EC225 crash near Bergen, Norway April 2016
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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.
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.
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?"
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?"
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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?"
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?"
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.
Last edited by n305fa; 16th May 2016 at 07:47.
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.
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.
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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.
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.
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
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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.
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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"
"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"
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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.
Last edited by n305fa; 16th May 2016 at 19:24.
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?"
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?"
Colibri
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.
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 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.
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"Industry Insider" - you are absolutely correct - the stakes are extremely high - much more so than in a singe incident report. two ditchings and two fatal hull losses in around five years means that the consequences could be very grave indeed. However, as you conceed Colibri49's question will have to be answered at some point - just with concrete evidence to support it. AH continue to maintain that the Pumas are safe to fly, the AIBN and AAIB, for now at least, while they don't go so far as to disagree are insisting on precautionary groundings.
The problem is detailed investigations take time. It may not even be possible to definitively determine the root cause as the evidence to do so may be at the bottom of the sea.
In the absence of detailed evidence people will have to make their own highly subjective judgements - inevitably this has already started ...
https://www.flightglobal.com/news/ar...copter-425041/
For all concerned let's hope it is possible for the AIBN to come to a conclusion sooner rather than later. But as you correctly point out they are not going to be pressured into to doing so without solid facts
The problem is detailed investigations take time. It may not even be possible to definitively determine the root cause as the evidence to do so may be at the bottom of the sea.
In the absence of detailed evidence people will have to make their own highly subjective judgements - inevitably this has already started ...
https://www.flightglobal.com/news/ar...copter-425041/
For all concerned let's hope it is possible for the AIBN to come to a conclusion sooner rather than later. But as you correctly point out they are not going to be pressured into to doing so without solid facts
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How long can a presumed criminal be held in custody without charges? So far, the AIBN hasn't come up with any evidence, none, zilch, that this accident was caused by a manufacturing or design flaw of the transmission. Airbus Helicopters clearly thinks that the transmission wasn't to blame here.
It may be best, at this point, to remove all restrictions, due to lack of evidence, and let industry decide if they want to operate the 225.
It may be best, at this point, to remove all restrictions, due to lack of evidence, and let industry decide if they want to operate the 225.
Last edited by letmein; 17th May 2016 at 21:49.
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After reading the initial report, the picture of the Suspension Bars look suspicious to me.
Someone has already stated this on here already but it is very interesting - something does not seem to add up.
The photograph of the detached rotorhead lying on the hillside with the suspension bar sticking up, shows NO bracket. We can then assume the bracket is still connected to the fuselage. However, in the report photographs, it shows the Suspension Bars, brackets and all pins in good condition. Now that is impossible! In order for the suspension bar to become seperated from the bracket (as we see in the rotor head picture as it was found) then either the bracket eye has broken releasing the bar, the pin has sheared releasing the bar or the bar ends have broken. NONE of these things have happened!? So how did it seperate if all components are present and correct?? And its unlikely the accident investigators removed them as some have previously suggested, as the other bar is still complete. Also the final photo of the report shows the suspended rotor head with bars attached - surely they would have re-instated the bracket for that photo if they had previously removed it?
The only explanation is it has been incorrectly assembled, but even then if the pin did fall out, what are the chances of finding both the pin AND nappy pin in the wreckage? Either that or that is not the pin, nappy pin or bracket.....
Something doesn't add up here.
Someone has already stated this on here already but it is very interesting - something does not seem to add up.
The photograph of the detached rotorhead lying on the hillside with the suspension bar sticking up, shows NO bracket. We can then assume the bracket is still connected to the fuselage. However, in the report photographs, it shows the Suspension Bars, brackets and all pins in good condition. Now that is impossible! In order for the suspension bar to become seperated from the bracket (as we see in the rotor head picture as it was found) then either the bracket eye has broken releasing the bar, the pin has sheared releasing the bar or the bar ends have broken. NONE of these things have happened!? So how did it seperate if all components are present and correct?? And its unlikely the accident investigators removed them as some have previously suggested, as the other bar is still complete. Also the final photo of the report shows the suspended rotor head with bars attached - surely they would have re-instated the bracket for that photo if they had previously removed it?
