Sikorsky S-92: From Design to Operations
squib66
It is. It’s a shame your post does not note that some operators chose to remove the BCAR approved glass laminated windshield installed by the manufacture of the platform and author of the RFM and install a lightweight cast acrylic screen which in order to obtain similar impact tolerances, could only be achieved at speeds below 109 knots.
FH1100 Pilot
Sikorsky did not certify the S-92 transmission to JAA 29.297(c)(1), that’s the job of the FAA/JAA, so go have the jury ask them.
Now I’m not privy to the FDR/CVR evidence and I’m sure all will be revealed pretty soon, but even in basic training, signs of a loss of oil would be a corresponding increase in oil temperature, would it not?
In PHI / Shell S-76C++ case Sikorsky were quick to point out that the standard windscreen was certified to the higher BCAR requirements.
FH1100 Pilot
Regardless of the particulars of the Cougar crash, Sikorsky is going to have a hard time justifying to a jury how their transmission actually meets the requirements of 29.297(c)(1). Some (like me) would say that it does not. But who knows? The court (or NTSB, or whomever) may find that Sikorsky's assumptions about the trans were perfectly logical and reasonable. That would shut me up right quick.
But the Cougar pilots didn't have full information. All they had was a zero pressure reading, and the knowledge that other S-92's had suffered some kinds of oil pump failures. As we all know and admit, the zero pressure reading should have been enough for them to decide to put 'er down. But they did not. Being humans and not robots, the two of them came to a decision and made a mistake. We can be sure they knew what the RFM called for. We cannot be sure exactly why they disregarded it.
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Hilife
I'm not sure what your point is on the windscreens. I don't think Squib was being critical of Sikorsky's own S-76 windscreens and there is no suggestion Cougar cause their accident by changing the S-92 gearbox!
Sikorsky is the Type Certificate Holder. They applied for the certification and it is their duty to meet the requirements and justify why and how they do.
However as Sikorsky are a US company and the FAA certified the aircraft before the JAA or Transport Canada perhaps the FAA should come clean on their decision making on 927. Did they bow to pressure from Sikorsky?
MOST CRTICAL
If the oil flows out of the gear box the oil temperature sensor will not see any oil and while the gears get very hot - the indicated oil temperature will not rise. You have just made the sort of mistake that perhaps convinced the Cougar crew to delay ditching. The CVR transcript will indeed be interesting.
I'm not sure what your point is on the windscreens. I don't think Squib was being critical of Sikorsky's own S-76 windscreens and there is no suggestion Cougar cause their accident by changing the S-92 gearbox!
Sikorsky is the Type Certificate Holder. They applied for the certification and it is their duty to meet the requirements and justify why and how they do.
However as Sikorsky are a US company and the FAA certified the aircraft before the JAA or Transport Canada perhaps the FAA should come clean on their decision making on 927. Did they bow to pressure from Sikorsky?
MOST CRTICAL
If the oil flows out of the gear box the oil temperature sensor will not see any oil and while the gears get very hot - the indicated oil temperature will not rise. You have just made the sort of mistake that perhaps convinced the Cougar crew to delay ditching. The CVR transcript will indeed be interesting.
while the gears get very hot - the indicated oil temperature will not rise
Variable Load asks a very pertinent question:
Answer: I don't know. I'm a pilot, not an engineer.
But heck, there has to be some way. As far as I know, all helicopter transmissions are "wet-sump" designs. That is, all of the oil is contained in the unit itself, with no external tank. I wonder if it is totally impossible to design a transmission with some sort of external sump? Alternatively, naively, I would think that there has to be some way of measuring the oil quantity in the trans and displaying that info to the pilots. I'd be very surprised if it simply was impossible.
FH1100, how do you have a reliable oil quantity gauge when almost all of the oil is in "circulation" when the gearbox is running?
