EC225 crash near Bergen, Norway April 2016
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cteneto139 you are quite right ... and your opinion is based on a much deeper knowledge of the machine and the risks than most AH customers.
I think the regulators may have done AH a favour here. A business as usual until we understand the problem worked out ok the first time we has a catastrophic failure. it would also have worked if the last incident was in the distant past. It will still work away from the NS where customers were not so directly affected by previous incidents. But in the NS customers and trade unions would have been in an impossible position. Rightly or wrongly a substantial number of them had formed the opinion it was a dangerous type - a view that could only be dispelled by a decent interval of accident free flying. AH can tell that constituency the thing is safe, problem is many are no longer listening.
AH are in a terrible position; If they genuinely believe that the accident was caused by other factors than the gearbox (and surely they must) then all they can really say is that there is no reason to stop flying it. They can't give vent to their full suspicions for a whole variety of reasons many of them to do with liability. If they don't have private evidence to support this (surely they must)they are heading for a Gerald Ratner moment.
and what about the report it can have four very general conclusions these being;
A. It was a repeat of REDL - everybody hopes not, Airbus clearly believes that wont happen - result catastrophic for Pumas everywhere
B. It was caused by some other form of deign or manufacturing failure result almost as bad as A above
C. It was caused solely by a maintenance error. Result people will want to know how such a thing could have happened in the NS and why it would not happen again.
D. No conclusive reason could be given (see A above)
None of the above scenarios make for good reading. At least if the AIBN can ultimately make an evidenced based conclusion as to the cause AH and its operators can start to move forward.
There is a new model scheduled for 2022 - not far ahead.
I wonder how many Pumas will be flying in the North Sea when it shows up?
I think the regulators may have done AH a favour here. A business as usual until we understand the problem worked out ok the first time we has a catastrophic failure. it would also have worked if the last incident was in the distant past. It will still work away from the NS where customers were not so directly affected by previous incidents. But in the NS customers and trade unions would have been in an impossible position. Rightly or wrongly a substantial number of them had formed the opinion it was a dangerous type - a view that could only be dispelled by a decent interval of accident free flying. AH can tell that constituency the thing is safe, problem is many are no longer listening.
AH are in a terrible position; If they genuinely believe that the accident was caused by other factors than the gearbox (and surely they must) then all they can really say is that there is no reason to stop flying it. They can't give vent to their full suspicions for a whole variety of reasons many of them to do with liability. If they don't have private evidence to support this (surely they must)they are heading for a Gerald Ratner moment.
and what about the report it can have four very general conclusions these being;
A. It was a repeat of REDL - everybody hopes not, Airbus clearly believes that wont happen - result catastrophic for Pumas everywhere
B. It was caused by some other form of deign or manufacturing failure result almost as bad as A above
C. It was caused solely by a maintenance error. Result people will want to know how such a thing could have happened in the NS and why it would not happen again.
D. No conclusive reason could be given (see A above)
None of the above scenarios make for good reading. At least if the AIBN can ultimately make an evidenced based conclusion as to the cause AH and its operators can start to move forward.
There is a new model scheduled for 2022 - not far ahead.
I wonder how many Pumas will be flying in the North Sea when it shows up?
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Accident to Aerospatiale SA330J, 9M-SSC, 16 December1980
In REDL's accident report you will also find reference to this:
1.18.4 Accident to Aerospatiale SA330J, 9M-SSC, 16 December1980
On 16 December 1980, an Aerospatiale SA330J Puma helicopter, 9M-SSC, crashed in a swamp forest near Kuala Belait in the State of Brunei. The crew of two and all 10 passengers were fatally injured in the accident, which resulted from an MGB failure similar to that which occurred on G‑REDL. The MGB of the SA330J is fundamentally similar in layout to those of the AS332 series of helicopters, although the components are not interchangeable and the gear material specifications are different. The gearbox in the 9M-SSC accident had a recent history of quantities of metallic debris being found on the magnetic chip detector in the main module. The epicyclic module was not equipped with a detector.
