How Important Is Crashworthiness?
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Weights
The S92 AUM is 11,861Kgs and Empty wt of 7,212kgs giving a disposable of 4,649kgs.
The EC225 AUM is 10,400kgs and Empty wt of 5,135kgs giving a disposable of 5135kgs.
Going off track
Looking at the realy high AUM of each aircraft does this not restrict them on some rigs because of the deck weight allowable.
I realise this not a problem outbound as fuel will be burnt.
But if you had a headwind going home, had a full load and needed as much fuel as possible.
No doubt some kind current pilot will advise me.
My thoughts. Both of the aircraft look really superb and I am sure will operate equally as well on the North Sea.
The EC225 AUM is 10,400kgs and Empty wt of 5,135kgs giving a disposable of 5135kgs.
Going off track
Looking at the realy high AUM of each aircraft does this not restrict them on some rigs because of the deck weight allowable.
I realise this not a problem outbound as fuel will be burnt.
But if you had a headwind going home, had a full load and needed as much fuel as possible.
No doubt some kind current pilot will advise me.
My thoughts. Both of the aircraft look really superb and I am sure will operate equally as well on the North Sea.
Last edited by jbrereton; 12th Apr 2005 at 17:29.
jbrereton
Deck limits - that is a good question that has fortunately been thought of and solved already. Independant studies were commissioned by both aircraft's manufacturers that showed that the peak deck loading following a reasonably forseeable event (engine failure) was no greater than that created by an S61 under the same circumstances, due to the improved energy absorbtion of the undercarriage and the increased engine power. No doubt a deck could be demolished by one of the new breed, but so could it be by a runaway S61 under extreme circumstances.
Regarding your weight figures, sorry you are way off the mark for the 225 - max wt is 11000kg, empty weight in N Sea fit is about 6500kg. I think you will find that the S92 has a very similar disposable in the same configuration (with the strengthened floor). I believe the 92s operating in the North Sea have very slightly less disposable than my proposal for the 225 above, but then no 225s have actually been delivered yet in N Sea fit so the weight is the manufacturer's guess! All in all nothing in it.
But hasn't most of this thread been off topic? Its called "How important is crashworthiness"
The answer is simple - its completely unimportant until you crash!
So would you rather have an aircraft that is pleasant to fly, very tolerant of pilot error, proven to be well designed regarding redundancy of systems, mechanically robust and with proven system reliabilty, but one that when the worst day does comes and the ground arrives unexpectedy, is less protective than it could be?
Or would you rather fly the aircraft that is the opposite to the above (to save typing!)
Personally I would rather be in the former, and you can see where this post is leading.........but I won't say it because I promised myself I would be on best behaviour today!
HC
Deck limits - that is a good question that has fortunately been thought of and solved already. Independant studies were commissioned by both aircraft's manufacturers that showed that the peak deck loading following a reasonably forseeable event (engine failure) was no greater than that created by an S61 under the same circumstances, due to the improved energy absorbtion of the undercarriage and the increased engine power. No doubt a deck could be demolished by one of the new breed, but so could it be by a runaway S61 under extreme circumstances.
Regarding your weight figures, sorry you are way off the mark for the 225 - max wt is 11000kg, empty weight in N Sea fit is about 6500kg. I think you will find that the S92 has a very similar disposable in the same configuration (with the strengthened floor). I believe the 92s operating in the North Sea have very slightly less disposable than my proposal for the 225 above, but then no 225s have actually been delivered yet in N Sea fit so the weight is the manufacturer's guess! All in all nothing in it.
But hasn't most of this thread been off topic? Its called "How important is crashworthiness"
The answer is simple - its completely unimportant until you crash!
So would you rather have an aircraft that is pleasant to fly, very tolerant of pilot error, proven to be well designed regarding redundancy of systems, mechanically robust and with proven system reliabilty, but one that when the worst day does comes and the ground arrives unexpectedy, is less protective than it could be?
Or would you rather fly the aircraft that is the opposite to the above (to save typing!)
Personally I would rather be in the former, and you can see where this post is leading.........but I won't say it because I promised myself I would be on best behaviour today!
HC
Last edited by HeliComparator; 12th Apr 2005 at 18:37.
Ah...but if you can have the fine ride and the other benefits that is where you would go right HC especially at a 25% discount....which if the bean counters running the outfit have the final say...that is what will happen. Of course the trade-in value of old Mark II's and Tigers will be worth more to EC than to Igor thus that must be factored into the decision.
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HeliComparator
Yes thanks for that I obviously looked at an old spec for the EC225.
What would I like for flying. Well I want an aircraft that has comfortable crew seats and systems that would prevent me having to crash i.e run dry Gearbox, back up electrical system.
May sound weird, but to me when I was flying comfort was everything especially when doing 6-8 hour flying duties.
What would I like for flying. Well I want an aircraft that has comfortable crew seats and systems that would prevent me having to crash i.e run dry Gearbox, back up electrical system.
May sound weird, but to me when I was flying comfort was everything especially when doing 6-8 hour flying duties.
if you can have the fine ride
jbrereton - I couldn't agree more. We are all going to die sometime but I would prefer to be comfortable in the mean time!