But heck, there has to be some way. As far as I know, all helicopter transmissions are "wet-sump" designs. That is, all of the oil is contained in the unit itself, with no external tank. I wonder if it is totally impossible to design a transmission with some sort of external sump? Alternatively, naively, I would think that there has to be some way of measuring the oil quantity in the trans and displaying that info to the pilots. I'd be very surprised if it simply was impossible.
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Why not use the oil cooler with a capacitive sensor array, then calculate total trans volume by difference in level change in oil cooler. This would IMO provide a very sensitive oil quantity leak detection system. Only downside would be when cooler bypass is activated, so I would also use localized thermocouple/RTD elements at strategic drive component to measure potential "hot-spots".
We use these condition-based monitoring techniques with main power generation/reciprocating machinery in the oil and gas industry to provide continuous monitoring and alarm indications as well as safety shutdown systems on high-value equipment.
Max
We use these condition-based monitoring techniques with main power generation/reciprocating machinery in the oil and gas industry to provide continuous monitoring and alarm indications as well as safety shutdown systems on high-value equipment.
Max
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FH1100.
I think you need to get off your high horse and stop having a go at everyone and everything on this thread cos you dont like SAC or whatever your gripe is. this is a discussion board not an Argument board.
i was correcting your misleading statement about the sponsons. you suggested the whole lot ripped off because it crashed. well i was pointing out that part of it is meant to rip off. if the crash forces were enough to rip the u/c hardpoints off then it would have also ripped the floats off had they been deployed
i was pointing out the errors of your post based on the DESIGN of the aircraft, which as an engineer qualified on the aircraft type, feel am more informed than you to talk about. this includes what i said about birdstrike tolerance, the example i gave was mearly one of those features. im not trying to defend anything or anyone, or speculate on how succesful the design is or was on that occasion.
The arguments you seem to want to make are not for this thread, try the crash thread, but even there, try to at least discuss, not berate the other posters for having a different opinion.
One more thing. If the FAA passed the aircraft for certification, then i would expect its for them to defend why, not sikorsky.
(combative reply awaited.) (would a "sorry, lets discuss this like adults" be out of the question?)
I think you need to get off your high horse and stop having a go at everyone and everything on this thread cos you dont like SAC or whatever your gripe is. this is a discussion board not an Argument board.
i was correcting your misleading statement about the sponsons. you suggested the whole lot ripped off because it crashed. well i was pointing out that part of it is meant to rip off. if the crash forces were enough to rip the u/c hardpoints off then it would have also ripped the floats off had they been deployed
i was pointing out the errors of your post based on the DESIGN of the aircraft, which as an engineer qualified on the aircraft type, feel am more informed than you to talk about. this includes what i said about birdstrike tolerance, the example i gave was mearly one of those features. im not trying to defend anything or anyone, or speculate on how succesful the design is or was on that occasion.
The arguments you seem to want to make are not for this thread, try the crash thread, but even there, try to at least discuss, not berate the other posters for having a different opinion.
One more thing. If the FAA passed the aircraft for certification, then i would expect its for them to defend why, not sikorsky.
(combative reply awaited.) (would a "sorry, lets discuss this like adults" be out of the question?)
ironchefflay (is that really you, Bobby?), I understand why you take these things so personally. But losing objectivity is never a good thing. I am puzzled though, why you seem to think that once a design is approved by the FAA, the manufacturer/designer has no more responsibility for it.
Curious.
Curious.
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"Finally, it seems astonishing to me that SAC has not yet retrofitted a transmission oil quantity gauge to the S-92. How hard could it be? That's all it would take to eliminate another accident of this type."
FH1100 Pilot,
The oil volume turnover rate in an MRGB like the S-92's is probably about 20 seconds at most. This means the total volume of oil in the lube system circulates from pump-to-sump at least 3 times per minute. If there is a large leak path in the main, single-path circuit (like a dislodged filter housing), then virtually the entire oil supply could easily empty out in less than a minute's time. For such a failure mode, an oil level sensor would not be of much additional benefit.
However, if the leakage was due to something like a shaft seal, and the leakage rate was much less, then an oil level sensor would be of benefit.