The synopsis of the report on this accident contained the following:
‘The accident occurred following the loss of the main rotor assembly, together with the attached bell housing containing the second stage gears of the epicyclic gearbox. Almost simultaneously, the entire tail boom section parted from the aircraft.
It is concluded that the most likely cause of the accident was a planetary gear failure in the second stage of the two stage epicyclic main gearbox reduction gear; the associated metal debris caused jamming within the rotating assemblies, generating forces which fractured the common epicyclic ring gear and the main gearbox casing. This resulted in the gross instability in the rotor system, which caused blades to strike the fuselage.
The initial cause of the accident was due to the mistaken health monitoring of the gearbox, leading to a deterioration of the mechanical condition of the gearbox components.’
The first of two causes stated in the report was as follows:
‘The accident was caused by the disintegration of a secondary stage planet pinion [gear] within the gearbox following a seizure of its associated roller bearing.’
The break-up of the second stage planet gear in this accident was precipitated by a maintenance error which allowed a severely deteriorated gear to fail. No part of the failed gear was recovered and the entire first planetary stage was missing. However, the break-up of the gear resulted in circumferential failures of the ring gear casing, above and below the epicyclic stages, together with a vertical rupture.
On 16 December 1980, an Aerospatiale SA330J Puma helicopter, 9M-SSC, crashed in a swamp forest near Kuala Belait in the State of Brunei. The crew of two and all 10 passengers were fatally injured in the accident, which resulted from an MGB failure similar to that which occurred on G‑REDL. The MGB of the SA330J is fundamentally similar in layout to those of the AS332 series of helicopters, although the components are not interchangeable and the gear material specifications are different. The gearbox in the 9M-SSC accident had a recent history of quantities of metallic debris being found on the magnetic chip detector in the main module. The epicyclic module was not equipped with a detector.
The synopsis of the report on this accident contained the following:
‘The accident occurred following the loss of the main rotor assembly, together with the attached bell housing containing the second stage gears of the epicyclic gearbox. Almost simultaneously, the entire tail boom section parted from the aircraft.
It is concluded that the most likely cause of the accident was a planetary gear failure in the second stage of the two stage epicyclic main gearbox reduction gear; the associated metal debris caused jamming within the rotating assemblies, generating forces which fractured the common epicyclic ring gear and the main gearbox casing. This resulted in the gross instability in the rotor system, which caused blades to strike the fuselage.
The initial cause of the accident was due to the mistaken health monitoring of the gearbox, leading to a deterioration of the mechanical condition of the gearbox components.’
The first of two causes stated in the report was as follows:
‘The accident was caused by the disintegration of a secondary stage planet pinion [gear] within the gearbox following a seizure of its associated roller bearing.’
The break-up of the second stage planet gear in this accident was precipitated by a maintenance error which allowed a severely deteriorated gear to fail. No part of the failed gear was recovered and the entire first planetary stage was missing. However, the break-up of the gear resulted in circumferential failures of the ring gear casing, above and below the epicyclic stages, together with a vertical rupture.
If anyone has access to the original accident report for 9M-SSC, they will see an Addendum containing a statement from Eurocopter that they did not agree with the root cause finding of the report. Some things never change!
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In Appendix 1 to the report, the manufacturer (at that time Aerospatiale) made various comments, some of which are included below:
‘….the assumption of the box bursting as the accident first cause is negated by the following.
-- No fragments of the missing second stage [planet gear] have been found
-- Relatively correct condition of high speed stages, which should have shown epicyclic gear jamming marks (especially on flexible couplings and torquemeter shafts)’
-- When a planet gear rupture generated by its race chippings occurs, it is necessarily preceded by the initiation of fatigue cracks through the rim
‘….the assumption of the box bursting as the accident first cause is negated by the following.