Have you ever looked around your aircraft's cockpit and wondered what would happen to your head when you crashed (helmet-wearers excepted). The aircraft I currently fly all have horrendous sharp and solid bits that stick out close to my head. If it was a car, it would have been banned long ago (or the manufacturer sued to oblivion).
So why do we need fantastically crashworthy fuel systems and stroking seats etc when my head is going to be mince (more than it is already, before you reach for the keyboard). Why can't manufacturers put a bit of effort into making the cockpit as crash-friendly to my head as Henry Ford has in my car costing one thousandth of the price
HC
Last edited by HeliComparator; 12th Apr 2005 at 20:01.
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HeliComparator
Yes you are quite right about the pokey out bits. The only option would be for pilots to all wear helmets as the military do.
This would cost very little to achieve and you would be as popular as Hitler to the Allies in WW2.
Lets face it the cost is prohibitive to get rid of the sticky out bits.
Your car may be safe for you to rattle around in on the inside but do you have run flat tyres to cut down the possibility of this happening. I'll bet not.
Well the helicopters of now do have this capability so be happy!
This would cost very little to achieve and you would be as popular as Hitler to the Allies in WW2.
Lets face it the cost is prohibitive to get rid of the sticky out bits.
Your car may be safe for you to rattle around in on the inside but do you have run flat tyres to cut down the possibility of this happening. I'll bet not.
Well the helicopters of now do have this capability so be happy!
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jbrereton,
The AUM as given by brochures can be widely varient, and depends on the actual equipment selected, and the features of the aircraft. For example, the 225 would have difficulty being approved to carry passengers in many countries unless fitted with its "optional" crashworthy floors, stroking seats and modern seat belts.
These safety features are negociable to helicomparitor, I guess, but are required in modern FAR/JAR, and can only be circumvented by grandfathering the certification (a failure of EC to make the Mark II they had planned, reportedly when the French authorities told them they would not grandfather a new fuselage, so the cost of the Mark III went up too much and it was dropped.) Operationally, different authorities get involved, as does local politics (imagine helicompartior's viewpoint if the EC 225 had the greater crashworthiness, considering how purple he gets at seat adjustability!)
These safety requirements add about 600Kg to the equipped empty weight, we are told by a customer who didn't chose the 225 (in fact, that customer was told by the EC salesman that the crashworthy seats and floor had not yet been designed.)
Given that extra needed weight, the 225's performance is about at par with the 92, or even shy. Independant studies by customers (I have two on my hard drive, done by folks who bought S-92) generally show between 2 to 4 passenger advantage for the S-92.
helicomparitor continues his slurs, with snide, inaccurate comments about comfort. He seems to imply vibration and such. I think I recall S-92 mech telling us that passengers were thrilled with the comfort in the S-92. I am sure they appreciated the stand-up headroom, and the fact that they didn't have to walk aft on their knees, like they have to in the tiny cabin of the 225. Also, the seat room of the 92 is several inches more than the 225, because the cabin is so very much bigger.
Remember that the S-92 is designed to crash standards about TWICE as strong as the 225, in a whole new league. It is safer, and more comfortable. Yea, if you want comfort, maybe you CAN get safety, too.
rotorpower,
It is clear that helicomparitor has sold his soul, when he tries to equate safety for his passengers with his adjustability on his seat. Such crackpot comparisons have no place among professionals, except in EC-land.
The AUM as given by brochures can be widely varient, and depends on the actual equipment selected, and the features of the aircraft. For example, the 225 would have difficulty being approved to carry passengers in many countries unless fitted with its "optional" crashworthy floors, stroking seats and modern seat belts.
These safety features are negociable to helicomparitor, I guess, but are required in modern FAR/JAR, and can only be circumvented by grandfathering the certification (a failure of EC to make the Mark II they had planned, reportedly when the French authorities told them they would not grandfather a new fuselage, so the cost of the Mark III went up too much and it was dropped.) Operationally, different authorities get involved, as does local politics (imagine helicompartior's viewpoint if the EC 225 had the greater crashworthiness, considering how purple he gets at seat adjustability!)
These safety requirements add about 600Kg to the equipped empty weight, we are told by a customer who didn't chose the 225 (in fact, that customer was told by the EC salesman that the crashworthy seats and floor had not yet been designed.)
Given that extra needed weight, the 225's performance is about at par with the 92, or even shy. Independant studies by customers (I have two on my hard drive, done by folks who bought S-92) generally show between 2 to 4 passenger advantage for the S-92.
helicomparitor continues his slurs, with snide, inaccurate comments about comfort. He seems to imply vibration and such. I think I recall S-92 mech telling us that passengers were thrilled with the comfort in the S-92. I am sure they appreciated the stand-up headroom, and the fact that they didn't have to walk aft on their knees, like they have to in the tiny cabin of the 225. Also, the seat room of the 92 is several inches more than the 225, because the cabin is so very much bigger.
Remember that the S-92 is designed to crash standards about TWICE as strong as the 225, in a whole new league. It is safer, and more comfortable. Yea, if you want comfort, maybe you CAN get safety, too.
rotorpower,
It is clear that helicomparitor has sold his soul, when he tries to equate safety for his passengers with his adjustability on his seat. Such crackpot comparisons have no place among professionals, except in EC-land.