If you look at any current aircraft gearbox design (MRGB, AMAD, EMAD, etc.), one thing you'll notice is the absence of external oil lines. The elimination of any potential point of leakage in the lube circuit is something designers strive for. The oil pipes are integrated into the housing casting wherever possible, which makes the casting very expensive, but also greatly improves reliability.
riff_raff
FH1100 Pilot,
The oil volume turnover rate in an MRGB like the S-92's is probably about 20 seconds at most. This means the total volume of oil in the lube system circulates from pump-to-sump at least 3 times per minute. If there is a large leak path in the main, single-path circuit (like a dislodged filter housing), then virtually the entire oil supply could easily empty out in less than a minute's time. For such a failure mode, an oil level sensor would not be of much additional benefit.
However, if the leakage was due to something like a shaft seal, and the leakage rate was much less, then an oil level sensor would be of benefit.
If you look at any current aircraft gearbox design (MRGB, AMAD, EMAD, etc.), one thing you'll notice is the absence of external oil lines. The elimination of any potential point of leakage in the lube circuit is something designers strive for. The oil pipes are integrated into the housing casting wherever possible, which makes the casting very expensive, but also greatly improves reliability.
riff_raff
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I wander, what would a oil quantity gauge change? Wouldn't more data only add to the confusion ? If the oil pressure drops, there is something wrong going on, and you should land ASAP, I don't think it really matter if the problem is leakage, faulty pump, or gauge, all of them pose a serious risk for the flight anyway.
There could be torque gauges added to the shafts to monitor friction between gears, and this could also show a lubrication system malfunction. But still... is there a need for deliberate complication of this system ?
On the other hand it actually amaze me, that in one hand we have a digital system that monitor everything, and in the other we have a strict algorithms to judge what to do in specific situations... and yet the pilot is the one who have to use them. Why can't the system, just tell what is going on ?
If the flight manual say: A:fail + B:ok + C:fail = land ASAP. Why can't the system do this on its own, and just put a sign on the MFD: "Oil system failure. Put me down NOW!" ?
There could be torque gauges added to the shafts to monitor friction between gears, and this could also show a lubrication system malfunction. But still... is there a need for deliberate complication of this system ?
On the other hand it actually amaze me, that in one hand we have a digital system that monitor everything, and in the other we have a strict algorithms to judge what to do in specific situations... and yet the pilot is the one who have to use them. Why can't the system, just tell what is going on ?
If the flight manual say: A:fail + B:ok + C:fail = land ASAP. Why can't the system do this on its own, and just put a sign on the MFD: "Oil system failure. Put me down NOW!" ?
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FH1100, I will take you up on a couple of your points in order to balance the "discussion" a little. I would argue that the S92 is probably inherently one of the safest helicopters in operation today. In six years of service and over 250,000 flight hours, there has been one accident, which arguably should have not been fatal. Certainly the training I received when I did a type rating on the S92 (2 years before this accident) was perfectly clear about the course of action in event of total loss of pressure in the MGB. Since 2004 the Puma fleet has suffered 16 accidents, including a disintegration of the MGB, which everyone seem conveniently to have forgotten. Whilst I appreciate there are more Puma variants in use around the world, and hours flown are greater, according to EC the Puma and its derivatives have recently clocked up 4 million hours total, since 1992. So call that an average of 220,000 per year. 880K over the 4 year period and 16 accidents. Statistically that is one every 55,000hrs compared to one every 250,000 on the 92. Now I am not one for statistics, but as your comments indicate you want to see something demonstrated this is a start. (numbers from EC and SAC)
Statistics only give us a historical picture and of course I am not claiming it is the full picture, and you must allow for various factors, but all the evidence provided in all studies, including those done by our oil company customers does suggest that a more modern aircraft has provided a significant improvement in safety.
