Sikorsky S-76 down in the North Sea (Threads merged)
BIMs
In my old and bold days I flew Sikorsky designed Wessex and Seakings with similar blade designs to the S76. These blades had hollow spars pressurised with nitrogen and a BIM indicator at the root which was white if the spar was pressurised but turned to white with black stripes if the spar lost pressure due to a crack etc. A BIM may have given warning of the crack before the catastrophic failure occurred.
I believe that the S76 blade spar is a cold formed welded titanium tube which is then hot formed into the required aerofoil shape.
HM
I believe that the S76 blade spar is a cold formed welded titanium tube which is then hot formed into the required aerofoil shape.
HM
Avoid imitations
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SASless,
Precautionary advice has been promulgated by Sikorsky that blades previously involved in lightning strikes should be removed (replaced with another) prior to the next flight. The onus to keep them in service has been withdrawn from operators (unles they really want to stick their necks out!) .
I heard of one such aircraft that is now embarrassingly stuck on a ship somewhere in the Med.
Precautionary advice has been promulgated by Sikorsky that blades previously involved in lightning strikes should be removed (replaced with another) prior to the next flight. The onus to keep them in service has been withdrawn from operators (unles they really want to stick their necks out!) .
I heard of one such aircraft that is now embarrassingly stuck on a ship somewhere in the Med.
Iconoclast
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Lu
For some reason, you posted the same long post on two threads.
One now deleted.
For some reason, you posted the same long post on two threads.
One now deleted.
Last edited by Heliport; 27th Jul 2002 at 20:44.
Iconoclast
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To: Flight Safety
Isn't that what I said in my post above relative to the properties of Titanium?. There is a post I made on the Rotor blade failure forum.
Lu
Quoted passages deleted. If you want to refer to exhanges on another thread, please post a link.
I made several comments on a post that has since been removed alluding to [Edited again by Heliport]
An S-76 suffered a major lightning attachment incident and the following words are from an AAIB accident report. AAIB Bulletin No. 3/2001. Aircraft Registration Sikorsky S-76 (modified), G-BHBF This helicopter suffered major trauma and many parts were changed and many were replaced. (These are my words). Quote:…….The horizontal stabiliser was scrapped, being damaged beyond economic repair. The major components found to have been effected were returned to the manufacturer or approved overhaul agencies. In most cases no procedures for the necessary repairs existed. In other instances no effective inspection techniques appropriate to lightning events were available. Most of the major components were therefore not returned to service, but replaced using new or overhauled components. (Unquote) This question begs asking. If there were no inspection procedures in existence what criteria was used to return this blade to service? I am not implying that the lightning strike and the eventual blade failure had any thing to do with each other.
There is a post by Magbreak on the North Sea thread. Also there is an interesting post by Flight Safety on the properties of Titanium. If anyone wishes to read them, they can.
Quote: In the ASB issued at the same time as the AAIB statement Sikorsky mention 8 blades that are known to have been involved in lightning strikes. An amended version came out today stating that all blades involved in lightning strikes on the ground and in the air should be removed before the next flight. Unquote. Speculation deleted.
According to ATA regs. when an aircraft enters service the operator will receive copies of the required manusls to include a repair manual and an overhaul manual. In the case of the S-61s these manuals were never created (at least in reference to the two effected S-61s). Edited
Isn't that what I said in my post above relative to the properties of Titanium?. There is a post I made on the Rotor blade failure forum.
Lu
Quoted passages deleted. If you want to refer to exhanges on another thread, please post a link.
I made several comments on a post that has since been removed alluding to [Edited again by Heliport]
An S-76 suffered a major lightning attachment incident and the following words are from an AAIB accident report. AAIB Bulletin No. 3/2001. Aircraft Registration Sikorsky S-76 (modified), G-BHBF This helicopter suffered major trauma and many parts were changed and many were replaced. (These are my words). Quote:…….The horizontal stabiliser was scrapped, being damaged beyond economic repair. The major components found to have been effected were returned to the manufacturer or approved overhaul agencies. In most cases no procedures for the necessary repairs existed. In other instances no effective inspection techniques appropriate to lightning events were available. Most of the major components were therefore not returned to service, but replaced using new or overhauled components. (Unquote) This question begs asking. If there were no inspection procedures in existence what criteria was used to return this blade to service? I am not implying that the lightning strike and the eventual blade failure had any thing to do with each other.
There is a post by Magbreak on the North Sea thread. Also there is an interesting post by Flight Safety on the properties of Titanium. If anyone wishes to read them, they can.