-- No fragments of the missing second stage [planet gear] have been found
-- Relatively correct condition of high speed stages, which should have shown epicyclic gear jamming marks (especially on flexible couplings and torquemeter shafts)’
-- When a planet gear rupture generated by its race chippings occurs, it is necessarily preceded by the initiation of fatigue cracks through the rim
4 Safety Recommendations
4.6 Safety Recommendation 2009-075: It is recommended that the European Aviation Safety Agency, in conjunction with Eurocopter, urgently review the design, operational life and inspection processes of the planet gears used in the epicyclic module of the Main Rotor Gearbox installed in AS332 L2 and EC225LP helicopters, with the intention of minimising the potential of any cracks progressing to failure during the service life of the gears.
4.11 Safety Recommendation 2011-036: It is recommended that the European Aviation Safety Agency (EASA) re-evaluate the continued airworthiness of the main rotor gearbox fitted to the AS332 L2 and EC225 helicopters to ensure that it satisfies the requirements of Certification Specification (CS) 29.571 and EASA Notice of Proposed Amendment 2010-06.
4.14 Safety Recommendation 2011-043: It is recommended that Eurocopter introduce a means of warning the flight crew, of the AS332 L2 helicopter, in the event of an epicyclic magnetic chip detector activation.
4.6 Safety Recommendation 2009-075: It is recommended that the European Aviation Safety Agency, in conjunction with Eurocopter, urgently review the design, operational life and inspection processes of the planet gears used in the epicyclic module of the Main Rotor Gearbox installed in AS332 L2 and EC225LP helicopters, with the intention of minimising the potential of any cracks progressing to failure during the service life of the gears.
4.11 Safety Recommendation 2011-036: It is recommended that the European Aviation Safety Agency (EASA) re-evaluate the continued airworthiness of the main rotor gearbox fitted to the AS332 L2 and EC225 helicopters to ensure that it satisfies the requirements of Certification Specification (CS) 29.571 and EASA Notice of Proposed Amendment 2010-06.
4.14 Safety Recommendation 2011-043: It is recommended that Eurocopter introduce a means of warning the flight crew, of the AS332 L2 helicopter, in the event of an epicyclic magnetic chip detector activation.
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aheoe26104 @ #784
The barbeque plate is attached to the fuselage structure at its forward right corner and its rear left corner. Looking at the photo its points of attachment at the front are to the piece of fuselage (yellowish) which is shown to be bent upwards, so it has been distorted to some extent as far as I can tell. Whether this has happened at the start of the tragic event or on impact with the ground who can say?
Unfortunately we can't see the area of rear attachment.
The barbeque plate is attached to the fuselage structure at its forward right corner and its rear left corner. Looking at the photo its points of attachment at the front are to the piece of fuselage (yellowish) which is shown to be bent upwards, so it has been distorted to some extent as far as I can tell. Whether this has happened at the start of the tragic event or on impact with the ground who can say?
Unfortunately we can't see the area of rear attachment.
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I remember in 1997, when a SA330J had a sudden stop after a freewheel #2 had a sort of slippage during the starting procedures... Because the SA330J has not tripletach, the captain was unable to notice that the second engine had not engaged... of course, the Eurocopter + operator, have pointed the fault to the captain for that... you can imagine, the helicopter has no advisory or instrument about the N2(Nf or Ntl) and the fault was from captain!!!
If anyone has access to the original accident report for 9M-SSC, they will see an Addendum containing a statement from Eurocopter that they did not agree with the root cause finding of the report. Some things never change!
I remember in 1997, when a SA330J had a sudden stop after a freewheel #2 had a sort of slippage during the starting procedures... Because the SA330J has not tripletach, the captain was unable to notice that the second engine had not engaged... of course, the Eurocopter + operator, have pointed the fault to the captain for that... you can imagine, the helicopter has no advisory or instrument about the N2(Nf or Ntl) and the fault was from captain!!!
AH are in a terrible position; If they genuinely believe that the accident was caused by other factors than the gearbox (and surely they must) then all they can really say is that there is no reason to stop flying it. They can't give vent to their full suspicions for a whole variety of reasons many of them to do with liability. If they don't have private evidence to support this (surely they must)they are heading for a Gerald Ratner moment.