Avionics It is true that avionics can be retrofitted to most, but not all aircraft. It is not always practical and is not always straightforward, nor always cost-efficient. The Rockwell Collins AMS has proven to be extremely robust and reliable. The high level of redundancy and cross-comparison does provide a very real improvement over older types. There are arguably better systems available now, but in my career, having flown some 9 other types this is the most reliable and best I have used. It is also very stable in the event of electrical surges such as from lightning strikes and static discharges. There have been some failures of course and there have been issues with the DCU's in instances, but so far a total electrical failure has yet to happen, and even in the all of the lightning strikes that I am aware of, including one of my own, no electrical/avionic systems have failed. The same cannot be said of the EC's flying around. Hopefully an engineer can pipe in here an explain a little more than I. So yes it is a big deal
Floats It has Sea State 6 floats. They are not just in the sponsons, but also in the nose and under the tail. If a crash is heavy enough to pull the sponsons off then it is unlikely there will be much left of any other part of the machine either, so an irrelevant point. Where it would help though is that if you do ditch in rough cold seas you have a good chance of staying upright long enough to get out of the emergency exits. Of emergency exits - there are as you pointed out more of them and they are bigger. Very comforting if you are that Pax trying to get out, and someone in front of you is injured, or blocking the exit. So worth a lot I would say. Or if the aircraft does tip, at least you closest exit is very close, and you dont have to go swimming to find the next one.
Bird-strike protection As was mentioned by someone with experience in this field and you promptly snubbed, there is a lot more to protection than simply changing the windscreen. The throttle levers are also better protected, especially compared to the L1/L2, to prevent anything coming through the windscreen and chopping the engines for you, as was possibly the cause in the PHI S76 accident.
What do you think happened to the 139 in Hong Kong harbour this year. That bird somehow missed the hulking mass, and granted it hit the rotor not the pylon, it could just as easily hit that, especially if the helicopter is climbing, such as on departure, and the bird is upwind, in front of you. So no it doesn't have to be the bird that hits the helicopter from above. This has happened numerous times in the past, and bird strikes to the tail have taken down aircraft.
RIPS- Rotor Ice Protection System -
Have you actually flown offshore? Yes icing is a problem, and continues to be one. The effect on performance can be very dramatic, and very quick. It is believed to possibly have been the cause of a chinook crash in Afghanistan in 2007, with the loss of 8 soldiers. Combine blade icing and an engine failure and you have big problems. There is a performance penalty with RIPS, but you will at least have clear blades when you need them most. The system is also now reliable and works well. We usually operate to ensure a positive, clear area area of at least 500' below, to ensure an escape if RIPS fails. Having flown in heavy icing, it is a big improvement. It allows us to fly safely, when otherwise we could not. Dispatching into "known icing" is absolutely not a problem, if done and planned for properly and I don't know why you think it is. We have been doing it for years in other types, with limited clearance, monitoring the build up, and descending or vacating once the build up was too much. We would not operate in winter if we couldn't. The RIPS gives us a much greater freedom of movement in the sky, and is inherently safer, due to the fact it is clearing our blades of ice constantly.
A oil quantity gauge - as has already been mentioned, is firstly not much use, as the pressure is the most important thing. It really does not matter that much how much oil is in there - if you have zero pressure, you need to get down - NOW. Everything else is irrelevant.
I hope this adds another perspective, and is not intended as a sales pitch, but is from my "coal-face" perspective, with a reasonably good insight to the aircraft having flown several thousand hours on it and being able to compare it to several other types directly. It is all good and well to rant and bitch, but the reality is that emotion has injected a disproportionate and in many cases ill informed and inaccurate amount of bad press toward the aircraft, which has certainly caused some to have a very skewed perspective.
Okay, it seems to me that the S-92 does not bring all that much that's really new to the industry that makes it demonstrably or measurably "safer" than anything else out there.
Sadly, as we've seen in reality, the S-92 is not proving to be all that much safer than anything else. Maybe less safe compared to helicopters that actually *do* have emergency lubrication systems (not that cockamamie emergency bypass system). But hey, it is fancy and new!
