Sikorsky S-92: From Design to Operations
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Tokunbo,
I really haven't slogged much, I think. If I am not mistaken, I have tried to post the facts, against the inuendos from heli-whatshisname.
The facts as they are, and continue to be, in spite of heli-whatshisname, were posted long ago in this thread:
The S-92 transmission has a dual, independant pump system, one shaft lost drive because it wore prematurely. The box had pressure on landing. The crew did as they should. There is an excellent team working to identify the cause of the premature wear, and recommend fixes.
The spline system used on the 92 is similar to that used on many pumps and generator drives, the plastic prevents spline damage from contaminating the box.
I now believe that helicomparitor is a senior Bristow Captain who has thrown his lot in with the 225, and seeks every opportunity to show how right he was to back that old, grandfathered design. He thrills to the 225's lesser payload, lesser range, much smaller cabin, older safety standards, higher purchase price, greater expense to operate, but precisely his cup of tea. Of course, he will now post about 250 lines, painfully recording every prejudiced thought for the pprune world!
I really haven't slogged much, I think. If I am not mistaken, I have tried to post the facts, against the inuendos from heli-whatshisname.
The facts as they are, and continue to be, in spite of heli-whatshisname, were posted long ago in this thread:
The S-92 transmission has a dual, independant pump system, one shaft lost drive because it wore prematurely. The box had pressure on landing. The crew did as they should. There is an excellent team working to identify the cause of the premature wear, and recommend fixes.
The spline system used on the 92 is similar to that used on many pumps and generator drives, the plastic prevents spline damage from contaminating the box.
I now believe that helicomparitor is a senior Bristow Captain who has thrown his lot in with the 225, and seeks every opportunity to show how right he was to back that old, grandfathered design. He thrills to the 225's lesser payload, lesser range, much smaller cabin, older safety standards, higher purchase price, greater expense to operate, but precisely his cup of tea. Of course, he will now post about 250 lines, painfully recording every prejudiced thought for the pprune world!
Nick
I see I now have a new job - I must have been sacked by EC for failing to defend the 225 adequately!
You made multiple posts stating for a fact that I worked for EC. Now suddenly its all different - are the facts you post about the 92 equally transient?
If one pump was still working, how come the pressure was nearly at the bottom of the scale? How come that the flight manual (that you probably wrote!) instructs pilots to land immediately when presented with these indications?
As an olive branch, why don't you PM me with the real answer, then I'll get off your back.
HC
ps that's less than 250 words so wrong again!
I see I now have a new job - I must have been sacked by EC for failing to defend the 225 adequately!
You made multiple posts stating for a fact that I worked for EC. Now suddenly its all different - are the facts you post about the 92 equally transient?
If one pump was still working, how come the pressure was nearly at the bottom of the scale? How come that the flight manual (that you probably wrote!) instructs pilots to land immediately when presented with these indications?
As an olive branch, why don't you PM me with the real answer, then I'll get off your back.
HC
ps that's less than 250 words so wrong again!
What amazes me is that with the invective stripped out there is - as with the previous one on 225 certification - a high technical content in this thread (albeit a single sentence or paragraph in each post).
What I would like to know is why one pump failure caused a drop in pressure from the other pump?
Jim
What I would like to know is why one pump failure caused a drop in pressure from the other pump?
Jim
Bristow being big and British do have a way of cultivating a "We know better attitude" amongst its senior staff. They promote from within...take a cadet, train him in the Bristow way...fly him on the line the Bristow way...and ultimately promote him to management to carry on the Bristow Way. Sometimes that is good...sometimes not so good.
Bell's torgue management system on the 212 wasn't good enough for them....seems too many instances of 212's bleeding Nr during landings and some hard landings were being experienced....rather than admit the young North Sea boys that were being posted to gain command time were not able to adjust to the limited power of the 212 as compared to the Tiger (Super Puma Bristow style)....they elected to remove the torque limiting system. Alas...that also did away with the torque damping ability of the engines...and then the problem became rampant overtorquing. No telling how many trannies, drive shafts, and other moving bits got written off in the attempt to "save" an aircraft from potentially crashing on landing after drooping Nr. They ultimately reversed that decision after the individual mandating it retired. They would never listen to the analysis of the problem which pointed the finger at the real cause.
They also decreed that ditching after having a Generator hot light was the right idea....not withstanding it was determined a grand total of about 25-27 generators were affected by the mis-produced shaft/bearing and once replaced...that problem was solved.