Quote: In the ASB issued at the same time as the AAIB statement Sikorsky mention 8 blades that are known to have been involved in lightning strikes. An amended version came out today stating that all blades involved in lightning strikes on the ground and in the air should be removed before the next flight. Unquote. Speculation deleted.
According to ATA regs. when an aircraft enters service the operator will receive copies of the required manusls to include a repair manual and an overhaul manual. In the case of the S-61s these manuals were never created (at least in reference to the two effected S-61s). Edited
Last edited by Heliport; 27th Jul 2002 at 21:08.
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We know from discussions following other crashes that opinon amongst members is divided about whether it is right to discuss possible cause(s) of a crash before the accident investigators have completed their investigations and published their report. I think discussion is inevitable and acceptable provided that contributions are responsible.
* Making allegations against manufacturers on a public forum is a fraught with dangers for the owners of the site.
* Alleging that negligence or some other failure by a manufacturer has caused a loss of life is irresponsible. If you feel your theory is right, find a newspaper or trade journal with sufficient financial resources to test your theories and publish them if they feel sufficiently confident.
* Saying "I will admit I'm wrong if in fact I am proven wrong" doesn't change the nature of the post. Nor does adding "I'm not implying that .........." when you obviously are.
* Inviting people to "ask Nick" questions about the S-76 which relate directly or even indirectly to the North Sea crash is irresponsible and unfair. As several people have pointed out, Nick cannot possibly be expected to answer questions on this thread.
* Claiming that because somebody hasn't answered a point to your satisfaction it must be because the answer would be damaging to their company is silly. Rotorheads is the leading helicopter website, but it is not an official investigation. It's particularly unfair to do that to someone who has given so much to Rotorheads.
* Finally, if one of your posts is edited/deleted, please do not repeat the deleted material in another post.
Please look at things from the point of view of the owners of this site:
Because we post anonymously, most contributors are just 'usernames' in cyberspace. The owners have no way of knowing whether an individual member is truly the expert he claims to be, a crank with a pet theory, or a disgruntled former employee of the company being attacked.
Pprune doesn't have the facilities to check whether an allegation is right or wrong. Apart from the potential financial implications of libelling a person or company, it is also unfair to allow people or companies to be attacked on a public forum when the allegations might be totally unfounded.
Heliport
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* Making allegations against manufacturers on a public forum is a fraught with dangers for the owners of the site.
* Alleging that negligence or some other failure by a manufacturer has caused a loss of life is irresponsible. If you feel your theory is right, find a newspaper or trade journal with sufficient financial resources to test your theories and publish them if they feel sufficiently confident.
* Saying "I will admit I'm wrong if in fact I am proven wrong" doesn't change the nature of the post. Nor does adding "I'm not implying that .........." when you obviously are.
* Inviting people to "ask Nick" questions about the S-76 which relate directly or even indirectly to the North Sea crash is irresponsible and unfair. As several people have pointed out, Nick cannot possibly be expected to answer questions on this thread.
* Claiming that because somebody hasn't answered a point to your satisfaction it must be because the answer would be damaging to their company is silly. Rotorheads is the leading helicopter website, but it is not an official investigation. It's particularly unfair to do that to someone who has given so much to Rotorheads.
* Finally, if one of your posts is edited/deleted, please do not repeat the deleted material in another post.
Please look at things from the point of view of the owners of this site:
Because we post anonymously, most contributors are just 'usernames' in cyberspace. The owners have no way of knowing whether an individual member is truly the expert he claims to be, a crank with a pet theory, or a disgruntled former employee of the company being attacked.
Pprune doesn't have the facilities to check whether an allegation is right or wrong. Apart from the potential financial implications of libelling a person or company, it is also unfair to allow people or companies to be attacked on a public forum when the allegations might be totally unfounded.
Heliport
Moderator
Last edited by Heliport; 28th Jul 2002 at 16:20.
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No info on web on S76 blade contruction , If it was the same as blackhawk then one might assume it was a multi spar contruction ( similar to apache) , otherwise it would not allow for ballistic damage. Any one confirm it is multi spar contruction ?.
As I said in an earlier post the S76 blade has a single hollow titanium spar which is a cold formed welded tube which is then hot formed into the aerofoil section. Pockets are attached to the spar to complete the aerofoil section. The whole blade is then covered in a metal mesh impregnated fibreglass sheath. From the diagrams I have seen I can't discern any secondary load path.