Avionics It is true that avionics can be retrofitted to most, but not all aircraft. It is not always practical and is not always straightforward, nor always cost-efficient. The Rockwell Collins AMS has proven to be extremely robust and reliable. The high level of redundancy and cross-comparison does provide a very real improvement over older types. There are arguably better systems available now, but in my career, having flown some 9 other types this is the most reliable and best I have used. It is also very stable in the event of electrical surges such as from lightning strikes and static discharges. There have been some failures of course and there have been issues with the DCU's in instances, but so far a total electrical failure has yet to happen, and even in the all of the lightning strikes that I am aware of, including one of my own, no electrical/avionic systems have failed. The same cannot be said of the EC's flying around. Hopefully an engineer can pipe in here an explain a little more than I. So yes it is a big deal
Floats It has Sea State 6 floats. They are not just in the sponsons, but also in the nose and under the tail. If a crash is heavy enough to pull the sponsons off then it is unlikely there will be much left of any other part of the machine either, so an irrelevant point. Where it would help though is that if you do ditch in rough cold seas you have a good chance of staying upright long enough to get out of the emergency exits. Of emergency exits - there are as you pointed out more of them and they are bigger. Very comforting if you are that Pax trying to get out, and someone in front of you is injured, or blocking the exit. So worth a lot I would say. Or if the aircraft does tip, at least you closest exit is very close, and you dont have to go swimming to find the next one.
Bird-strike protection As was mentioned by someone with experience in this field and you promptly snubbed, there is a lot more to protection than simply changing the windscreen. The throttle levers are also better protected, especially compared to the L1/L2, to prevent anything coming through the windscreen and chopping the engines for you, as was possibly the cause in the PHI S76 accident.
Oh, please. So...we're thinking that a bird could strike the tail rotor pylon then? I'm curious as to how a bird could bypass the huge, hulking mass of fuselage and rotor system to find its way to a direct hit on the inclined tail rotor driveshaft. From above, perhaps? And again I ask: How many t/r pylon birdstrikes have been recorded over the years? Seems to me that SAC is touting as yet another "SAFETY FEATURE!!!" something that is arguably so. I mean, let's be honest here; just because they say it, does that make it true?
RIPS- Rotor Ice Protection System -
But...let me ask, has icing been a problem in the past? Have we lost any aircraft in the North Sea or North Atlantic due to MRB icing? Secondly, I'm not sure I'm in love with the idea of dispatching into "known ice" IN A HELICOPTER. I guess we'd have to get "Shell Management" to weigh-in on whether his company would approve launching when "known ice" exists. So while RIPS *is* a real technical advancement, I'm not so sure that it makes the helicopter absolutely "safer." I think that's arguable. (Okay, I know icing can occur even when it's not forecast. Has this been a problem in the past?)
A oil quantity gauge - as has already been mentioned, is firstly not much use, as the pressure is the most important thing. It really does not matter that much how much oil is in there - if you have zero pressure, you need to get down - NOW. Everything else is irrelevant.
I hope this adds another perspective, and is not intended as a sales pitch, but is from my "coal-face" perspective, with a reasonably good insight to the aircraft having flown several thousand hours on it and being able to compare it to several other types directly. It is all good and well to rant and bitch, but the reality is that emotion has injected a disproportionate and in many cases ill informed and inaccurate amount of bad press toward the aircraft, which has certainly caused some to have a very skewed perspective.
Horror Box, thanks for the reasoned counterpoint. I appreciate your perspective on the machine. One *minor* disagreement though...
I did not snub it. All I was saying was that in my lifetime in this industry, I've never heard of *ONE* instance of a bird impacting the tail rotor pylon and taking out the t/r driveshaft. So claiming that moving the driveshaft to the rear of the pylon is a "safety" feature is...well...arguable I think.
