North Sea heli ditching: Oct 2012
Keep the posts coming Riff they are mostly accurate and informative to the vast readers of this thread. If some here do not understand them that is their problem.
The Sultan
The Sultan
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Riff Raff, Sultan,
You rock
. Please keep up the questions and information from guys who seem to have no ax to grind but want pure information. I'm mostly a 'lurker' but I love the way that so many guys here just ask relevant questions in an attempt to get relevant answers
You rock
. Please keep up the questions and information from guys who seem to have no ax to grind but want pure information. I'm mostly a 'lurker' but I love the way that so many guys here just ask relevant questions in an attempt to get relevant answers
Talking relevance - top of page 5 latest AAIB report, the cracks started and grew to failure in areas of the shaft that had not nor were required to be surface hardened.
The shaft on the CHC machine was it would seem from the latest AAIB report likely to be the highest time shaft on any 225...
That and the question mark on the use and function of HUMS which is now something of focus - EC don't look the smartest frankly.
The shaft on the CHC machine was it would seem from the latest AAIB report likely to be the highest time shaft on any 225...
That and the question mark on the use and function of HUMS which is now something of focus - EC don't look the smartest frankly.
Pitts, on the subject of shaft age, I'm not sure why you suspect it is particularly old. The first Bristow machines were delivered in 2005 so their shafts were probably built in 2004 so would be close to twice the calendar age. Whilst CHC overhaul their own MGBs at HeliOne (and so get the same shafts back from overhaul) Bristow uses power-by-the-hour so without checking the log cards I couldn't be certain that we have older shafts, but I would strongly suspect so.
HC - Hi. The latest AAIB report says that no EC225 shaft had covered 4000 hours and that the shaft fitted to CHC's machine had 3800 or so. (sorry don't have the report to hand to give exact number). So on the basis nothing has got to 4000 and the one in the sea in October was 3800...
One thing I find incredible with story is how some of these odd decisions are almost accepted.
You have some guy fly a Gazelle into a hill or some private owner suggest a new crazy scheme and everyone scoffs or calls everyone involved stupid etc.
Yet here you have one of the biggest manufacturers make at best questionable decisions with so far little insight to what testing has been done and the silence is deafening. I mean the latest AAIB report suggests part of the ongoing investigation is around the suitability of the material selected.. Really?!
One thing I find incredible with story is how some of these odd decisions are almost accepted.
You have some guy fly a Gazelle into a hill or some private owner suggest a new crazy scheme and everyone scoffs or calls everyone involved stupid etc.
Yet here you have one of the biggest manufacturers make at best questionable decisions with so far little insight to what testing has been done and the silence is deafening. I mean the latest AAIB report suggests part of the ongoing investigation is around the suitability of the material selected.. Really?!
Oh yes, it does say that no shaft has exceeded 4000 hrs which is a bit surprising. Our oldest airframe must be pushing 10,000 hrs by now so I suppose it must be just the PBH thing has meant that these older airframes happen to have younger shafts in them.
When this shaft is lifed at 20k hours and airframes with 10k hours you might think you would still have shafts older than 3845hours?
although makes you wonder where the 20000 hour life number for this shaft comes from...
although makes you wonder where the 20000 hour life number for this shaft comes from...
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....Anyway, the gear teeth are not particularly in discussion, they didn't fail, the shaft failed!.....
Your point is valid, but there still may be some questions about how the change in material and processing made specifically for this model MGB may have affected the weld quality.
For example, with carburizing (ie. the process used prior to the EC225) it is standard practice to mask off any surfaces that are not to be case hardened using copper plate, and then the copper plate masking is removed after carburizing. Also, since there tends to be quite a bit of quench distortion with carburizing, especially in areas with thin cross section, the carburized half of the shaft would likely be 100% machined around the weld joint surfaces after heat treatment to provide accurate fit-up for the weld joint. This post heat treat machining operation would remove any surface contamination and providing very clean material for welding.