HF
HF
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rotor construction ......
the following AAIB bulletin on G-BHBF on a lightning strike on the 17th Nov 1999 gives a good description of the Main Rotor Construction .......
http://www.aaib.dft.gov.uk/bulletin/mar01/gbhbf.htm
(this is not a report on the same machine by any chance?)
http://www.aaib.dft.gov.uk/bulletin/mar01/gbhbf.htm
(this is not a report on the same machine by any chance?)
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You've probably all seen it, but the AAIB's preliminary findings are posted in full on the main 'North Sea Crash' thread.
It might be worth bearing in mind that the report says
The bold is mine.
It might be worth bearing in mind that the report says
"At this stage, there are a number of variables that are being evaluated to determine the likely origin of the fatigue.
One variable may be related to a lightning strike suffered by the subject blade in 1999 but there are other variables under active consideration....................
At this stage, there is no evidence to link the lightning strike to the fatigue failure, however, this is one of the variables still under active consideration."
One variable may be related to a lightning strike suffered by the subject blade in 1999 but there are other variables under active consideration....................
At this stage, there is no evidence to link the lightning strike to the fatigue failure, however, this is one of the variables still under active consideration."
It's not just an adventure....
it's just a job!
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Can everyone just please wait until the other section of blade is found before they start posturing about the cause of the failure? Until they get the missing section, they cannot put the whole puzzle together.
I myself am still waiting for SHELL approval to fly and I dont think that will come until they are convinced that this is not a design problem. So lets just wait and see.
OffshoreIgor
I myself am still waiting for SHELL approval to fly and I dont think that will come until they are convinced that this is not a design problem. So lets just wait and see.
OffshoreIgor
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Well said.
Some discussion is natural, but I hope people keep to the guidelines Heliport has given. I hope Lu reads them before posting.
The AAIB are probably the best accident investigators in the world and they'll get to the bottom of what caused this tragedy. The lightening damage possibility is just one option, and it may turn out to be a complete red herring. We just don't know yet.
Jumping on little bits in a preliminary report and building them up in to something big is stupid. I suppose that's what sorts out true experts from people who claim they are.
Some discussion is natural, but I hope people keep to the guidelines Heliport has given. I hope Lu reads them before posting.
The AAIB are probably the best accident investigators in the world and they'll get to the bottom of what caused this tragedy. The lightening damage possibility is just one option, and it may turn out to be a complete red herring. We just don't know yet.
Jumping on little bits in a preliminary report and building them up in to something big is stupid. I suppose that's what sorts out true experts from people who claim they are.
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Hobie,
No it wasn't the same aircraft but it was the same base.
Having read the report one paragraph is still confusing me.
"The horizontal stabiliser was scrapped, being damaged beyond economic repair. The major components found to have been affected were returned to the manufacturers or approved overhaul agencies. In most cases no procedures for the necessary repairs existed. In other instances no effective inspection techniques appropriate to lightning events were available. Most of the major components were therefore not returned to service, but replaced using new or overhauled components."
(In flying lawyer style the bold is mine)
My questions are:
1) What exactly do Sikorsky or their approved overhaul agency do with a blade that has been hit by lightning??
2) Where the paragraph states "most of the major components were therefore not returned to service" is that a choice of the Operator, or the manufacturer?
No it wasn't the same aircraft but it was the same base.
Having read the report one paragraph is still confusing me.
"The horizontal stabiliser was scrapped, being damaged beyond economic repair. The major components found to have been affected were returned to the manufacturers or approved overhaul agencies. In most cases no procedures for the necessary repairs existed. In other instances no effective inspection techniques appropriate to lightning events were available. Most of the major components were therefore not returned to service, but replaced using new or overhauled components."
(In flying lawyer style the bold is mine)
My questions are:
1) What exactly do Sikorsky or their approved overhaul agency do with a blade that has been hit by lightning??
2) Where the paragraph states "most of the major components were therefore not returned to service" is that a choice of the Operator, or the manufacturer?
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Lu
Even though I can see why lots of people think it's wrong to speculate about causes before the official report comes out, I'm on the side of saying it's only natural to discuss so allow it as long as it's sensible.
If you keep ignoring the ground rules, this thread will end up being closed.
And it's bl**dy rude to just ignore the guidelines. Why do you always act as if you're a special case and the rules don't apply to you?
Even though I can see why lots of people think it's wrong to speculate about causes before the official report comes out, I'm on the side of saying it's only natural to discuss so allow it as long as it's sensible.