Nick
I'll avoid commenting on the inaccuracies of your post that I have already dealt with (probably many times!) for the sake of the long-suffering readers.
When I was talking about comfort/adjustability versus safety, I wonder if it was only you that didn't realise I was talking about the pilot's seats. Passenger seats are rarely adjustable in my experience, and certainly not on the 92.
You do post a lot about the opposition's aircraft's faults. At election time, these days even the politicians seem to have finally learned that the electorate (=customers) are not impressed by denigrating the opposition.
I also can't help commenting on how you like to remind us about the stand-up cabin headroom in the 92. In EC's aircraft I find most of our passengers prefer to sit down - but in the 92 you could ditch the seats altogether and have them stand all the way - think of the extra payload that would give!
No, maybe you should leave the seats in for any old or infirm passengers. But with that extra 4 inches cabin length over the 225 divided into the 7 rows of seats, they do certainly gain more than half an inch of leg room, which will surely put an end to the offshore workers DVT syndrome! See - I don't always criticise the 92
A couple of thoughts before bed because I'm feeling mean now.... you said
Yes, if you fixed the vibration problem and redesigned the transmission lube system so that it had some redundancy and lasted more than 200hrs from new
You also said:
From what I have recently learnt about the 92's transmission system, I would say this is just as well.
'night
HC
I'll avoid commenting on the inaccuracies of your post that I have already dealt with (probably many times!) for the sake of the long-suffering readers.
When I was talking about comfort/adjustability versus safety, I wonder if it was only you that didn't realise I was talking about the pilot's seats. Passenger seats are rarely adjustable in my experience, and certainly not on the 92.
You do post a lot about the opposition's aircraft's faults. At election time, these days even the politicians seem to have finally learned that the electorate (=customers) are not impressed by denigrating the opposition.
I also can't help commenting on how you like to remind us about the stand-up cabin headroom in the 92. In EC's aircraft I find most of our passengers prefer to sit down - but in the 92 you could ditch the seats altogether and have them stand all the way - think of the extra payload that would give!
No, maybe you should leave the seats in for any old or infirm passengers. But with that extra 4 inches cabin length over the 225 divided into the 7 rows of seats, they do certainly gain more than half an inch of leg room, which will surely put an end to the offshore workers DVT syndrome! See - I don't always criticise the 92
A couple of thoughts before bed because I'm feeling mean now.... you said
Yea, if you want comfort, maybe you CAN get safety, too.
You also said:
Remember that the S-92 is designed to crash standards about TWICE as strong as the 225, in a whole new league
'night
HC
Last edited by HeliComparator; 12th Apr 2005 at 23:13.
Having worked on AS 332 L,L1 and L2 and S76 ,S61 and S70 Blackhawks for awhile now and having seen the remains of all models after crashes , I know which a/c I would sooner be in (none of them) but the Sikorsky product is a hell of a lot stronger than the Eurocrap (I don't mind super pumas unfortunatly there build by the french), the EC 225 is basicly an L2 airframe which is an L1 airframe with a plug in it ,and as another input said pity the airframe is a "sardine can" I unfortunatly haven't seen a S92 up close yet but all the info i've seen and other Sikorsky a/c i've worked on would indicate the 92 is far ahead of the 225 in crashworthiness and servivability and I won't even go into the the thing the French call a fuel system in the Puma series compared to any US build a/c, only the french could certify a fuel system were the fuel lines are just clamped up with simple hose clamps insted of swageing fitting onto hoses!
I shouldn't say any more.....but I will ;-)
NickL
You say that two customer studies show that the S92 can carry between 2-4 pax more. One word of caution, I suspect that the studies were done before ECF raised the AUM to 11,000kgs? The data I have for identical offshore specced machine (except the S92 weight is for 5 screens - but both include crashworthy floors, seats, etc) gives an empty AUM of 17,000 lbs for the S92 and 6,400kgs (14,100 lbs) for the 225. As previously stated this gives the 225 about 1000 lbs extra payload, unless ECF were telling porkies??
HC
You talked about system redundancy being important. I agree, however the S92 must win in this contest: Three hydraulic systems, three sources of generated power, two tail rotor control paths plus an "NFG" type spring, dual flight control paths before the mixer, four failures before all AP functionality is lost.
You mention known in service reliability as a plus. Again I agree, however the EC225 has less in service experience that the S92 i.e. it has none. The L2 of course does, but Bristow know very little about the aircraft. I know Norsk have experience...but wait a minute, haven't they now got two S92s??
So what does the L2 in service experience tell us....that the LH accessory module is a disaster. That the Puma airframe still frequently develops cracks in the primary structure - but no worry there, because they've now increased the MAUM and cut bigger holes in it
Oh, an experienced operator will also point out that they have experienced MGB overtorques because the crew slavishly follow the FLI and don't think about any other parameters.
Cockpit size and "sticky out bits" has been mentioned....ooopps the S92 wins again. Talking of cockpit, didn't Bristows have one of their pilots get injured after he fell off backwards climbing into the only L2 you (sorry - they) have. Access to the cockpit, and cabin for that matter, is dreadful. Give me an airstair door any day.
Surely the 225 must be better at something. Yup, vibration levels are the best I have ever experienced. The S92 vibration is OK but could and should be better, more of a constant rumble rather than the bounce that most of us are used to on older designs.