However, with nitriding (ie. the process used for the EC225) it is common practice to nitride the entire surface of the part. While masking (tin or copper plate) can be used with nitriding, this step is commonly eliminated to save cost, and also because the nitride case can have a beneficial effect on fatigue. Another very important processing step that must be taken after nitriding is removal of the thin outer "white layer". This white layer is composed of iron nitrides, and is very brittle and full of microfractures. It can be removed through mechanical means such as grit blast, or by chemical etching. Given the presence of surface corrosion on the inside surface of the shaft, and that the shaft fractures initiated from the inside surface of the shaft rather than the more highly stressed outside surface (as one would expect for a typical reverse cyclic bending failure), it seems conceivable that the weld integrity may have been compromised by contamination left behind on the inside shaft surface after nitriding/heat treatment.
As always, just pure speculation on my part. But that's what makes these forums fun!
Riff Raff:
Thanks for your interesting posting.
I agree with your general comments on differences on carburizing vs nitriding.
Actually, as you pointed out, we are speculating, because we do not know the actual process applied on the subject gear .
Anyway, on my similar personal experiences, I have seen that on vital parts:
- the "white layer" is removed, with one of the methods you listed
- copper plating is used to mask areas not to be hardened
As far as the weld is concerned, I imagine that in any case the two mating areas of the two "half shfts" are machined to provide a correct match and a good clean diameters and planar surface before welding, tolerances at this stage are usually too tight to leave them as they are.
Thanks for your interesting posting.
I agree with your general comments on differences on carburizing vs nitriding.
Actually, as you pointed out, we are speculating, because we do not know the actual process applied on the subject gear .
Anyway, on my similar personal experiences, I have seen that on vital parts:
- the "white layer" is removed, with one of the methods you listed
- copper plating is used to mask areas not to be hardened
As far as the weld is concerned, I imagine that in any case the two mating areas of the two "half shfts" are machined to provide a correct match and a good clean diameters and planar surface before welding, tolerances at this stage are usually too tight to leave them as they are.
Last edited by dascanio; 3rd Dec 2012 at 11:35.
I agree with your general comments on differences on carburizing vs nitriding.
Actually, as you pointed out, we are speculating, because we do not know the actual process applied on the subject gear .
Actually, as you pointed out, we are speculating, because we do not know the actual process applied on the subject gear .
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Originally Posted by Pitts
I agree with your general comments on differences on carburizing vs nitriding.
Actually, as you pointed out, we are speculating, because we do not know the actual process applied on the subject gear .
Actually, as you pointed out, we are speculating, because we do not know the actual process applied on the subject gear .
Si
Last edited by bigglesbutler; 3rd Dec 2012 at 12:53.
When at the top of page 5 in the latest AAIB report says:-
On G-REDW and G-CHCN, the cracks initiated and grew to failure in areas of the vertical shaft that had not been, nor were required to be, surface hardened.
So perhaps its more valuable to discuss the material used ahead of the hardening process.
On G-REDW and G-CHCN, the cracks initiated and grew to failure in areas of the vertical shaft that had not been, nor were required to be, surface hardened.
So perhaps its more valuable to discuss the material used ahead of the hardening process.
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PITTS - I see no value in you discussing anything in relation to the metallurgy of these components. You think you know what you are talking about......and that makes you dangerous!!!
DB
DB
DB - I see this is fitting the usual pattern which is we all become 10 years old again and run around calling each other names. Well done.
The thing is you have no idea who I am, what I do, what I have done. It is a joke to call me dangerous when frankly Sir it is you who likes to give it the big one around all your flying hours, your airmanship, risk management and yet where was your risk management, your airmanship around the flying of the EC225?
The thing is you have no idea who I am, what I do, what I have done. It is a joke to call me dangerous when frankly Sir it is you who likes to give it the big one around all your flying hours, your airmanship, risk management and yet where was your risk management, your airmanship around the flying of the EC225?
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Pitts are you J Ferguson in disguise as you seem to be rubbing more and more people up the wrong way. So pray tell what IS your background's apart from a PPL holder?
Si
Si
Last edited by bigglesbutler; 3rd Dec 2012 at 17:51.
As you wish biggles. It seems to me the people getting stressed are in a camp labeled "vested interest".
Sorry the point about being a PPL holder is? Is that supposed to a jibe or a sneer?