Any discussion of those issues or any others resulted in the "Bristow Knows Best" response.....never mind it was the builder of the aircraft, the component, or a factory training facility that was attempting to take issue with the decision.
I actually heard the statement made..."Bell only builds them...they don't operate them." There was no response to the comment that all of the operators reported problems to the builder thus they gained input from all over the world and all of the operators and not just one source.
They did get it right on the S-61....as compared to the Norwegians....unfortunately they had two spindle failures that were the result of a peculiar way training was done on the aircraft that Bristow did not do. But for years the 61 side of the house were the derelicts and not the new boys.
Since we do not know from whence HC speaks....if in fact as Nick suggests, he may be a Bristow senior Wallah...could it be some of this Bristow mindset is rubbing off on HC.
Is this a case of "better the devil you know...than the devil you don't know" coming into play here.
Bell's torgue management system on the 212 wasn't good enough for them....seems too many instances of 212's bleeding Nr during landings and some hard landings were being experienced....rather than admit the young North Sea boys that were being posted to gain command time were not able to adjust to the limited power of the 212 as compared to the Tiger (Super Puma Bristow style)....they elected to remove the torque limiting system. Alas...that also did away with the torque damping ability of the engines...and then the problem became rampant overtorquing. No telling how many trannies, drive shafts, and other moving bits got written off in the attempt to "save" an aircraft from potentially crashing on landing after drooping Nr. They ultimately reversed that decision after the individual mandating it retired. They would never listen to the analysis of the problem which pointed the finger at the real cause.
They also decreed that ditching after having a Generator hot light was the right idea....not withstanding it was determined a grand total of about 25-27 generators were affected by the mis-produced shaft/bearing and once replaced...that problem was solved.
Any discussion of those issues or any others resulted in the "Bristow Knows Best" response.....never mind it was the builder of the aircraft, the component, or a factory training facility that was attempting to take issue with the decision.
I actually heard the statement made..."Bell only builds them...they don't operate them." There was no response to the comment that all of the operators reported problems to the builder thus they gained input from all over the world and all of the operators and not just one source.
They did get it right on the S-61....as compared to the Norwegians....unfortunately they had two spindle failures that were the result of a peculiar way training was done on the aircraft that Bristow did not do. But for years the 61 side of the house were the derelicts and not the new boys.
Since we do not know from whence HC speaks....if in fact as Nick suggests, he may be a Bristow senior Wallah...could it be some of this Bristow mindset is rubbing off on HC.
Is this a case of "better the devil you know...than the devil you don't know" coming into play here.
Last edited by SASless; 11th Apr 2005 at 12:59.
SASless says:
"Bell's torgue management system on the 212 wasn't good enough for them....seems too many instances of 212's bleeding Nr during landings and some hard landings were being experienced....rather than admit the young North Sea boys that were being posted to gain command time were not able to adjust to the limited power of the 212 as compared to the Tiger "
You're right of course, SASless; it's a brilliant system; why wreck an MGB when you can trash the airframe and its occupants instead? I realise governor damping in hydromechanical AFCUs is an issue, but other manufacturers of the era seem to have coped (on types you have experience on.)
I think you'll find your description of why it was removed is not quite true, but I'll refrain from expanding as it's not a very pleasant subject.
I also think you'll find there is a very experienced test pilot who frequents this forum, who has had adverse experiences and less than favourable opinions with the system in the military.
Going back to the thread though, as JimL says; why did the pressure drop with a single pump failure, or is one merely a standby/back up pump to the main and therefore produces less pressure?
"Bell's torgue management system on the 212 wasn't good enough for them....seems too many instances of 212's bleeding Nr during landings and some hard landings were being experienced....rather than admit the young North Sea boys that were being posted to gain command time were not able to adjust to the limited power of the 212 as compared to the Tiger "
You're right of course, SASless; it's a brilliant system; why wreck an MGB when you can trash the airframe and its occupants instead? I realise governor damping in hydromechanical AFCUs is an issue, but other manufacturers of the era seem to have coped (on types you have experience on.)
I think you'll find your description of why it was removed is not quite true, but I'll refrain from expanding as it's not a very pleasant subject.
I also think you'll find there is a very experienced test pilot who frequents this forum, who has had adverse experiences and less than favourable opinions with the system in the military.
