North Sea Helicopter ditching 10th May 2012
I think I'm with HC on this one, sometimes a little information is not always the best thing. The chances of the crew noticing and then reporting back to base the additional vibration associated with a shaft in the gearbox developing a crack (note not yet broken, just developing) over and above all the vast amount of other vibrations that a helicopter routinely produces just in normal operation are about 4/5ths of **** all. There may have been a vibration problem with this ac, but I would be gobsmacked if, in this case, it were to do with the shaft in question.
HC....most of the offshore workers understand we enjoy spending all that money they think we make....thus are not going to willingly, knowingly, and with malice a fore foot....do ourselves in before getting back to the beach.
We cannot all be suicidal.....can we?
We might take a duff machine but it will not be intentional.
We cannot all be suicidal.....can we?
We might take a duff machine but it will not be intentional.
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Once upon a time I walked out to the aircraft wearing a Kamikaze headband which the pax thought quite funny. Of course that was in the days when people had a sense of humour and my actions were not recorded on mobile phones, displayed on Youtube, then the front page of The Sun and subsequently half the country were baying for my blood. I would, of course, be sacked the same day following interviews with the Police, Mi5, someone looking for publishing rights and a lawyer insisting that I sue the company for false dismissal.
Aviation used to be fun. You tell the young 'uns today and they just won't believe you.
Aviation used to be fun. You tell the young 'uns today and they just won't believe you.
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Baby Gravy
In all fairness I was only passing on info passed on by our OIM - The data could have been analysed back onshore and probably was.
Im trying to enter into a proactive discussion to find out some facts.
Assumption is the mother of all f**k ups. That one goes both ways the last time I checked.
For the record in the 12 years Ive worked offshore Ive not heard one bad remark about the pilots or the money they earn. Nobody cares what you earn. We just want to get home safe and sound just like you.
Being stuck out here can be frustrating at times when were fogged on or the weathers up etc, but I can assure you the vast majority of us appreciate the efforts the pilots and crews put in to get us to work and back again in on piece.
T
Im trying to enter into a proactive discussion to find out some facts.
Assumption is the mother of all f**k ups. That one goes both ways the last time I checked.
For the record in the 12 years Ive worked offshore Ive not heard one bad remark about the pilots or the money they earn. Nobody cares what you earn. We just want to get home safe and sound just like you.
Being stuck out here can be frustrating at times when were fogged on or the weathers up etc, but I can assure you the vast majority of us appreciate the efforts the pilots and crews put in to get us to work and back again in on piece.
T
Questions for Helicomparator.
Why use welding at all to join gear wheels to shafts? That seems like an invitation for trouble.
Why not use a technique (I don't know the correct name; possibly shrink-fitting) whereby the two components are machined to a very tight interference fit, then the shaft gets chilled with liquid nitrogen, the gear wheel gets heated and after the two components are joined and once temperature normalises, the resulting joint is as good as machining the two components from one solid piece of metal?
From what I've been told, welding will always create some kind of stress raiser in metal, no matter what heat-stress-relieving process gets employed after welding.
If this technique is good enough for railway carriage wheels, it ought to be good enough for helicopter gearboxes.
Why use welding at all to join gear wheels to shafts? That seems like an invitation for trouble.
Why not use a technique (I don't know the correct name; possibly shrink-fitting) whereby the two components are machined to a very tight interference fit, then the shaft gets chilled with liquid nitrogen, the gear wheel gets heated and after the two components are joined and once temperature normalises, the resulting joint is as good as machining the two components from one solid piece of metal?
From what I've been told, welding will always create some kind of stress raiser in metal, no matter what heat-stress-relieving process gets employed after welding.
If this technique is good enough for railway carriage wheels, it ought to be good enough for helicopter gearboxes.
Colibri - I am flattered that you direct your question to me, but as a pilot, not a metallurgist, sorry but I don't have a clue! However I do understand that this component has always been welded together - the modification for the 225 over 332L is just to do with the treatments. As such the welded-together concept has proven itself over millions of flight hours.