In fact, I am all for improved bird-strike protection on the front of the aircraft. It's not just about the windscreens and what they're made of, obviously. It's also about the structural integrity of the centrepost, upper cockpit, and those cowlings "in the line of fire" so to speak. I thought I had made that clear. Hey, I fly a 206 with flimsy plastic windscreens and big, long, vulnerable push-pull tubes going up to the rotor. My worst nightmare is having a big bird either come through the screen on my side at night or (worse), taking out one of my push-pull tubes.
As for avionics, I was surprised to be flipping through one of the helicopter-specific magazines recently and seeing...I forget whether it was a CH-47 or an old S-61 with nothing but glass panels up front. Either way it was a 1st-Gen airframe with what looked like the latest-and-greatest cockpit displays.
I don't hate the S-92. As I've said all along, I'm sure the S-92 is a wonderful aircraft with many new features. Whether these features give us a helicopter that is substantially or demonstrably "safer" than anything else on the market is, as I've said, arguable. It's foolish to assume that the oil companies have the last word on what is or is not safe. But you're right, so far its accident record has been pretty good, comparatively.
Again, thank you for your thoughtful post.
As was mentioned by someone with experience in this field and you promptly snubbed...
In fact, I am all for improved bird-strike protection on the front of the aircraft. It's not just about the windscreens and what they're made of, obviously. It's also about the structural integrity of the centrepost, upper cockpit, and those cowlings "in the line of fire" so to speak. I thought I had made that clear. Hey, I fly a 206 with flimsy plastic windscreens and big, long, vulnerable push-pull tubes going up to the rotor. My worst nightmare is having a big bird either come through the screen on my side at night or (worse), taking out one of my push-pull tubes.
As for avionics, I was surprised to be flipping through one of the helicopter-specific magazines recently and seeing...I forget whether it was a CH-47 or an old S-61 with nothing but glass panels up front. Either way it was a 1st-Gen airframe with what looked like the latest-and-greatest cockpit displays.
I don't hate the S-92. As I've said all along, I'm sure the S-92 is a wonderful aircraft with many new features. Whether these features give us a helicopter that is substantially or demonstrably "safer" than anything else on the market is, as I've said, arguable. It's foolish to assume that the oil companies have the last word on what is or is not safe. But you're right, so far its accident record has been pretty good, comparatively.
Again, thank you for your thoughtful post.
HB - it is only conjecture that the 139 in HK was hit by a bird unless you have info from the investigation.
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Crab - you are quite right, as far as I am aware nothing has been confirmed, but it is still a plausible explanation.
FH1100,
Personally I think the rationale is sound, but of course everything is arguable, and this thread would be rather boring and pointless if we all agreed on everything all the time!
FH1100,
So claiming that moving the driveshaft to the rear of the pylon is a "safety" feature is...well...arguable I think.
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Horror box
I agree with you with regard to the TRDS postioning being a positive. The fact remains the testing for the S-92 was with a smaller bird than the BCAR AS332L2 testing.
The newer S-92 floats were said to have a 'limited SS6' capacity in the Canadian public inquiry. The original floats, as used at the time by Cougar, were SS5 with just 3 bags.
I for one can still remember where I was when I heard about the April 2009 AS332L2 accident. The difference in that case is that there are no indications that this was caused by an known inadequate feature that had made it through certification on a technicality.
I commend you for aiming to use real performance data. In your accident analysis you have missed the first (non-fatal) S-92 accident (the Korean aircraft). For clarification I have 3 questions:
1. Can you confirm if all the AS332 family accidents were hull losses?
2. Can you also confirm how many the AS332 family accidents were fatal accidents?
3. Can you also confirm how many the AS332 family accidents were civil accidents?
4. What proportion of the AS332 family accidents were 'operational' rather than 'airworthiness' accidents?
I agree with you with regard to the TRDS postioning being a positive. The fact remains the testing for the S-92 was with a smaller bird than the BCAR AS332L2 testing.
The newer S-92 floats were said to have a 'limited SS6' capacity in the Canadian public inquiry. The original floats, as used at the time by Cougar, were SS5 with just 3 bags.
I for one can still remember where I was when I heard about the April 2009 AS332L2 accident. The difference in that case is that there are no indications that this was caused by an known inadequate feature that had made it through certification on a technicality.