Going back to the thread though, as JimL says; why did the pressure drop with a single pump failure, or is one merely a standby/back up pump to the main and therefore produces less pressure?
Last edited by 212man; 11th Apr 2005 at 15:38.
212man,
Unpleasant topic for sure....but why was the change made...and why was it reversed? Why prior to the change did the aircraft perform reliably over the years and does so again after reverting to the original system? How may overtorques and resulting component changes occurred as a result of altering the original system? It was only Eket that had the change as I recall...and not the other operations...but then the other operations had the old dogs flying and not so many young North Sea guys in general as I recall. Mind you I am not criticizing the young guys...they were excellent in certain aspects of their flying but limited power techinques were something they had to learn.
How many aircraft crashed or were damaged due to loss of rotor rpm prior to the mod....none as I recall? This is the kind of management decision that MBA Advanced degrees should be written about...cost and effect, Law of Unintended Consequences...all that kind of thing.
It would be enlightening to know the "real" story behind that decision...having been the victim of it. Knock on wood I never rang the bell as some did down there....but it was only mere luck that saved me on occasions.
Unpleasant topic for sure....but why was the change made...and why was it reversed? Why prior to the change did the aircraft perform reliably over the years and does so again after reverting to the original system? How may overtorques and resulting component changes occurred as a result of altering the original system? It was only Eket that had the change as I recall...and not the other operations...but then the other operations had the old dogs flying and not so many young North Sea guys in general as I recall. Mind you I am not criticizing the young guys...they were excellent in certain aspects of their flying but limited power techinques were something they had to learn.
How many aircraft crashed or were damaged due to loss of rotor rpm prior to the mod....none as I recall? This is the kind of management decision that MBA Advanced degrees should be written about...cost and effect, Law of Unintended Consequences...all that kind of thing.
It would be enlightening to know the "real" story behind that decision...having been the victim of it. Knock on wood I never rang the bell as some did down there....but it was only mere luck that saved me on occasions.
SASless,
nothing to do with Eket. It was done after an accident in the North Sea in the Eighties. Obviously the Eket machines, beinmg company aircraft, were then fitted too.
The aircraft were not re-modded to the original system; they were modded to the later TB-138/TB-145 state, or HP mod, with a manual beep for the number two engine N2, rather than the TCU doing the matching. At one stage we had all thtree mod states in service in Eket.
nothing to do with Eket. It was done after an accident in the North Sea in the Eighties. Obviously the Eket machines, beinmg company aircraft, were then fitted too.
The aircraft were not re-modded to the original system; they were modded to the later TB-138/TB-145 state, or HP mod, with a manual beep for the number two engine N2, rather than the TCU doing the matching. At one stage we had all thtree mod states in service in Eket.
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SASless and 212man
Can we correspond privately on the Bell 212 torque limiter. I have some knowledge of the system, and would like to discuss it more. Not on this thread, though.
Can we correspond privately on the Bell 212 torque limiter. I have some knowledge of the system, and would like to discuss it more. Not on this thread, though.
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SASless
I often agree with you. But you are not right about the torque limiter issue, not exactly anyway.
At the time, there were no real transfers from Tigers to the 212. The Tiger didn't start until April 1982 and the torque limiting systenm was already bieng trialled at that time. The system made its debut on the old Brent Shuttle contract.
Also, many of the Bristow Cadets turned out to be good pilots and some even progressed to management. They even had some credibility because they had "been there done that" .
HH
I often agree with you. But you are not right about the torque limiter issue, not exactly anyway.
At the time, there were no real transfers from Tigers to the 212. The Tiger didn't start until April 1982 and the torque limiting systenm was already bieng trialled at that time. The system made its debut on the old Brent Shuttle contract.
Also, many of the Bristow Cadets turned out to be good pilots and some even progressed to management. They even had some credibility because they had "been there done that" .
HH
Hippo....
I absolutely agree that some, in fact all but the rare exception, of Bristow's cadets were and are excellent pilots and in the rare exception were great fun to be around. My point is the Nigeria experience was beneficial to them because they got to see a different kind of flying from that on the North Sea.
My statement about the derivation of the mod stems from the mushroom food being provided from on high. Every time the mod was discussed the reaction seemed to be equal to dragging a dental pick over a sore tooth.