Tell you what take it I have zero hours, didn't go to a decent uni, no professional career, no funds and no experience in anything.
So you educate me on how surface hardening (lets call it nitriding) affected this shaft. Then once you have done that perhaps explain that HUMS data and then put the cherry on the cake and tell everyone how everyone seems comfortable when the shaft that failed in October was almost certainly the highest time on any EC225, and again to quote from the AAIB report, no EC225 shaft has flown 4000hrs - when EC love to trot out the 250000hrs statistic which is relevant how?
Sorry the point about being a PPL holder is? Is that supposed to a jibe or a sneer?
Tell you what take it I have zero hours, didn't go to a decent uni, no professional career, no funds and no experience in anything.
So you educate me on how surface hardening (lets call it nitriding) affected this shaft. Then once you have done that perhaps explain that HUMS data and then put the cherry on the cake and tell everyone how everyone seems comfortable when the shaft that failed in October was almost certainly the highest time on any EC225, and again to quote from the AAIB report, no EC225 shaft has flown 4000hrs - when EC love to trot out the 250000hrs statistic which is relevant how?
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Pitts you've missed the point, you may be a mettalurgic genius and if you are pray enlighten us as those who have done so receive praise (par example riff-raff).
You come across as a know it all who actually knows nothing about the aircraft (from experience not reading tinternet/books etc), the environment we work in or the job we do. It's not a big deal to not know until you pretend you do and then it comes across very poorly.
I am a pilot, not an engineer, nor a chemist who knows metallurgy, but I have a technical mind and can absorb wise words from people who are far smarter than me. Hums is a tool, material hardening is a tool, the interim reports are just that and I am awaiting many of the answers you seek. I am however using my own experience and judgement to WAIT for those answers because they will come, our industry is far too controlled for them not to. Your constant stirring is simply starting to annoy me and others, so this will be my one and only attempt to explain myself to you. If you wish to continue trolling then feel free but by doing so you will reduce the number of people willing to converse with you.
Have fun.
Si
You come across as a know it all who actually knows nothing about the aircraft (from experience not reading tinternet/books etc), the environment we work in or the job we do. It's not a big deal to not know until you pretend you do and then it comes across very poorly.
I am a pilot, not an engineer, nor a chemist who knows metallurgy, but I have a technical mind and can absorb wise words from people who are far smarter than me. Hums is a tool, material hardening is a tool, the interim reports are just that and I am awaiting many of the answers you seek. I am however using my own experience and judgement to WAIT for those answers because they will come, our industry is far too controlled for them not to. Your constant stirring is simply starting to annoy me and others, so this will be my one and only attempt to explain myself to you. If you wish to continue trolling then feel free but by doing so you will reduce the number of people willing to converse with you.
Have fun.
Si
I'm not sure how I have pretended to be an expert in anything have I? I've been free and actually very quick to tell all that I hold a PPL and I am not an ATPL EC225 pilot - for example. Except in doing so that seemed to suggest to some that my terms of reference were some how lacking - as you seem to be doing here.
I'm not interested in receiving praise, I'm not interested in trying to compare my flying experience with anyone, my education or my background because where does it lead? Do I have to scan my qualifications, take a picture of my aircraft, the house I bought with my experience in whatever? As I said its like being at school.
My interest in this is nothing to do with trolling but because I have a friend who was/is a user of this industry in the course of his work. Now obviously I agree the ultimate report will reveal all and we all wait to see what that outcomes that brings.
However waiting did not serve people all that well in this case did it? A lot of flight hours passed between 10th May and 22nd October and of course people take the decisions made by the operators and Eurocopter in good faith because why not? At some point in the future Eurocopter are going to say the EC225 is "fixed" and you are going to have to take that in good faith - again.
It is therefore surely reasonable to question the decisions made to date?
I'll give you an example. Look at page 3 of the latest AAIB report and figure 1. It shows the "learned" thresholds for alarms of a sensor called MOD-45.
I look at that data and I'd say that the mean plots for G-REDW were generally lower than G-CHCN and yet the learned Amber threshold is what? twice that of G-CHCN?