* Finally, if one of your posts is edited/deleted, please do not repeat the deleted material in another post.
And it's bl**dy rude to just ignore the guidelines. Why do you always act as if you're a special case and the rules don't apply to you?
Iconoclast
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In reply...
To: Hoverman
magbrake asked the above question and I responded. Perhaps there are other members of this forum that would like to respond to the same question. Maybe they could finesse the answer but the content of their answers will be similar to what I said in my response.
I believe that my entry into this thread was in response to a post that stated that the main spar of the rotorblades was made of Titanium. I posted some peculiarities of Titanium and another post added to it and in essence supported what I had stated and it went from there. I never stated that the lightning strike was the cause of the failure although it was alluded that I in fact did make those statements. My reference to the effects on Titanium by low or high voltage is that it would be noticeable at the point of attachment. My comments were in support of the AAIB investigating the relationship of the lightning strike to the fatigue failure of the spar. Up to now it has all been conjecture both on my part and the parts of the other contributors of this forum.
1) What exactly do Sikorsky or their approved overhaul agency do with a blade that has been hit by lightning??
I believe that my entry into this thread was in response to a post that stated that the main spar of the rotorblades was made of Titanium. I posted some peculiarities of Titanium and another post added to it and in essence supported what I had stated and it went from there. I never stated that the lightning strike was the cause of the failure although it was alluded that I in fact did make those statements. My reference to the effects on Titanium by low or high voltage is that it would be noticeable at the point of attachment. My comments were in support of the AAIB investigating the relationship of the lightning strike to the fatigue failure of the spar. Up to now it has all been conjecture both on my part and the parts of the other contributors of this forum.
Last edited by Lu Zuckerman; 29th Jul 2002 at 17:55.
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Personally, I see nothing wrong with Lu, or anyone, speculating about any helicopter related subject, as long as the author makes it absolutely clear to all, respectful of different cultural interpretations, that certian comments are purely speculative.
______________________
To not lose the 'thread' of the thread, the moderator might;
1/ e-mail a copy of the offending post to the author, with a request that he/she edits it.
2/ then delete only the offending segment(s), awaiting the author's rephrasing of them.
Just my 2-bits worth.
(to non North Americans, 2-bits means a quarter, and a quarter means 25 cents, and 25 cents means nothing - if it's Canadian quarter)
______________________
To not lose the 'thread' of the thread, the moderator might;
1/ e-mail a copy of the offending post to the author, with a request that he/she edits it.
2/ then delete only the offending segment(s), awaiting the author's rephrasing of them.
Just my 2-bits worth.
(to non North Americans, 2-bits means a quarter, and a quarter means 25 cents, and 25 cents means nothing - if it's Canadian quarter)
Last edited by Dave Jackson; 29th Jul 2002 at 18:59.
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Lu
I assume Hoverman was referring to you repeating things which had already been deleted from your earlier posts - only hours after I had expressly asked contributors not to do that. You did the same thing earlier in the thread which is what prompted me to include that particular guideline.
I have deleted it again.
The guideline was clear: "* Finally, if one of your posts is edited/deleted, please do not repeat the deleted material in another post.
I have explained both here on the forum, and by email to you, what is and is not acceptable on Pprune. I know you consider our policy on these matters to be too restrictive and a denial of free speech. You are entitled to your views. What you are not entitled to do is to deliberately post in breach of the rules.
Moderators have a responsibility to enforce the policy laid down by the Adminsitrators. We are all volunteers with other jobs, and can't monitor the forums 24 hours a day, so we rely upon members' co-operation. Usually, it works.
I'm sure there are many members who from time to time disagree with Moderators' decisions, but there are only two Rotorheads members who persistently and blatantly ignore requests: You are one of them.
I am anxious to avoid any unpleasantness over this, but there is no justification for treating you any differently from everybody else.
Please read the Guidelines (and my email) again.
If you don't like the way Pprune is run, post your views on another website - or start your own.
If you wish to continue posting here, you must abide by decisions even if you disagree with them.
Dave Jackson
1st point: You are entitled to your view. Please refer to the 'Guidelines' post above to see the Pprune view.
2nd point: If Pprune had a full-time monitoring / editorial team, what you suggest might be possible. This entire website is run by people who have other jobs and other demands on their time. We rely upon members to co-operate by abiding by policy decisions even if they disagree with them.
I assume Hoverman was referring to you repeating things which had already been deleted from your earlier posts - only hours after I had expressly asked contributors not to do that. You did the same thing earlier in the thread which is what prompted me to include that particular guideline.