The only explanation is it has been incorrectly assembled, but even then if the pin did fall out, what are the chances of finding both the pin AND nappy pin in the wreckage? Either that or that is not the pin, nappy pin or bracket.....
Something doesn't add up here.
industry insider
Your response "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." is undeniable and my question has always been largely rhetorical, because short of someone close to the investigation giving out this kind of information, I never really expected a direct answer.
However if that Norwegian EC225 gearbox had been making even the slightest metal particles from the epicyclics or mast area, then it must be in the engineering records. With the tragedy of REDL fresh in people's minds, there's no way that the aircraft would have been allowed to continue operating and Airbus Helicopters would very likely be insisting that all EC225 and Mk2 types remain grounded. They're not, at least that's not how their announcements seem to me.
While I wouldn't want to see any rush to get Super Puma types back into service before as much certainty as possible has been reached, "letmein" has a point in his submission above.
Your response "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." is undeniable and my question has always been largely rhetorical, because short of someone close to the investigation giving out this kind of information, I never really expected a direct answer.
However if that Norwegian EC225 gearbox had been making even the slightest metal particles from the epicyclics or mast area, then it must be in the engineering records. With the tragedy of REDL fresh in people's minds, there's no way that the aircraft would have been allowed to continue operating and Airbus Helicopters would very likely be insisting that all EC225 and Mk2 types remain grounded. They're not, at least that's not how their announcements seem to me.
While I wouldn't want to see any rush to get Super Puma types back into service before as much certainty as possible has been reached, "letmein" has a point in his submission above.
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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?"
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?"
Having seen a number of "open" 332 &225 gearboxes in my time I can say there is no channelling of oil to the epi chip detector. There is a ridge around the edge of the outer module separator plate with a small depression in it where the epi chip detector sits. It's shown in fig 11 of the REDL report. As described to me on a course at EC/AH the Epicyclic chip detector relies chips being flung into its influence by the epicyclic system and by oil draining past the detector not by oil channelling.
Since REDL the procedures for assessing any particles found in the MGB has changed significantly.
Last edited by n305fa; 17th May 2016 at 20:56.
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Excuse my French, but why is it that EASA are approving helicopters to fly and the local authorities grounds them.....I would have thought and hoped that it was EASA as the regular authority who either approves or denies aircrafts to fly, isn't it the beauty of EASA/EU???
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How long can a presumed criminal be held in custody without charges? So far, the AIBN hasn't come up with any evidence, none, zilch, that this accident was caused by a manufacturing or design flaw of the transmission. Airbus Helicopters clearly thinks that the transmission wasn't to blame here.
It may be best, at his point, to remove all restrictions, due to lack of evidence, and let industry decide if they want to operate the 225.
It may be best, at his point, to remove all restrictions, due to lack of evidence, and let industry decide if they want to operate the 225.
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How long can a presumed criminal be held in custody without charges? So far, the AIBN hasn't come up with any evidence, none, zilch, that this accident was caused by a manufacturing or design flaw of the transmission. Airbus Helicopters clearly thinks that the transmission wasn't to blame here.
It may be best, at his point, to remove all restrictions, due to lack of evidence, and let industry decide if they want to operate the 225.
It may be best, at his point, to remove all restrictions, due to lack of evidence, and let industry decide if they want to operate the 225.
Let's not forget the investigation is still in its early stages with a search for significant items still ongoing. It's easy for us to sit at our computers hypothesising but the investigation can only publish factual information and their analysis of those facts. I assume that if there were facts relating to the airworthiness of the 225/332 the AIBN , Norwegian CAA,UK CAA and EASA would issue something.
However frustrating it is, we have no option but to wait for the investigation to turn up something to either eliminate potential causes or focus the investigation on a particular issue. I've no doubt that there is significant pressure on the investigation team to find the cause or causes of this tragic event.
Tightgit
They also haven't come up with any evidence that it wasn't the gearbox that failed. However, a sobering picture of a full set of rotorblades 'gently' lowering themselves onto terra firma sans helicopter is evidence that something wasn't quite right!