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The power consumption of turbine oil pumps is pretty low. My best guess would be less than 10hp for these engines. That leads to comparatively 'low quality' driveshaft arrangements. Remember that a number of cars use plastic water and oil pump drive assemblies due to those low power requirements.
Shrink fit shaft arrangments tend not to be preferred because their strength is highly dependent upon fabrication tolerances - hence the use of splines in the majority of high power applications.
In theory reasonable quality control should mean these sort of shafts are 'fit and forget'. But if it can do wrong, sooner or later I suppose it will and that seems to be what happened here.
The saving grace in this case was the 30 min emergency system and good decision making by the crew.
Shrink fit shaft arrangments tend not to be preferred because their strength is highly dependent upon fabrication tolerances - hence the use of splines in the majority of high power applications.
In theory reasonable quality control should mean these sort of shafts are 'fit and forget'. But if it can do wrong, sooner or later I suppose it will and that seems to be what happened here.
The saving grace in this case was the 30 min emergency system and good decision making by the crew.
My thanks must go to the Bristow S-92 crew who brought the Norway cab out for us yesterday. We often take you blokes for granted, don't we? Anyhoo, a question if I may? Could only see the RHS pilot, but noted you in your bonedome. Is this because of that 4R pulsing?
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Tris:
Do your best to keep a thick skin, we all get a little defensive and the trouble we aircrew have is the sense that few people out there, for some reason or another, have a gripe (whether within our own company or by customer etc) we rarely hear any thanks but often feel the hot breath of some unhappy soul down our necks. Forgive the chronic defensiveness especially as this sort of subject can lead to aircrew being perceived (incorrectly) as borderline suicidal apathetic nut jobs by people who become aggressively involved in distribution of misinformation (not accusing of such).
The point that is being challenged in your comment is the ability to send "data back to the beach", (apologies if that's a misquote) as there is no facility to do so other than picking up a phone and describing to an engineer what the heli is doing. The analysis of HUMS data is carried out on return to base when the card is removed from the aircraft and downloaded to a HUMS desktop station. Also, the ability to detect a vibration related to this particular failure through your back side is borderline impossible until shortly before the failure itself takes place. Any excessive, or abnormal vibration associated with the gearbox would most likely result in the aircraft being shutdown on the rig, or if in flight: a great deal of arse puckering and brow sweat. Leading to the expectation that this information being distributed by the OIM is misleading (not necessarily their intention) when done so in the context of the accident as there is not any known connection between it and this report of vibration.
More likely would be a blade out of track/balance or some other less critical issue.
Hope this helps.
Interesting heard yesterday: apparently ConocoPhillips are not flying pumas anywhere in the world just now, until the AAIB have concluded their investigation. Busy old time for the S92s in ABZ?
Do your best to keep a thick skin, we all get a little defensive and the trouble we aircrew have is the sense that few people out there, for some reason or another, have a gripe (whether within our own company or by customer etc) we rarely hear any thanks but often feel the hot breath of some unhappy soul down our necks. Forgive the chronic defensiveness especially as this sort of subject can lead to aircrew being perceived (incorrectly) as borderline suicidal apathetic nut jobs by people who become aggressively involved in distribution of misinformation (not accusing of such).
The point that is being challenged in your comment is the ability to send "data back to the beach", (apologies if that's a misquote) as there is no facility to do so other than picking up a phone and describing to an engineer what the heli is doing. The analysis of HUMS data is carried out on return to base when the card is removed from the aircraft and downloaded to a HUMS desktop station. Also, the ability to detect a vibration related to this particular failure through your back side is borderline impossible until shortly before the failure itself takes place. Any excessive, or abnormal vibration associated with the gearbox would most likely result in the aircraft being shutdown on the rig, or if in flight: a great deal of arse puckering and brow sweat. Leading to the expectation that this information being distributed by the OIM is misleading (not necessarily their intention) when done so in the context of the accident as there is not any known connection between it and this report of vibration.