I have deleted it again.
The guideline was clear: "* Finally, if one of your posts is edited/deleted, please do not repeat the deleted material in another post.
I have explained both here on the forum, and by email to you, what is and is not acceptable on Pprune. I know you consider our policy on these matters to be too restrictive and a denial of free speech. You are entitled to your views. What you are not entitled to do is to deliberately post in breach of the rules.
Moderators have a responsibility to enforce the policy laid down by the Adminsitrators. We are all volunteers with other jobs, and can't monitor the forums 24 hours a day, so we rely upon members' co-operation. Usually, it works.
I'm sure there are many members who from time to time disagree with Moderators' decisions, but there are only two Rotorheads members who persistently and blatantly ignore requests: You are one of them.
I am anxious to avoid any unpleasantness over this, but there is no justification for treating you any differently from everybody else.
Please read the Guidelines (and my email) again.
If you don't like the way Pprune is run, post your views on another website - or start your own.
If you wish to continue posting here, you must abide by decisions even if you disagree with them.
Dave Jackson
1st point: You are entitled to your view. Please refer to the 'Guidelines' post above to see the Pprune view.
2nd point: If Pprune had a full-time monitoring / editorial team, what you suggest might be possible. This entire website is run by people who have other jobs and other demands on their time. We rely upon members to co-operate by abiding by policy decisions even if they disagree with them.
Last edited by Heliport; 29th Jul 2002 at 21:46.
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EMERGENCY AIRWORTHINESS DIRECTIVE
Date July 26, 2002
AD# 2002-15-51
Send to all US owners and operators of Sikorsky Model S76A,B and C Helicopters
"This Emergency Airworthiness Directive (AD) is prompted by the failure of a main rotor blade (blade) due to lightening strike damage. The condition, if not corrected, could result in the loss of control of the helicopter.
The FAA has reveiwed Sikorsky Aircraft Corporation (Sikorsky)
Alert Service Bulletin No. 76-65-55A dated July, 25,2002 (ASB). The ASB sepcifies reviewing the component log cards or, if necessary, other maintenance and operational records or the service istory to determine if a blade has been damaged by a lightening strike, either in flight or on the ground. If the service history cannot be determined, the ASB specifies removing the blade before the next flight. If the records indicate that a blade has been damaged by a lightening strike, the ASB specifies removing it from service before the next flight."
By the looks of it, the FAA thinks it was probably lightening.
LE
Edited for typo LE
Leading Edge has accurately quoted the AD, which can be read in its entirety at: http://av-info.faa.gov/ad/PublishedADs/021551.htm PedalStop, Rotorheads Moderator
Date July 26, 2002
AD# 2002-15-51
Send to all US owners and operators of Sikorsky Model S76A,B and C Helicopters
"This Emergency Airworthiness Directive (AD) is prompted by the failure of a main rotor blade (blade) due to lightening strike damage. The condition, if not corrected, could result in the loss of control of the helicopter.
The FAA has reveiwed Sikorsky Aircraft Corporation (Sikorsky)
Alert Service Bulletin No. 76-65-55A dated July, 25,2002 (ASB). The ASB sepcifies reviewing the component log cards or, if necessary, other maintenance and operational records or the service istory to determine if a blade has been damaged by a lightening strike, either in flight or on the ground. If the service history cannot be determined, the ASB specifies removing the blade before the next flight. If the records indicate that a blade has been damaged by a lightening strike, the ASB specifies removing it from service before the next flight."
By the looks of it, the FAA thinks it was probably lightening.
LE
Edited for typo LE
Leading Edge has accurately quoted the AD, which can be read in its entirety at: http://av-info.faa.gov/ad/PublishedADs/021551.htm PedalStop, Rotorheads Moderator
Last edited by PedalStop; 29th Jul 2002 at 22:35.
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S76Heavy, if you're from the 'Bristow' side of the fence talk to Max and ask his underwear if it should be a land as soon as possible event
This is a metaphoric desciption. No underwear was damaged during the event.
This is a metaphoric desciption. No underwear was damaged during the event.
Last edited by magbreak; 31st Jul 2002 at 16:24.
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I wasn't quite sure whether it was "land as soon as practical" or "ASAP" according to officialdom. Nowadays I would not hesitate to drop it down onto the first available flat surface and have it checked out, but since BF returned to Norwich it might have been an " as practical".
I had heard part of the story, though..
I had heard part of the story, though..