbox casing gets burst open at the epicyclic ring where the debris gets jammed between planetary gears and the ring gear. It wouldn't burst off the conical housing as that is above the epicyclic. Once the gearcase has fractured open then any rotor torque on the conical housing would be practically 0 as the fractured section is free to rotate seperate from the MGB. Therefor it would not shear here. For this reason I believe the failure WOULD be similar to G-REDL if it was an epicyclic destruction. At least the conical housing remaining. That is not the case here.

It is not easy to see on the G-REDL recovery picture but if you zoom in you can see the edges of the 2 epicyclic gears. I have tried to highlight them for you.

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Old 20th May 2016, 16:29
  #826 (permalink)  
 
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In the case of G-REDL the failed gear was propelled like a knife through the casing. That hasn't happened here it seems (the AIB had the epicylic casing in the shed in Bergen).

If the MGB seized totally either the shaft would surely fail in torsion or the splines would be torn off. There is no sign of that or of the tail drive shaft flailing after a sudden stoppage. If there damage like that it is difficult to imagine the AIB would not have said.

Does that mean we can conclude what happened?

No.

Only a fool would try to draw conclusions publicaly on cause second hand.

However I can see how a possible suspension bar attachment failure is worth an AD especially as one servo (the front one) separated and most of the front suspension bar is missing.

Does anyone know if any problems have been found in the rest of the fleet following the AD?

And what news of Shell Norway's action against CHC?
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Old 20th May 2016, 18:50
  #827 (permalink)  
 
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3 Suspension bar

My profession is mechanic, more then 30 years with the steel technique, but I can not conclude the cause of the accident on Turøy.
I hope AIBN.no find the cause. I will explain elements called : Problem number 1

A
Fracture surface on the bearingarm tell me that the steel structures is hardened, and the steel toughness is small.
Steel structure change during welding, and the break may have occurred as a result. I do not know if annealing is done.
Ref : Weld is somtime stronger, and the ship Sleipner broke in 2, near the weldplace
It is best to make all suspension bar in one piece. Another factor is whether all suspension bar are vibration and bendtestet
by the manufacturer. Normal procedure by roller bearing assembly is to heat the bearingarm in oil and then assemble the bearing
Normal clearance is some hundredths mm clearance. When bearingarm has cooled then the roller bearing sits completely fixed.

B-C
Probably when the bolt C is mounted into B it will be few hundredths mm clearance, and the result becomes slack. Is there any
slack - vibration damage by E. I guess all the parts are not heated before bolt C is fitted into B. Before the put the bolt to travel block on a drilling rig
the boltis being frozen before assembly. Injuries outside B ?
If shaft C is loose and rotates - vibrates will D change shape. Shown in the picture F.
The locking string has changed shape. This can wriggle out of the shaft or be cut. A missing / broken shaft / part / may result in helicopter crash.
There are many other and better technical solutions then the pictures shown.
AIBN.no present images shown 3 suspension bar and 5 bolts
Attached Images
File Type: png
2016-05-20.png (600.7 KB, 104 views)
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Old 20th May 2016, 19:25
  #828 (permalink)  
 
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@Mitchaa: If you are meaning https://www.google.de/search?q=Torqu...HSErAlYQsAQIHg your satiric humour despite all tragedy is mind-blowing!

Last edited by AW009; 20th May 2016 at 19:34. Reason: my poor english
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Old 20th May 2016, 19:25
  #829 (permalink)  
 
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The upper planet shown has three fracture surfaces, all exactly spaced. Note the heavily smeared inner diameter on the left but absent on the opposite side of the fracture. This indicates roller rotation against a separated raceway. On the question of time, uncertain, but such conditions take more than a few seconds to develop. I would be interested in seeing the fracture propagation direction. If the planet were "squeezed " then fracture starts at ID at two places 180 degrees apart and OD opposite. The lower pictured pinion has one visible fracture likely starting at ID. If all fracture started at ID then it may be a gear vibratory resonance to get uniform 90 degrees away. Otherwise that's odd coincidence.
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Old 20th May 2016, 19:36
  #830 (permalink)  
 
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Originally Posted by Mitchaa View Post
Never Fretter,

Explain why the first and 2nd stage gear wheels are found on the opposite ends of the island without a gearbox rupture?

Rumour has it that there's been quite a few loss of torque cases found on the MGB BBQ mounts from various operators around the world. One big red herring in my opinion.
I don't HAVE to explain anything and am rather disinclined as you have your heart set on your pet theory.