More likely would be a blade out of track/balance or some other less critical issue.
Hope this helps.
Interesting heard yesterday: apparently ConocoPhillips are not flying pumas anywhere in the world just now, until the AAIB have concluded their investigation. Busy old time for the S92s in ABZ?
Last edited by teej5536; 17th May 2012 at 11:03.
I think the emergency lube becomes slightly irrevelant when you have an unsupported shaft loose in the gearbox. Metal was being made hence the chip caption. The only option here is to do what the Captain did. Emergency lube is for loss of oil, not for a catastrophic failure of a gearbox component. EC obviously thought that this would never happen otherwise you wouldn't put both pumps on the same shaft.
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As they should ironchefflay as it is a great help.
I know from experience though that the failure rate of comms is a bit higher then most expect. Sat Comm calls don't go through the first time every time and they are not clear as a bell every time either.
Looking at the data side, and I do every day all day, you can have failures there as well which was really my point that real time monitoring would be difficult but not impossible if done in a manner that fit.
I know from experience though that the failure rate of comms is a bit higher then most expect. Sat Comm calls don't go through the first time every time and they are not clear as a bell every time either.
Looking at the data side, and I do every day all day, you can have failures there as well which was really my point that real time monitoring would be difficult but not impossible if done in a manner that fit.
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Not sure about the emlube 'not being the saving grace' in this incident, it certainly played a part.
Without doubt, this was a particularly nasty failure in the MGB and could, in itself, have led to a very different outcome.
No oil pumps = no oil pressure = no MGB lubrication. My point is that emlube does what it says on the label and provides limited lubrication (and some cooling) to the GB, without it we run the additional risk of an MGB seizure, and that would definitely have resulted in a very different outcome.
Without doubt, this was a particularly nasty failure in the MGB and could, in itself, have led to a very different outcome.
No oil pumps = no oil pressure = no MGB lubrication. My point is that emlube does what it says on the label and provides limited lubrication (and some cooling) to the GB, without it we run the additional risk of an MGB seizure, and that would definitely have resulted in a very different outcome.
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FWIW the S92 had historical issues with vespel splines on its pumps and no EMlub system, just a useless bypass switch which does nothing unless you have a cooler leak. We're still waiting for the revised MRGB which will hopefully have increased durability, although with a phase 3 MRGB housing crack in Denmark recently we still appear to have some way to go wrt. QA/QC/design.
IMHO a long way to go in improving our current designs in several A/C types, kudos to the bus drivers for making the right decision in this case.
Safe flying
Max
IMHO a long way to go in improving our current designs in several A/C types, kudos to the bus drivers for making the right decision in this case.
Safe flying
Max
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Late to join this one - congrats the crew for a great decision and defaulting to the safest action. Hope I get to work with people like you.
Also I guess the write off of the hull will marginally increase the value of every other 225 in service. So the companies should send the pilots a commission.
The oil companies should send them a bonus for not risking
a.potential loss of personnel by persisting with flight and
b. not crashing onto a platform helideck risking a billion dollar facility.
well done crew. fwiw.
DD
Also I guess the write off of the hull will marginally increase the value of every other 225 in service. So the companies should send the pilots a commission.
The oil companies should send them a bonus for not risking
a.potential loss of personnel by persisting with flight and
b. not crashing onto a platform helideck risking a billion dollar facility.
well done crew. fwiw.
DD
A dedication to the superb Bond pilots who carried out a flawless ditching on 10th May:
The fighter pilot's prayer: "Lord I pray for the eyes of an eagle, the heart of a lion, the agility of an antelope, the cunning of a fox and the balls of a helicopter pilot."
The fighter pilot's prayer: "Lord I pray for the eyes of an eagle, the heart of a lion, the agility of an antelope, the cunning of a fox and the balls of a helicopter pilot."