It is a world of difference between flying Super Pumas to North Sea standard and to rat killing in Eket on 212's. The surplus power available to you on the Super Puma fosters techniques that are not applicable to the 212. Nothing in that statement in any way is meant to be derrogatory towards the individual....merely suggesting having bags of power is allows for a certain laxness of habit is all. Our young'uns would have been even better served if the old Duri operation had remained available for them to learn external load skills too.
I absolutely agree that some, in fact all but the rare exception, of Bristow's cadets were and are excellent pilots and in the rare exception were great fun to be around. My point is the Nigeria experience was beneficial to them because they got to see a different kind of flying from that on the North Sea.
My statement about the derivation of the mod stems from the mushroom food being provided from on high. Every time the mod was discussed the reaction seemed to be equal to dragging a dental pick over a sore tooth.
It is a world of difference between flying Super Pumas to North Sea standard and to rat killing in Eket on 212's. The surplus power available to you on the Super Puma fosters techniques that are not applicable to the 212. Nothing in that statement in any way is meant to be derrogatory towards the individual....merely suggesting having bags of power is allows for a certain laxness of habit is all. Our young'uns would have been even better served if the old Duri operation had remained available for them to learn external load skills too.
Back on thread?......no more 212 stuff please
This 212/BHL cadet/BHL history lesson is fascinating stuff but perhaps best suited to another thread??
If I can drag this back to the original postings, ignoring the deliberately inflammatory remarks made along the way, can we establish one fact....namely why did the pressure drop by such a large amount given the failure of only one of two MGB pumps.
Nick L, can you please enlighten us?
If I can drag this back to the original postings, ignoring the deliberately inflammatory remarks made along the way, can we establish one fact....namely why did the pressure drop by such a large amount given the failure of only one of two MGB pumps.
Nick L, can you please enlighten us?
Thankyou! It does seem a fundamental question which may have a simple and logical answer
As I said above, perhaps a main and a backup with differing capabilities or, perhaps, two pumps feeding the same system and with a lack of check valves to prevent the path of least resistance being taken by the oil, would seem two logical answers.
As I said above, perhaps a main and a backup with differing capabilities or, perhaps, two pumps feeding the same system and with a lack of check valves to prevent the path of least resistance being taken by the oil, would seem two logical answers.
Last edited by 212man; 12th Apr 2005 at 15:01.
Would hate this to drop off the horizon! Someone must know?
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A/C 7 showed no signs of wear on the splines - and we're over 100 hours even on ours.
There was bound to be a few teething troubles. I was in at the start of the 332 in Aberdeen with BHL in the early 80s. The first couple of Tigers seemed to have a large number of MGB changes. We won't dive too far into the very close call of a spindle nearly letting go a blade on the NW Hutton - well done to that crew.
Lets go easy on the verbal sparring and wait for the facts to come out along with the fix which will no doubt appear very soon.
There was bound to be a few teething troubles. I was in at the start of the 332 in Aberdeen with BHL in the early 80s. The first couple of Tigers seemed to have a large number of MGB changes. We won't dive too far into the very close call of a spindle nearly letting go a blade on the NW Hutton - well done to that crew.
Lets go easy on the verbal sparring and wait for the facts to come out along with the fix which will no doubt appear very soon.
Robin Duff? Wee sort of man...that licks his whisky off packing crates and spits splinters?
I remember that day on the NW Hutton very well.
Scariest thing I had (have) ever seen. Nice work by Chris and Neil to get it down in one piece.
Always something new to learn everyday in the helicopter business.
Scariest thing I had (have) ever seen. Nice work by Chris and Neil to get it down in one piece.
Always something new to learn everyday in the helicopter business.
Iconoclast
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30 minute run dry.
On most transmissions that are certified for 30 running with no oil in the sump or loss of the pump(s) most of the individual gears in the transmission have hollow shafts which are filled with some absorbent material. When the transmission starts turning some oil is absorbed by this material and stays there while the transmission is turning. When the transmission stops most of this absorbed oil will drain back into the sump. Each gear that has this material installed has small holes that allow for centrifugal slinging of this retained oil into the respective gear meshes.
The EH 101 not only has this facility it has two separate oil sumps each with it’s own pump to cater to the loss of a pump or battle damage to one of the sumps. If both sumps are compromised the transmission can be run for 30 minutes.
If this has already been addressed please forgive me.
The EH 101 not only has this facility it has two separate oil sumps each with it’s own pump to cater to the loss of a pump or battle damage to one of the sumps. If both sumps are compromised the transmission can be run for 30 minutes.
If this has already been addressed please forgive me.