Now this HUMS data is something that is being used to give greater freedoms now in terms of flying the EC225 and will no doubt be used to give comfort in the future. Yet there seems to be absolutely no clear picture around these thresholds learned or indeed the fleet maximums.
Then combine that with the life of the shaft in G-CHCN and the stated on going work into the shaft its material and suitability for use in the future and how can you see these genuine and obviously concerns to be "trolling"??? Maybe you can have that conversation with my mates wife and see how casually she takes this.
I've got no beef with you or anyone else here and if my posts on this subject upset anyone then thats surprising given they are driven by safety.
Edited to add:- Biggles/DB you guys call me out and suggest I have no knowledge so how do you see things at this point?
I'm not interested in receiving praise, I'm not interested in trying to compare my flying experience with anyone, my education or my background because where does it lead? Do I have to scan my qualifications, take a picture of my aircraft, the house I bought with my experience in whatever? As I said its like being at school.
My interest in this is nothing to do with trolling but because I have a friend who was/is a user of this industry in the course of his work. Now obviously I agree the ultimate report will reveal all and we all wait to see what that outcomes that brings.
However waiting did not serve people all that well in this case did it? A lot of flight hours passed between 10th May and 22nd October and of course people take the decisions made by the operators and Eurocopter in good faith because why not? At some point in the future Eurocopter are going to say the EC225 is "fixed" and you are going to have to take that in good faith - again.
It is therefore surely reasonable to question the decisions made to date?
I'll give you an example. Look at page 3 of the latest AAIB report and figure 1. It shows the "learned" thresholds for alarms of a sensor called MOD-45.
I look at that data and I'd say that the mean plots for G-REDW were generally lower than G-CHCN and yet the learned Amber threshold is what? twice that of G-CHCN?
Now this HUMS data is something that is being used to give greater freedoms now in terms of flying the EC225 and will no doubt be used to give comfort in the future. Yet there seems to be absolutely no clear picture around these thresholds learned or indeed the fleet maximums.
Then combine that with the life of the shaft in G-CHCN and the stated on going work into the shaft its material and suitability for use in the future and how can you see these genuine and obviously concerns to be "trolling"??? Maybe you can have that conversation with my mates wife and see how casually she takes this.
I've got no beef with you or anyone else here and if my posts on this subject upset anyone then thats surprising given they are driven by safety.
Edited to add:- Biggles/DB you guys call me out and suggest I have no knowledge so how do you see things at this point?
Last edited by Pittsextra; 3rd Dec 2012 at 19:46.
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Pittsextra and others attracting unnecessary attention.
I personally think the days of this forum living up to its handle are long gone. ATPL, CPL, CFI or any other professional qualification seems to no longer be required on PPRUNE.
Just because some of us do have the "required" paperwork to seemingly qualify to post on this forum, does that mean we know more about machines and their construction? I have flown the EC225 now for five years. I am now converted to the S92 because of the recent events.
PPRUNE will not change the world so lets please keep up the food for thought without resorting to the old ticket holder arguments.
I would like to read all posts from whoever they are from, and make my own mind up from the contents of the posts.
I appreciate this sounds a bit stupid when I am commenting myself on others posts but I do not want anyone to feel pushed away.
Live and let live! Pittsextra, I find your posts very interesting and I am sure other layman like me do also.
Please keep your thoughts coming because one day you maybe able to say "I told you so" and that will shut a few up.
Thanks.
I personally think the days of this forum living up to its handle are long gone. ATPL, CPL, CFI or any other professional qualification seems to no longer be required on PPRUNE.
Just because some of us do have the "required" paperwork to seemingly qualify to post on this forum, does that mean we know more about machines and their construction? I have flown the EC225 now for five years. I am now converted to the S92 because of the recent events.
PPRUNE will not change the world so lets please keep up the food for thought without resorting to the old ticket holder arguments.
I would like to read all posts from whoever they are from, and make my own mind up from the contents of the posts.
I appreciate this sounds a bit stupid when I am commenting myself on others posts but I do not want anyone to feel pushed away.
Live and let live! Pittsextra, I find your posts very interesting and I am sure other layman like me do also.
Please keep your thoughts coming because one day you maybe able to say "I told you so" and that will shut a few up.Thanks.