However, if we're talking overall comfort levels, etc despite the vibration I still believe the S92 wins. The cabin is much better, with much more room and seats arranged so that you don't have to play "kneesy" with the guy sitting opposite you. The NOISE LEVEL (shouting deliberately here!) in the 225 is nothing to write home about, especially in the cockpit. The S92 is the quietest I have experienced. You can also get an aircon unit that actually works with the 92.
At the end of the day the perfect helicopter hasn't been built yet.......I'm sure we all live in hope
You say that two customer studies show that the S92 can carry between 2-4 pax more. One word of caution, I suspect that the studies were done before ECF raised the AUM to 11,000kgs? The data I have for identical offshore specced machine (except the S92 weight is for 5 screens - but both include crashworthy floors, seats, etc) gives an empty AUM of 17,000 lbs for the S92 and 6,400kgs (14,100 lbs) for the 225. As previously stated this gives the 225 about 1000 lbs extra payload, unless ECF were telling porkies??
HC
You talked about system redundancy being important. I agree, however the S92 must win in this contest: Three hydraulic systems, three sources of generated power, two tail rotor control paths plus an "NFG" type spring, dual flight control paths before the mixer, four failures before all AP functionality is lost.
You mention known in service reliability as a plus. Again I agree, however the EC225 has less in service experience that the S92 i.e. it has none. The L2 of course does, but Bristow know very little about the aircraft. I know Norsk have experience...but wait a minute, haven't they now got two S92s??
So what does the L2 in service experience tell us....that the LH accessory module is a disaster. That the Puma airframe still frequently develops cracks in the primary structure - but no worry there, because they've now increased the MAUM and cut bigger holes in it
Oh, an experienced operator will also point out that they have experienced MGB overtorques because the crew slavishly follow the FLI and don't think about any other parameters.
Cockpit size and "sticky out bits" has been mentioned....ooopps the S92 wins again. Talking of cockpit, didn't Bristows have one of their pilots get injured after he fell off backwards climbing into the only L2 you (sorry - they) have. Access to the cockpit, and cabin for that matter, is dreadful. Give me an airstair door any day.
Surely the 225 must be better at something. Yup, vibration levels are the best I have ever experienced. The S92 vibration is OK but could and should be better, more of a constant rumble rather than the bounce that most of us are used to on older designs.
However, if we're talking overall comfort levels, etc despite the vibration I still believe the S92 wins. The cabin is much better, with much more room and seats arranged so that you don't have to play "kneesy" with the guy sitting opposite you. The NOISE LEVEL (shouting deliberately here!) in the 225 is nothing to write home about, especially in the cockpit. The S92 is the quietest I have experienced. You can also get an aircon unit that actually works with the 92.
At the end of the day the perfect helicopter hasn't been built yet.......I'm sure we all live in hope
Back to the original question. How important is a crashworthy design? This translates to, what will an operator pay for crashworthiness? What is the price of a crashworthy design? If one follows the design trail of the S-92, it began as a Super Hawk with a gross weight near 22,000 lbs and an empty weight of 12,000. As Sikorsky shifted requirements emphasizing flaw tolerance and crashworthy attributes the gross and empty weight grew to what we have today. GW= 26,150 Empty weight = 15,900. If Nick is up he may want to comment on the weight growth of the Main Rotor Hub as a function of moving away from the S-70/S-76 spindle design to the present flaw/damage fault design on the S-92. I believe that the S-92 hub is 200 lbs heavier than the S-70- hub. This will provides a representative example.
Variable Load
The 92 certainly has good redundancy in many areas, but let's look at the points you mentioned:
3 hydraulic systems - so does each jack etc have 3 cylinders? or does it just have 3 pumps, same as the 225
3 sources of generated power: same as the 225 in N Sea fit
2 tail rotor control paths: True, the 92 has double cables whereas the 225 only has single (plus the NFG spring equivalent), however how many Super Pumas have had tail rotor cable failures - none that I know of, whereas its a bit of an issue with earlier Sikorsky products (due to the relative ease of making maintenance errors in this area). However the 92's control run is only duplex in some places...chain is as strong as its weakest link etc
Dual flight control paths before the mixer - I haven't heard that one before (unless you mean the captains and co-pilot's controls!) but how often has there been a control disconnect in that area in any helicopter other than as a result of being shot at?
4 Lanes of autopilot - same on the 225.
However we have discovered in another thread that probably the most critical area of the aircraft seems to cease functioning with a single-point and reasonably predictable failure due, rumour has it, to poor system design, whereas the L/L2/225 has a much more robust system. How many other poor system design issues are lurking that we have yet to find?
LH accessory module - yes a disgrace on the L2, but I am hopeful that a final fix, just out, will sort out that problem at last.
Cracking on the L/L2, yes there have been cracks, but on airframes with many thousands of hours, not less than 200 as is the case with the 92. I do think this is a valid concern for the 225 however, as the gross weight has gone up massively. Only time will tell.
Cockpit access: The L/L2/225 has a high step to get in and is slightly awkward. The airstair door is great but I found having to get into the 92's cockpit by squeezing in through the jumpseat area to be worse. Be careful with the airstair door however, apparently its not HLO-proof!
