Hard Core Category A?
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Hard Core Category A?
The concept of complete protection from engine failure was discussed in a previous thread, lets kick it off here.
One side says that the engine is prone enough to failure that it is wise to design a helicopter that has complete coverage of its flight path so that engine failure can occur without probability of a mishap. Let's call this hover to hover or "full Cat A".
The other side says that a limited exposure where an engine failure can result in a hard landing is acceptable, as long as it can be shown that the probability of an engine failure in that exposure time is as slight as the other kinds of failures that can happen to a helicopter. Lets call that "limited exposure."
It is my belief that the ability of a helicopter to land on a small heliport or rig helideck with full Cat A will reduce payload substantially, so that the economics of the operation would be strongly impacted, and also that such full Cat A would not increase the actual safety of the operation, as long as limited exposure rules were applied.
It has been compared to jet airplanes, where full Cat A equivilents are had regularly. I contend that they are actually a special case, because the turbojets that are used to cruise at 30,000 feet have enormous thermodynamic power potential at low altitudes, so the Cat A is actually free to the design. Furthermore, if we asked that plane to take off full Cat A from a small airfield, we would then hear similar squawks from the designers.
I also contend that actual accident data for helicopters that have good enroute Cat A capabilities, but not full Cat A are subject to many more prevalent causes of accident, and we should spend the next dollar fixing those first. The money and economic damage wrought by full Cat A would actually reduce the safety of the operation, since the money that might have bought EGPWS and weather radar and TCAS and GPS precision approaches would be diverted to the engines instead.
Let the games begin!
One side says that the engine is prone enough to failure that it is wise to design a helicopter that has complete coverage of its flight path so that engine failure can occur without probability of a mishap. Let's call this hover to hover or "full Cat A".
The other side says that a limited exposure where an engine failure can result in a hard landing is acceptable, as long as it can be shown that the probability of an engine failure in that exposure time is as slight as the other kinds of failures that can happen to a helicopter. Lets call that "limited exposure."
It is my belief that the ability of a helicopter to land on a small heliport or rig helideck with full Cat A will reduce payload substantially, so that the economics of the operation would be strongly impacted, and also that such full Cat A would not increase the actual safety of the operation, as long as limited exposure rules were applied.
It has been compared to jet airplanes, where full Cat A equivilents are had regularly. I contend that they are actually a special case, because the turbojets that are used to cruise at 30,000 feet have enormous thermodynamic power potential at low altitudes, so the Cat A is actually free to the design. Furthermore, if we asked that plane to take off full Cat A from a small airfield, we would then hear similar squawks from the designers.
I also contend that actual accident data for helicopters that have good enroute Cat A capabilities, but not full Cat A are subject to many more prevalent causes of accident, and we should spend the next dollar fixing those first. The money and economic damage wrought by full Cat A would actually reduce the safety of the operation, since the money that might have bought EGPWS and weather radar and TCAS and GPS precision approaches would be diverted to the engines instead.
Let the games begin!
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I tend to agree with Nick, ...problems occur when contract negiotions try to make a/c fly to their maximum payload possibilities not allowing for enough operational performance margins.....
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Great idea for discussion!
I'm in violent agreement with the 'limited exposure' concept.
We accept exposure to risk in helicopters in other areas that, on first glance, would take your breath away - this is on the quite reasonable point that it is actually a much lower risk than the other way of doing the job. Putting people onto tall power pylons is a good example - the risk from doing it by helicopter is far less than having the people climb up the pole.
To a certain extent, it's true for using helicopters to go to oil rigs.
We need to examine the engine failure rates and determine if the assumptions are still valid about rate of failure per 100,000 flight hour.
Can we also invoke the fixed wing single engine IFR / night logic? WIth the proper engine (read PT-6 for all intents and purposes) and the correct maintenance procedures, it's not accepted as being safer than twin piston light twins.
If we can show a substantial improvement in cost-effectiveness, then we need to explore it.
And anything to make it simpler to plan and fly such profiles is essential - trying to work out the parameters for Category A on some helicopters is enough to make John Kerry Republican...
I'm in violent agreement with the 'limited exposure' concept.
We accept exposure to risk in helicopters in other areas that, on first glance, would take your breath away - this is on the quite reasonable point that it is actually a much lower risk than the other way of doing the job. Putting people onto tall power pylons is a good example - the risk from doing it by helicopter is far less than having the people climb up the pole.
To a certain extent, it's true for using helicopters to go to oil rigs.
We need to examine the engine failure rates and determine if the assumptions are still valid about rate of failure per 100,000 flight hour.
Can we also invoke the fixed wing single engine IFR / night logic? WIth the proper engine (read PT-6 for all intents and purposes) and the correct maintenance procedures, it's not accepted as being safer than twin piston light twins.
If we can show a substantial improvement in cost-effectiveness, then we need to explore it.
And anything to make it simpler to plan and fly such profiles is essential - trying to work out the parameters for Category A on some helicopters is enough to make John Kerry Republican...