What couldn't they say and more to the point why wouldn't they say?
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Pittsextra
Because they are the manufacturer and a party to all this. There will certainly be liability claims. They will be legally constrained as to what they can say at this stage. They will subsequently provide evidence to the enquiry and anything they say at this stage would prejudice this. They continue to stand by their product and hope the investigation and subsequent enquiry will exonerate them.
Because they are the manufacturer and a party to all this. There will certainly be liability claims. They will be legally constrained as to what they can say at this stage. They will subsequently provide evidence to the enquiry and anything they say at this stage would prejudice this. They continue to stand by their product and hope the investigation and subsequent enquiry will exonerate them.
B'ham - when I read (for example) this:-
That doesn't sound very "legally constrained" and to not give further rational for the comment just seems very odd, especially since it isn't helpful to the aviation industry because at the very least it seems to have a major manufacturer concluding at this stage something very different to the regulator of two countries. It also suggests that they are able to conclude something that the accident investigators are not, which again seems odd.
Further (whilst not important in the context of the accident) given Airbus and Bristow are all tradable entities and this information is very much "market sensitive" one now wonders how they plan to manage the release to the market.
Airbus said it saw no need to suspend flights with the helicopter model, adding that its experts have conducted on- site inspections of the crashed helicopter parts, leading them to conclude there was no safety-of-flight risk for the fleet.
Read more: Bristow Grounds Airbus EC225 Helicopters After Norway Crash - NASDAQ.com
Read more: Bristow Grounds Airbus EC225 Helicopters After Norway Crash - NASDAQ.com
Further (whilst not important in the context of the accident) given Airbus and Bristow are all tradable entities and this information is very much "market sensitive" one now wonders how they plan to manage the release to the market.
Consider a different angle on this: they are confident they have found something that the investigators will in due course also find and then report upon. They are choosing not to say much more for a good reason, cited above: to avoid conflicts with the investigating team's timeline and desire for thoroughness and caution. (This idea paints AB helicopters as a team player. No, I have no vested interest in ABH nor AB at all).
It still makes no sense. You have to believe that AH executive have the best interests of their business at the forefront of any thinking - so to suggest there is no safety issue would be utter madness without any intelligent reason/rational. Otherwise EC225 crashes elsewhere in world in same circumstance as Norway and they are toast if that reason is a design flaw.
Likewise you have to believe that their engineering boffins are noble and stand up people so suggesting anything otherwise doesn't fit.
So if you believe all of that (and perhaps some don't) then not giving the back story to their findings is just dumb - in fact even more dumb is the inability for the other players in this not to be able to have eyes opened by any private conversations. Beyond which if it's so obvious that a multi billion dollar entity is prepared to bet the lot on a cause then why no news from "official" channels?
Likewise you have to believe that their engineering boffins are noble and stand up people so suggesting anything otherwise doesn't fit.
So if you believe all of that (and perhaps some don't) then not giving the back story to their findings is just dumb - in fact even more dumb is the inability for the other players in this not to be able to have eyes opened by any private conversations. Beyond which if it's so obvious that a multi billion dollar entity is prepared to bet the lot on a cause then why no news from "official" channels?
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I have noticed in their photos one thing seems to be consistent. Any parts the investigation team disassembled to remove have remained disassembled in subsequent photos.
Other parts remain as they found them. The rotor head hung from slings shows this also, top pins are hanging loose by the struts and lower plates / pins are as they were on the table. One on, one off. The only exception is various nappy pins reinserted.
I think this supports the conclusion that one lower bracket was removed at the crash site.
Other parts remain as they found them. The rotor head hung from slings shows this also, top pins are hanging loose by the struts and lower plates / pins are as they were on the table. One on, one off. The only exception is various nappy pins reinserted.
I think this supports the conclusion that one lower bracket was removed at the crash site.
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Cteneto139 - guessing that the captain must have been held at fault for a reason. Even without the triple tach, couldn't one pick up a slipping/disengaged input by the torque spilt between engines. I realize a tq spilt is not abnormal in a puma but they must have had some reason to state that the pilot should have noted it.