Cabin noise: you don't know what that is like for the 225 because you have never been in one with the 85db trim fitted (neither have I for that matter!) but 85db sounds fairly quiet to me. Do you know what the 92's cabin noise level is (actual, not brochure figures)?
Anyway, these aircraft are pretty close really despite my trying to score points from Nick - that's why it took you so long to decide which to buy. I am sure you will enjoy your new toys and if I were making the choice for an aircraft to operate in your location, the fact that the aircon actually works on the 92 would be a big factor. With such short sector lengths, performance could hardly have been an issue. When is the delivery scheduled?
In fact I think the S92 is wonderful really - (well you never know when I might need to come grovelling down to the land of jungle and polo pitches for a job!)
HC
The 92 certainly has good redundancy in many areas, but let's look at the points you mentioned:
3 hydraulic systems - so does each jack etc have 3 cylinders? or does it just have 3 pumps, same as the 225
3 sources of generated power: same as the 225 in N Sea fit
2 tail rotor control paths: True, the 92 has double cables whereas the 225 only has single (plus the NFG spring equivalent), however how many Super Pumas have had tail rotor cable failures - none that I know of, whereas its a bit of an issue with earlier Sikorsky products (due to the relative ease of making maintenance errors in this area). However the 92's control run is only duplex in some places...chain is as strong as its weakest link etc
Dual flight control paths before the mixer - I haven't heard that one before (unless you mean the captains and co-pilot's controls!) but how often has there been a control disconnect in that area in any helicopter other than as a result of being shot at?
4 Lanes of autopilot - same on the 225.
However we have discovered in another thread that probably the most critical area of the aircraft seems to cease functioning with a single-point and reasonably predictable failure due, rumour has it, to poor system design, whereas the L/L2/225 has a much more robust system. How many other poor system design issues are lurking that we have yet to find?
LH accessory module - yes a disgrace on the L2, but I am hopeful that a final fix, just out, will sort out that problem at last.
Cracking on the L/L2, yes there have been cracks, but on airframes with many thousands of hours, not less than 200 as is the case with the 92. I do think this is a valid concern for the 225 however, as the gross weight has gone up massively. Only time will tell.
Cockpit access: The L/L2/225 has a high step to get in and is slightly awkward. The airstair door is great but I found having to get into the 92's cockpit by squeezing in through the jumpseat area to be worse. Be careful with the airstair door however, apparently its not HLO-proof!
Cabin noise: you don't know what that is like for the 225 because you have never been in one with the 85db trim fitted (neither have I for that matter!) but 85db sounds fairly quiet to me. Do you know what the 92's cabin noise level is (actual, not brochure figures)?
Anyway, these aircraft are pretty close really despite my trying to score points from Nick - that's why it took you so long to decide which to buy. I am sure you will enjoy your new toys and if I were making the choice for an aircraft to operate in your location, the fact that the aircon actually works on the 92 would be a big factor. With such short sector lengths, performance could hardly have been an issue. When is the delivery scheduled?
In fact I think the S92 is wonderful really - (well you never know when I might need to come grovelling down to the land of jungle and polo pitches for a job!)
HC
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variable load,
The equipped empty weight of the 92, as delivered to offshore operators (in their precise equipment) is about 16, 450 lbs. I think they add perhaps 50 lbs of extras, so I believe the fully provisioned aircraft sits on the ramp, all inclusive, at 16,500 lbs. This might be 500 lbs better than your figures, depending on how you account for crew. Can you crunch that in and see what it does. Does anyone have a ramp weight on a 225? I doubt their brochures, frankly, as it seems the excellent payloads they publish evaporate when exposed to salt air. Honestly, I can't recall when the rise in MGW for the 225 occurred (I know it was right after they lost the first 10 sales to the 92!) Anyone know what that increase does to their component lives and cost to operate?
Thanks for your review of the relative features of the two. Seems right.
I also note the cost to operate, and the cost to buy as significantly higher for the 225. If we use helicomparitor's 2 million dollars greater purchase price, that works out to about $32,000 per month greater cost just to pay the loan on the difference. The operating cost is probably about $250 per hour lower for the 92 (and set to a fixed power by the hour contract) so for a 100 hour month, that is $25,000 more for the 225. Total monthly charge would be perhaps $57,000 more for the 225. At 100 hours flight time, and 19 pax, that would be about $0.20 per passenger mile more expensive! That is a big number (do the passenger-seat-mile calculation math on your last airline ticket to check)
Jackcarson, the flaw tolerance is no small potatoes, it costs perhaps 400 lbs total aircraft weight, but it prevents cracks from forming on rotating parts, at a big safety leap. It also makes the components very close to unlimited life, so the cost to operate drops a lot.
The equipped empty weight of the 92, as delivered to offshore operators (in their precise equipment) is about 16, 450 lbs. I think they add perhaps 50 lbs of extras, so I believe the fully provisioned aircraft sits on the ramp, all inclusive, at 16,500 lbs. This might be 500 lbs better than your figures, depending on how you account for crew. Can you crunch that in and see what it does. Does anyone have a ramp weight on a 225? I doubt their brochures, frankly, as it seems the excellent payloads they publish evaporate when exposed to salt air. Honestly, I can't recall when the rise in MGW for the 225 occurred (I know it was right after they lost the first 10 sales to the 92!) Anyone know what that increase does to their component lives and cost to operate?