I commend you for aiming to use real performance data. In your accident analysis you have missed the first (non-fatal) S-92 accident (the Korean aircraft). For clarification I have 3 questions:
1. Can you confirm if all the AS332 family accidents were hull losses?
2. Can you also confirm how many the AS332 family accidents were fatal accidents?
3. Can you also confirm how many the AS332 family accidents were civil accidents?
4. What proportion of the AS332 family accidents were 'operational' rather than 'airworthiness' accidents?
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Wasnt the Korean crash CFIT in bad weather?
as for the 332L2 accident last year, i could be argued that there was a design issue with the gearboxes that prevented discovery of the problem.
i wont go into detail as im not sure what detail is in the public domain, so im not going to get in to it. also because i knew somone who was onboard the flight.
there does seem to be an element of selective disgruntledness going on here. there have been a number of incidents involving the S92 but equally there have been problems with with the Puma, weather it be the L, L2 or 225 and every other aircraft in the indusrty! we fly all heavy and medium types in popular use for offshore crewchange and police/EMS and every aircraft has its problems. my personal experience with the aircraft as an engineer, is that it is much more reliable that the Puma including the 225. but thats just a personal opinion, not backed up by any facts or figures.
one point i would make before making any comment. read the report that has been published so far and in particular, the configuration and actions of the aircraft before ditching. i am making no claims about anything. i just think you should make sure you are aware of the facts that have been revealed so far.
as for the 332L2 accident last year, i could be argued that there was a design issue with the gearboxes that prevented discovery of the problem.
i wont go into detail as im not sure what detail is in the public domain, so im not going to get in to it. also because i knew somone who was onboard the flight.
there does seem to be an element of selective disgruntledness going on here. there have been a number of incidents involving the S92 but equally there have been problems with with the Puma, weather it be the L, L2 or 225 and every other aircraft in the indusrty! we fly all heavy and medium types in popular use for offshore crewchange and police/EMS and every aircraft has its problems. my personal experience with the aircraft as an engineer, is that it is much more reliable that the Puma including the 225. but thats just a personal opinion, not backed up by any facts or figures.
one point i would make before making any comment. read the report that has been published so far and in particular, the configuration and actions of the aircraft before ditching. i am making no claims about anything. i just think you should make sure you are aware of the facts that have been revealed so far.
Last edited by ironchefflay; 3rd Nov 2010 at 23:09.
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Yes, the Korean accident was a CFIT in bad weather. Luckily everyone got out before it was destroyed by fire.
I see Horror Box has not supplied further data on the AS332 accidents. While I am a strong believer in the benefits of the latest certification standards I don't recall the 332 familiy rate being as bad as he portrays.
On the matter of certifying to the latest standards, there had been questions within Shell Aircraft's experts over the ‘robustness’ of S92 MRGB certification process. Iin particular that the loss of oil event through filter housing was “extremely unlikely”, implying this this single barrier would be subject to no human error! This was at a time that other S92 MRGB design issues, highlighted by 2 BSP S92 incidents, remained only partially resolved.
This meant that as part of the SAI safety case, contracting limitations were imposed on the S92 type until the way ahead on MGB issues was resolved, with the S92 being decalred a “ non-preferred heavy helo option” with option of operational limitations remaining a possibility.
The good news
is that Shell Aircraft's continued engagement with Sikorsky on MRGB improvements has resulted in a return to a safe status quo and their is no justification for all this infantile scaremongering.
I see Horror Box has not supplied further data on the AS332 accidents. While I am a strong believer in the benefits of the latest certification standards I don't recall the 332 familiy rate being as bad as he portrays.
On the matter of certifying to the latest standards, there had been questions within Shell Aircraft's experts over the ‘robustness’ of S92 MRGB certification process. Iin particular that the loss of oil event through filter housing was “extremely unlikely”, implying this this single barrier would be subject to no human error! This was at a time that other S92 MRGB design issues, highlighted by 2 BSP S92 incidents, remained only partially resolved.