ISTR the Puma didn't have a torquemeter either, just a pitch gauge so the freewheel problem wouldn't have been apparent there either. Can't remember if it had fuel flow meters though.
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Although this crash bears a significant resembelance to G-REDL, there is a big difference here (to me) in the failure mode. G-REDL report states that:
"The upper section of the gearbox
assembly, which included the remains of the second stage of the epicyclic
reduction gearbox, the conical housing and all three lift struts, had detached
from the MGB and were recovered with the rotor head."
So the second stage epicyclic gearbox AND conical housing had broken free and remained with the rotor head. This being consistent with the finding that the gearbox casing had been burst open, due to the broken planetary gear, and the casing fractured all the way around releasing the rotorhead. They also noted no distortion in the Barbecue plate to suggest suspension bar failure.
In this accident the conical housing does not appear to be connected to the lift bearing. Neither is the reduction gearbox section. We can clearly see the splined connection of the rotor mast suggesting it has slid out of engagement. (There is also a photograph of the rotorhead being airlifted away from the crash site to be examined and the conical housing is not visible here either - ill see if I can find it...).
The splined connection cannot simply "slide out" of engagement unless whatever is holding it in place is released (Suspension Bars/Conical housing to gearbox). IF this were another epicyclic destruction then we would surely see the same failure as in G-REDL, with half the planetary gears or at least the conical housing still attached as the failure of the gearcasing would be at the outer gear ring.
The Barbecue plate also seems very bent upwards on the front edge, which would be consistent with a rear suspension bar failure and rotor disc pitching forward - but could this damage have occured during the impact with land?
The amount of panels, cowlings and air intake screens scattered suggests to me the rotor struck the front of the aircraft rather than the tail boom during the break up.
With this in mind, it could be the reason that AH are so adament this is not a mechanical fault within the gearbox. And I would have to agree on that basis. An epicyclic failure would rupture the gearbox casing and, as in G-REDL, it would still be attached to the rotorhead. In this case the rotor mast has slid out of its splined engagement which suggests whatever holds it in place did not do so.... And if that pin was indeed missing from the suspension bar eye....
Only time will tell.
"The upper section of the gearbox
assembly, which included the remains of the second stage of the epicyclic
reduction gearbox, the conical housing and all three lift struts, had detached
from the MGB and were recovered with the rotor head."
So the second stage epicyclic gearbox AND conical housing had broken free and remained with the rotor head. This being consistent with the finding that the gearbox casing had been burst open, due to the broken planetary gear, and the casing fractured all the way around releasing the rotorhead. They also noted no distortion in the Barbecue plate to suggest suspension bar failure.
In this accident the conical housing does not appear to be connected to the lift bearing. Neither is the reduction gearbox section. We can clearly see the splined connection of the rotor mast suggesting it has slid out of engagement. (There is also a photograph of the rotorhead being airlifted away from the crash site to be examined and the conical housing is not visible here either - ill see if I can find it...).
The splined connection cannot simply "slide out" of engagement unless whatever is holding it in place is released (Suspension Bars/Conical housing to gearbox). IF this were another epicyclic destruction then we would surely see the same failure as in G-REDL, with half the planetary gears or at least the conical housing still attached as the failure of the gearcasing would be at the outer gear ring.
The Barbecue plate also seems very bent upwards on the front edge, which would be consistent with a rear suspension bar failure and rotor disc pitching forward - but could this damage have occured during the impact with land?
The amount of panels, cowlings and air intake screens scattered suggests to me the rotor struck the front of the aircraft rather than the tail boom during the break up.
With this in mind, it could be the reason that AH are so adament this is not a mechanical fault within the gearbox. And I would have to agree on that basis. An epicyclic failure would rupture the gearbox casing and, as in G-REDL, it would still be attached to the rotorhead. In this case the rotor mast has slid out of its splined engagement which suggests whatever holds it in place did not do so.... And if that pin was indeed missing from the suspension bar eye....
Only time will tell.