Thanks for your review of the relative features of the two. Seems right.
I also note the cost to operate, and the cost to buy as significantly higher for the 225. If we use helicomparitor's 2 million dollars greater purchase price, that works out to about $32,000 per month greater cost just to pay the loan on the difference. The operating cost is probably about $250 per hour lower for the 92 (and set to a fixed power by the hour contract) so for a 100 hour month, that is $25,000 more for the 225. Total monthly charge would be perhaps $57,000 more for the 225. At 100 hours flight time, and 19 pax, that would be about $0.20 per passenger mile more expensive! That is a big number (do the passenger-seat-mile calculation math on your last airline ticket to check)
Jackcarson, the flaw tolerance is no small potatoes, it costs perhaps 400 lbs total aircraft weight, but it prevents cracks from forming on rotating parts, at a big safety leap. It also makes the components very close to unlimited life, so the cost to operate drops a lot.
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Well I did not want to get the slogging match started, but it did. A few points to Lappos, overall, for staying slightly close to the bounds of reason but still, facts, gentlemen, facts.
So far, we have found this:
Crashworthiness - Safety credit to the Sikorsky, with capitulation from EC on that point (and please, helicomparitor, the idea that pilot comfort somehow more important than better safety features - don't tell that to my wife and children!)
Performance - perhaps a wash, but some thoughts that a slight advantage goes to the 225.
Comfort - seems to be in favor of the 92 by seat size and cabin height, with some advantage to the 225 for vibration (only HC says the 92 is objectionable, though).
Cost - some info that the 92 has advantage here, but need another source (sorry Lappos!)
Value of crashworthiness - still not precisely defined, of course. General agreement that safety is important, except from HC, who seems to believe it is quite right now, as is.
Can someone fill in the blanks on cost, and also, I still do not know how a seat makes you more or less safe.
So far, we have found this:
Crashworthiness - Safety credit to the Sikorsky, with capitulation from EC on that point (and please, helicomparitor, the idea that pilot comfort somehow more important than better safety features - don't tell that to my wife and children!)
Performance - perhaps a wash, but some thoughts that a slight advantage goes to the 225.
Comfort - seems to be in favor of the 92 by seat size and cabin height, with some advantage to the 225 for vibration (only HC says the 92 is objectionable, though).
Cost - some info that the 92 has advantage here, but need another source (sorry Lappos!)
Value of crashworthiness - still not precisely defined, of course. General agreement that safety is important, except from HC, who seems to believe it is quite right now, as is.
Can someone fill in the blanks on cost, and also, I still do not know how a seat makes you more or less safe.
rotorpower
Nick is right about the costs so long as the dollar remains weak.
You are muddying things by using "crashworthiness" and "safety" synonymously. Crashworthiness is all about minimising injury when you crash. Safety is about minimising injury, but the best way to do that is not to crash in the first place. Thus crashworthiness is a small subset of safety.
I stick to my point about comfort v crashworthiness. I was not saying that I am happy with the way things are - I thought my point about the cockpit environment made that quite clear, and anything done to improve crashworthiness has to be a good idea provided something else is not compromised excessively.
But take the case of crashworthy pilot seats. At the moment, these compromise pilot comfort.
Lets say you are the boss who is trying to decide what to do for the best regarding new aircraft/equipment. You know that your pilots are always having problems with bad backs, this is unpleasant for them, bad for you (they are always sick) and some even lose their licences/livelihoods as a result. They are getting more litigious and will sue you under HSE rules because you failed to provide the seating designed to the best orthopaedic standards under the duty of care to your employees.
So are you really going to go out and buy less comfortable seats when you know that will exaccerbate the problem, given that no pilots have been killed/badly injured in accidents where crashworthy seating would have made any difference in your company's living memory.
Personally, as I said before, I would rather spend 700 hrs a year in the best comfort available and take the chance that I don't need the seat in a crash. There is even a flight safety issue here - pilots in discomfort get more fatigued and so make more mistakes than their comfortable counterparts (provided they stay awake!)
HC
Nick is right about the costs so long as the dollar remains weak.
You are muddying things by using "crashworthiness" and "safety" synonymously. Crashworthiness is all about minimising injury when you crash. Safety is about minimising injury, but the best way to do that is not to crash in the first place. Thus crashworthiness is a small subset of safety.
I stick to my point about comfort v crashworthiness. I was not saying that I am happy with the way things are - I thought my point about the cockpit environment made that quite clear, and anything done to improve crashworthiness has to be a good idea provided something else is not compromised excessively.
But take the case of crashworthy pilot seats. At the moment, these compromise pilot comfort.
Lets say you are the boss who is trying to decide what to do for the best regarding new aircraft/equipment. You know that your pilots are always having problems with bad backs, this is unpleasant for them, bad for you (they are always sick) and some even lose their licences/livelihoods as a result. They are getting more litigious and will sue you under HSE rules because you failed to provide the seating designed to the best orthopaedic standards under the duty of care to your employees.