This meant that as part of the SAI safety case, contracting limitations were imposed on the S92 type until the way ahead on MGB issues was resolved, with the S92 being decalred a “ non-preferred heavy helo option” with option of operational limitations remaining a possibility.
The good news
is that Shell Aircraft's continued engagement with Sikorsky on MRGB improvements has resulted in a return to a safe status quo and their is no justification for all this infantile scaremongering.
"Shell Management" 
states:
Extremely unlikely? What's the definition of that term? Is that an arbitrary term Shell made up? In Chapter 3 of the FAA's System Safety Handbook, they use and define the terms: Probable, Remote, Extremely Remote, Extremely Improbable. Nowhere do we see the term "extremely unlikely" used.
"Shell Management" goes on:
Infantile. Yes, voicing safety concerns over innocent, paying passengers is "infantile."
I guess what you're saying, "Shell Management" is that with the switch in material of the mounting studs, Sikorsky completely eliminated the oil filter housing as a possible source of a leak. Have I got that right?
Because no matter what you make those studs out of - unobtainium for all I care - that mounting pad and seal are still a place where a catastrophic leak can occur. To deny this is...well, to use your own term, infantile. (Not to mention all of the other potential leak sources on that transmission.) The S-92 is surely a very safe helicopter in most respects. Except...except for that dang transmission, which has proven to be no safer than any other transmission in service. And that transmission is the most important thing on the helicopter when you take people a long way out over a cold, inhospitable ocean. In fact, because of its inability to last more than 10 minutes after a genuine loss of oil, it might be argued that the S-92 is less safe than a 332 or Merlin.
All you guys who wish to put blinders on and downplay this issue because of the otherwise overwhelming greatness of the S-92, fine by me. But you know what? I think we owe our passengers a higher duty of care than that.
Your mileage may vary.
states:
On the matter of certifying to the latest standards, there had been questions within Shell Aircraft's experts over the ‘robustness’ of S92 MRGB certification process. Iin particular that the loss of oil event through filter housing was “extremely unlikely”, implying this this single barrier would be subject to no human error! This was at a time that other S92 MRGB design issues, highlighted by 2 BSP S92 incidents, remained only partially resolved. 
"Shell Management" goes on:
The good news 
is that Shell Aircraft's continued engagement with Sikorsky on MRGB improvements has resulted in a return to a safe status
quo and their is no justification for all this infantile scaremongering.
is that Shell Aircraft's continued engagement with Sikorsky on MRGB improvements has resulted in a return to a safe status quo and their is no justification for all this infantile scaremongering.
I guess what you're saying, "Shell Management" is that with the switch in material of the mounting studs, Sikorsky completely eliminated the oil filter housing as a possible source of a leak. Have I got that right?
Because no matter what you make those studs out of - unobtainium for all I care - that mounting pad and seal are still a place where a catastrophic leak can occur. To deny this is...well, to use your own term, infantile. (Not to mention all of the other potential leak sources on that transmission.) The S-92 is surely a very safe helicopter in most respects. Except...except for that dang transmission, which has proven to be no safer than any other transmission in service. And that transmission is the most important thing on the helicopter when you take people a long way out over a cold, inhospitable ocean. In fact, because of its inability to last more than 10 minutes after a genuine loss of oil, it might be argued that the S-92 is less safe than a 332 or Merlin.
All you guys who wish to put blinders on and downplay this issue because of the otherwise overwhelming greatness of the S-92, fine by me. But you know what? I think we owe our passengers a higher duty of care than that.
Your mileage may vary.
What type of filter mounting system do the other types you have mentioned have FH1100?
Have you seen the latest S-92 filter mount? Have you seen the 6 bolt mount on the new casting?
Do you think it is better or worse than the other aircraft types?
Have you seen the latest S-92 filter mount? Have you seen the 6 bolt mount on the new casting?
Do you think it is better or worse than the other aircraft types?