But IF the 'top' was pulled of the MGB and the MR had exerted a rearward load until the rear suspension bar attachments failed then it would not be totally surpising to see some gears released.

The island you mention is tiny. You are over imaging the significance of a limited set of debris data!

The AD is not on the barbeque plate attachments. Go look at squib's link as you really need to understand the layout if you are going to persist with pushing your single theory continuously.
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Old 20th May 2016, 19:58
  #831 (permalink)  
 
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I believe there maybe another statement/report from the AIBN next Wednesday.
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Old 20th May 2016, 20:51
  #832 (permalink)  
 
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"Rumour has it that there's been quite a few loss of torque cases found on the MGB BBQ mounts from various operators around the world. One big red herring in my opinion."

If you were logging with the machine or working in a high airframe cycle, (+20 cycles / hour) enviornment, then, yes.

IFR a/c, extremely unlikely.

While logging in CH in the mid '80's we had to implement a 25 hr tq check on the 36 mgbx/bbq plate bolts. The "new" AS/AH bbq plate to fuselage hardware is a 50 hour tq check.
This was based on our experience as well as info on Columbia Helicopters earlier logging experience with the AS332C.

Something that has been bothering me since the a/c went down with no warning. The rotor / epicy / mgbx moduls had been seperated and reassembled in the week (+/-) prior to the final flight?
Was the reassemble of all these components done outside of the airframe and on a 5 degree plate and then as a complete unit installed on the a/c?
Or was mrh assembly replaced on the a/c?
The question that is open for me, did the maintenance engineers use the 5 degree position on the mrh lifting jig to install the mrh/mast in the epicyclic upper case?
There was rumour running around in '83-'84 that in the Gulf of Alaska an AS332 landed on a deep water rig and had a bang during shut down. The epicyclic was damaged. The complete transmission assembly was replaced before the return flight. The fault was traced back to a mrh installation without the 5 degree setting on the mrh lifting jig.
Again, this was a rumour that was circulating at the time.

It is a fact that the epicyclic upper gears do not take kindly to rocking the mast into place without have the lifting jig positioned correctly.

I hope for sake of the engineers that last worked on this a/c that this is not the case.
Marcus
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Old 20th May 2016, 21:20
  #833 (permalink)  
 
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The only theory I have is that Mitchaa has made up his mind and will ignore any possibility that doesn't match his own. He has and may continue to provide supporting evidence and quiet frankly amusement

New evidence from the AIB may well point to one of several possibilities but selective interpretation will only point to self-deception.
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Old 20th May 2016, 21:22
  #834 (permalink)  
 
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Mitchaa,

The gearbox may well have ruptured. Lets just say If the suspension bar failed and caused the rotor to pitch forwards, the stresses imposed on the gearbox would have fractured the gearbox housing for sure. Even when the conical housing failed the remaining suspension bars would have kept the rotor mast splines in engagement for a short time before the struts finally failed releasing the rotor head. During this time the engines would be preventing the gearbox from pitching forwards and the side load on the epicyclic module would be extremely high. It is entirely possible that the epicyclic module casing could have been a secondary failure releasing parts. The primary cause however would be suspension bar failure.

I am still of the opinion that because of the absence of the Conical housing this is a Suspension Bar failure. AH must be sure its not an epicyclic failure also before making such a bold statement as they have done as it is pretty much Reputational suicide if they are wrong! Thats what makes me believe that maybe they are right in this instance. Its not the same failure as G-REDL in my humble opinion..... for all that is worth.

I am eager to hear what the crash report says on this one.
Time will tell.
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Old 20th May 2016, 22:23
  #835 (permalink)  
 
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I don't understand why so many people think AH has made a bold statement. This is not a repeat of anything that has ever happened to the 225. They know it,their lawyers know it and any one in the industry SHOULD know it. IMO, they went to the crash site, looked at the gearbox and hums, easily determined this is not a repeat of the previous 225 failures and issued the statement. From initial scene investigation, probably noted the suspension bars detached (whether failed or ripped from the aircraft) and started by getting all operators to inspect the installation, then report findings.

As for the L2 incident, yes, this is most likely the same type of failure. Again, just my opinion. I've seen pics from 2 rolled over Pumas .... Beat the blades clean off of both machines .... No MGB failure. No housing failure. I think if a suspension bar failed the gearbox would eventually roll right out of the aircraft with the head still attached. The other thing nobody has mentioned is the fact that much like REDL, most of the dampers are let go .... Most likely from the MGB sudden stoppage. The fact that the suspension bar fittings are damaged or broken off is meaningless at this point. They are not meant to take the forces of the MGB failure.