So are you really going to go out and buy less comfortable seats when you know that will exaccerbate the problem, given that no pilots have been killed/badly injured in accidents where crashworthy seating would have made any difference in your company's living memory.
Personally, as I said before, I would rather spend 700 hrs a year in the best comfort available and take the chance that I don't need the seat in a crash. There is even a flight safety issue here - pilots in discomfort get more fatigued and so make more mistakes than their comfortable counterparts (provided they stay awake!)
HC
Last edited by HeliComparator; 13th Apr 2005 at 11:08.
"Honestly, I can't recall when the rise in MGW for the 225 occurred (I know it was right after they lost the first 10 sales to the 92!) Anyone know what that increase does to their component lives and cost to operate?"
Probably much the same effect it will have on the S-92 when its weight increases in the future!
Surely no design enters service at the final intended weight and it is that weight upon which most factors (such as componant life etc) are predicated?
Probably much the same effect it will have on the S-92 when its weight increases in the future!
Surely no design enters service at the final intended weight and it is that weight upon which most factors (such as componant life etc) are predicated?
HC
Taking some of your points and adding my understanding:
Hydraulic jacks utilise 2 hydraulic systems, however each of the three systems are capable of backing up the other.
You say 225 has 3 generated sources of power ?
Autopilot - I believe the 225 still has a single failure mode that will remove the autopilot - the AP hydraulics?
The cracking experienced on the Norsk S92 is in non-load bearing secondary structures. I'm sure there'll be a fix real quick. The Super Puma frame cracks have been in evidence for decades and usually requires a frame change...not quite the same thing really
Airstair door....great idea, but I agree should have been done better. Good job we don't let HLO's touch anything!
My noise comments were based purely on a flight in a commercial S92. I thought the 225 cockpit was still very noisy, but better than an L2.
Crashworthy crew seats vs comfort. I agree with you on this one, comfort shouldn't really be compromised. The two are not incompatible. I also think both manufacturers should be selling their aircraft equipped with ANR headsets as standard.
Finally, thanks for your various inputs over the past 9 months or so....it's been an interesting journey.
I'm sure you'll enjoy flying the 225 if you're given the chance. I think it's a fantastic pilot's aircraft
Nick
I'll stand by my ramp weight for the S92 (excluding crew) of 17,000 lbs. Have a chat to your sales guys (JD) if you doubt me. The figure for the 225 was as quoted by ECF given the same spec.
Up to now I haven't mentioned costs as I see this as being commercially confidential information. Your summary is about right - although the operating cost gap is bigger, but all costs are totally dependant upon exchange rates.
rotorpower
The crashworthy seat protects the occupant in a number of ways. High vertical forces are absorbed by the seat (in a controlled way i.e. it doesn't simply collapse) rather than your spine, etc. High horizontal forces will not result in the seat being ripped up away from the floor mountings, etc, etc.
I hope this quick and dirty response helps you understand how a seat makes you more or less safe?
VL
Taking some of your points and adding my understanding:
Hydraulic jacks utilise 2 hydraulic systems, however each of the three systems are capable of backing up the other.
You say 225 has 3 generated sources of power ?
Autopilot - I believe the 225 still has a single failure mode that will remove the autopilot - the AP hydraulics?
The cracking experienced on the Norsk S92 is in non-load bearing secondary structures. I'm sure there'll be a fix real quick. The Super Puma frame cracks have been in evidence for decades and usually requires a frame change...not quite the same thing really
Airstair door....great idea, but I agree should have been done better. Good job we don't let HLO's touch anything!
My noise comments were based purely on a flight in a commercial S92. I thought the 225 cockpit was still very noisy, but better than an L2.
Crashworthy crew seats vs comfort. I agree with you on this one, comfort shouldn't really be compromised. The two are not incompatible. I also think both manufacturers should be selling their aircraft equipped with ANR headsets as standard.
Finally, thanks for your various inputs over the past 9 months or so....it's been an interesting journey.
I'm sure you'll enjoy flying the 225 if you're given the chance. I think it's a fantastic pilot's aircraft
Nick
I'll stand by my ramp weight for the S92 (excluding crew) of 17,000 lbs. Have a chat to your sales guys (JD) if you doubt me. The figure for the 225 was as quoted by ECF given the same spec.
Up to now I haven't mentioned costs as I see this as being commercially confidential information. Your summary is about right - although the operating cost gap is bigger, but all costs are totally dependant upon exchange rates.
rotorpower
The crashworthy seat protects the occupant in a number of ways. High vertical forces are absorbed by the seat (in a controlled way i.e. it doesn't simply collapse) rather than your spine, etc. High horizontal forces will not result in the seat being ripped up away from the floor mountings, etc, etc.
I hope this quick and dirty response helps you understand how a seat makes you more or less safe?
VL
VL
OK, not sure how the 92 hydraulic system hangs together, sounds like there are 3 pretty separate systems whereas the 225 has two sytems but 3 pumps. I suppose I could be difficult by pointing out that the chances of a double hydraulic system failure have got to be miniscule, probably only fire or serious structural damage in which case the 3rd system is going to cop it as well.
Yup, the 225 (also the L2) has the third generator powered by a turbine on the LH hydraulic system. To be fair its an optional extra but all Oil Support operators have it as far as I am aware. Its not massively powerful but does allow unlimited flight time following double TRU or alternator failure with some load shedding. Of course you could also go for the APU, which is another optional extra (std on the 92, but then the 92 doesn't really have a proper battery!)