This of course is just my opinion and is meaningless as well!!

Last edited by Satcomm; 20th May 2016 at 22:50.
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Old 21st May 2016, 08:12
  #836 (permalink)  
 
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Satcomm,

I part agree with what you say but then you kind of go on to contradict yourself.
The AH tech experts that travelled to the crash site must have found some evidence to suggest that this is NOT the same as previous gearbox failures (As in G-REDL's epicyclic failure) as they went from: "we are allied with the decision taken to put all commercial EC225LP passenger flights on hold. " and 48 hours later to "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."

So I agree they found something but it is a pretty bold statement to suggest their helicopters ARE safe to fly just a few days after a catastrophic crash as the investigation has barely begun let alone concluded! Thats bold! Unless they are absolutely SURE this is NOT the same as G-REDL in any respect.

But you contradict yourself for the very point I have made above. You say this is most likely the same cause as the L2 (G-REDL) but thats what is so strange about this AH statement. If it was the same failure they would need details of the planetary gear metallurgy inspection report, and the conclusions of the accident report, to make damn sure it wasn't a failure due to a manufacturing defect, for which, they would be directly responsible! So they have to be sure for whatever reason this is not an epicyclic episode again especially at this early stage.

Its because of this, and the differences in the rotorhead seperation, I am inclined to agree with them....

...However, I do agree with you completely on Opinions.... and that one above is only mine. For all that is worth.
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Old 21st May 2016, 12:09
  #837 (permalink)  
 
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Kawijet, REDL was an AS332L2 not a H225. My point is, legally this is NOT a repeat of anything that has ever happened to the H225.

For the statement time lines. AH made its initial statement about being allied while their expert team was on route to Norway. Given the fact that there is a history with the lower section of the 225 (and 225 only) MGB, this was probably a wise thing to do. 48 hours later, travel time and wreckage recovery, they must have seen something to be certain that it was not a repeat of again the above MGB issue. This is when they issued the so called bold statement of it being safe for flight. I believe they also stated at or around this time that this was not a repeat of the issue that cause the "2012 ditchings". No mention of the possibility of it being a similar issue of the 2009 AS332L2 Epi failure.

I do agree that I have made at least one incorrect statement in my last post. When I said this was a "repeat" of REDL. A repeat would be the same type of aircraft with the same part number main gearbox. Neither of which are the case. Again, this will NOT be a repeat of anything that ever happen to the 225.

As someone else mentioned earlier after the AirEgypt crash, is Airbus now suppose to ground the entire fleet worldwide of every A3XX series of aircraft because there was an unexplained accident. How many of the people going off shore today on a S92 got to their heliport via an A3xx series of aircraft and never questioned that.

Last edited by Satcomm; 21st May 2016 at 12:22.
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Old 21st May 2016, 16:01
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For me the core issue is not „had it been a repetition of G-REDL“, because it wasn’t. By a view on the future and the fate of SUPER PUMA, the essential question is, „might the catastrophe of LN-OJF (H225) and a repetition be possible also by an AS 332 L1/L2“?

Last edited by AW009; 21st May 2016 at 16:12.
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Old 21st May 2016, 16:10
  #839 (permalink)  
 
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16 Dec 1980 - SA330J - 9M-SSC - Main rotor separated after A second stage epicyclic module planetary gear fatigue failure- on contract to Sarawak Shell.
01 April 2009 - AS332L2 - G-REDL - Same as above.
29 April 2016 - EC225 - LN-OJF - Main rotor separated ...

Does it matter what the reason is? Seems to be not confined to the 225 / L1 / 330.

If this case was due to a different reason, how much confidence does that instill, how many reasons can there be for the main rotor to separate from the Puma with it's grandfather rights gearbox?
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Old 21st May 2016, 16:44
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@aheoe26104: Sorry; I’m allowed to impute to you that you have never been a member of an investigation board. You are making prejudicial comments and you haven’t understood or even haven’t read the representational thread?
The case 'LN-OJF' is too serious and the dignity of the fatilities is too invioable to be discounted by hollow and unprofessional comments instead of substantial arguments and facts!

Last edited by AW009; 21st May 2016 at 17:05.
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