Autopilot: no, in the 225 the single point failure of AP hydraulics is now removed - the control runs down stream of the AP hydraulics now include series electromechanical actuators (SEMA) that normally do 50% of the AP work (other 50% in AP hydraulic unit) so without the AP hydraulics, you still get all the upper modes working with reduced authority (eg fully coupled ILS down to 80' etc). When you actually try to fly the thing manually with no AP hyd, the controls are stiff as before but you get SAS from the SEMAs so its much easier.
Regarding the cracking, only time will tell. What concerns me about the S92 is the way the considerable vibration inherent in the rotor system is dealt with (try switching of the anti-vibe system to see what I mean)
The anti-vibe system reduces vibration in a local area around it by generating vibration of its own, but 180deg out of phase. This creates two issues,
1) the energy of the inherent vibration is not absorbed by the anti-vibe device, its effect is merely nulled by an equal amount of energy of opposite phase. These colliding energies go somewhere and its absorbed by the structure, via stress to eventually become heat. The heat is no problem but the stress could be.
2) Even if my analysis above is incorrect (but I don't think it is) these anti-vibe devices are only in the cabin/cockpit area, and with their short-range effect they do nothing to reduce the vibration in the rest of the aircraft. This is why operators are seeing cracking in places such as the tailboom area (admitedly non-structural so far)
So whilst you are sitting happily in the (relatively) smooth cockpit/cabin, is the rest of the aircraft shaking itself to bits?
ANR headsets: They sound like a good idea (excuse pun) but the problem is that although they seem to be better, in fact the active part is only able to cancel low frequencies. High frequencies (because of their short wavelength) must be removed my conventional passive sound absorbtion. Because removing the low frequencies makes the sound levels seem much lower, manufacturers pehaps need to bother less about passive sound absorbtion, with the result that high frequency noise levels (and aren't they the problem for pilot's hearing?) may be higher.
It is for this reason alone that I still use a conventional headset. (comes in handy when reading Nick's posts too - then I can't hear the shouting!)
HC
OK, not sure how the 92 hydraulic system hangs together, sounds like there are 3 pretty separate systems whereas the 225 has two sytems but 3 pumps. I suppose I could be difficult by pointing out that the chances of a double hydraulic system failure have got to be miniscule, probably only fire or serious structural damage in which case the 3rd system is going to cop it as well.
Yup, the 225 (also the L2) has the third generator powered by a turbine on the LH hydraulic system. To be fair its an optional extra but all Oil Support operators have it as far as I am aware. Its not massively powerful but does allow unlimited flight time following double TRU or alternator failure with some load shedding. Of course you could also go for the APU, which is another optional extra (std on the 92, but then the 92 doesn't really have a proper battery!)
Autopilot: no, in the 225 the single point failure of AP hydraulics is now removed - the control runs down stream of the AP hydraulics now include series electromechanical actuators (SEMA) that normally do 50% of the AP work (other 50% in AP hydraulic unit) so without the AP hydraulics, you still get all the upper modes working with reduced authority (eg fully coupled ILS down to 80' etc). When you actually try to fly the thing manually with no AP hyd, the controls are stiff as before but you get SAS from the SEMAs so its much easier.
Regarding the cracking, only time will tell. What concerns me about the S92 is the way the considerable vibration inherent in the rotor system is dealt with (try switching of the anti-vibe system to see what I mean)
The anti-vibe system reduces vibration in a local area around it by generating vibration of its own, but 180deg out of phase. This creates two issues,
1) the energy of the inherent vibration is not absorbed by the anti-vibe device, its effect is merely nulled by an equal amount of energy of opposite phase. These colliding energies go somewhere and its absorbed by the structure, via stress to eventually become heat. The heat is no problem but the stress could be.
2) Even if my analysis above is incorrect (but I don't think it is) these anti-vibe devices are only in the cabin/cockpit area, and with their short-range effect they do nothing to reduce the vibration in the rest of the aircraft. This is why operators are seeing cracking in places such as the tailboom area (admitedly non-structural so far)
So whilst you are sitting happily in the (relatively) smooth cockpit/cabin, is the rest of the aircraft shaking itself to bits?
ANR headsets: They sound like a good idea (excuse pun) but the problem is that although they seem to be better, in fact the active part is only able to cancel low frequencies. High frequencies (because of their short wavelength) must be removed my conventional passive sound absorbtion. Because removing the low frequencies makes the sound levels seem much lower, manufacturers pehaps need to bother less about passive sound absorbtion, with the result that high frequency noise levels (and aren't they the problem for pilot's hearing?) may be higher.
It is for this reason alone that I still use a conventional headset. (comes in handy when reading Nick's posts too - then I can't hear the shouting!)
HC
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Shouldn't the title of this thread be S92 vs 225 ?
May I say...very very informative as they are both aircraft I may find myself in, sometime in the not so distant future.
To answer the question How important is crashworthiness VERY!!
May I say...very very informative as they are both aircraft I may find myself in, sometime in the not so distant future.
To answer the question How important is crashworthiness VERY!!