This is an edited extract from that posted on the EC225 thread (JimL):
When the 1995 version of JAR-OPS 3 was written in the early 90s it was decided that it would have to be in compliance with ICAO Annex 6 Part III; this required (even for Operations in Performance Class 2) the provision of deck-edge clearance and (for operations in a hostile environment) flyaway; which in effect - for the North Sea - was a zero exposure regime; existing operations were grandfathered until 2010.
Around the time of the implementation date of 1995, the discussion on offshore performance was centred on how to show compliance with zero exposure. Informed wisdom at that time was that this could only be achieved with Category A helideck procedures (as one of the requirements was to show the 15’ deck edge clearance). However, such procedures that were in existence (very few at that time) could only provide limited approach/take-off directions with a minimum deck size of 2D (shortly after that Sikorsky provided a S76C+ procedure with a minimum deck size of 1.5D).
With this in mind, working groups extensively explored the problem and decide to concentrate on a solution based upon the concept of ‘exposure time’ -
212man has said that it is a shame that we cannot reproduce the performance of the ETOPS twins that are now the backbone of the transatlantic fleet. None of us would disagree with that but it must be understood that we have in our hands the most flexible aviation tool that has ever been produced and the provision of that flexibility comes at a cost. One of the costs of that (expensive provision of) flexibility is the longevity of equipment; whatever (operational) regulations are specified, they apply to the whole population of helicopters - older helicopters could be protected (grandfathered) but this cannot be to the detriment of newer craft which are by definition safer and more expensive but not necessarily more productive (see the previous discussion on the provision of the crashworthy floor for the EC225).
Another trade-off is the installed power to provide: adequate OEI power in the cruise; fuel consumption to ensure adequate payload/range; and power to eliminate/reduce the exposure to an engine failure on take-off or landing. You will already know that provision of these conflicting features (simplistically) is a trade off between the last two - fuel burn and take-off /landing performance (the AB139 argument put forward by Nick).
Discussions in the JAA over the last couple of years have been concerned with what to do in 2010 when the exposure time concept is due to end. Perceived wisdom now has it that there may be a method of providing zero exposure without reverting to Category A procedures. It would appear that, at least for the later versions of the AS332, B412, S76, EC225, S92 and of course the AB139, zero exposure is possible with the provision of risk assessed take-off and landing procedures giving deck-edge clearance and, for those helidecks that are situated in a hostile environment, a limitation on drop down to avoid ditching. It has been observed that such performance is possible even in ISA nil wind conditions.
Using the inherent environmental conditions that obtain in the North Sea which appear to indicate that:
As was indicated in a previous post, the provision of regulations is not the bottom line; some customers have a duty of care that extends well beyond compliance with regulations. It has become increasingly clear that ‘standards’ are within the bailiwick of the customer and not the operator; it is those customers who will specify whether the certification, performance, operational equipment and staff training standards are adequate and, with the exception of certification, will ensure that they are raised if they are not!
When the 1995 version of JAR-OPS 3 was written in the early 90s it was decided that it would have to be in compliance with ICAO Annex 6 Part III; this required (even for Operations in Performance Class 2) the provision of deck-edge clearance and (for operations in a hostile environment) flyaway; which in effect - for the North Sea - was a zero exposure regime; existing operations were grandfathered until 2010.
Around the time of the implementation date of 1995, the discussion on offshore performance was centred on how to show compliance with zero exposure. Informed wisdom at that time was that this could only be achieved with Category A helideck procedures (as one of the requirements was to show the 15’ deck edge clearance). However, such procedures that were in existence (very few at that time) could only provide limited approach/take-off directions with a minimum deck size of 2D (shortly after that Sikorsky provided a S76C+ procedure with a minimum deck size of 1.5D).
With this in mind, working groups extensively explored the problem and decide to concentrate on a solution based upon the concept of ‘exposure time’ -
212man has said that it is a shame that we cannot reproduce the performance of the ETOPS twins that are now the backbone of the transatlantic fleet. None of us would disagree with that but it must be understood that we have in our hands the most flexible aviation tool that has ever been produced and the provision of that flexibility comes at a cost. One of the costs of that (expensive provision of) flexibility is the longevity of equipment; whatever (operational) regulations are specified, they apply to the whole population of helicopters - older helicopters could be protected (grandfathered) but this cannot be to the detriment of newer craft which are by definition safer and more expensive but not necessarily more productive (see the previous discussion on the provision of the crashworthy floor for the EC225).
Another trade-off is the installed power to provide: adequate OEI power in the cruise; fuel consumption to ensure adequate payload/range; and power to eliminate/reduce the exposure to an engine failure on take-off or landing. You will already know that provision of these conflicting features (simplistically) is a trade off between the last two - fuel burn and take-off /landing performance (the AB139 argument put forward by Nick).
Discussions in the JAA over the last couple of years have been concerned with what to do in 2010 when the exposure time concept is due to end. Perceived wisdom now has it that there may be a method of providing zero exposure without reverting to Category A procedures. It would appear that, at least for the later versions of the AS332, B412, S76, EC225, S92 and of course the AB139, zero exposure is possible with the provision of risk assessed take-off and landing procedures giving deck-edge clearance and, for those helidecks that are situated in a hostile environment, a limitation on drop down to avoid ditching. It has been observed that such performance is possible even in ISA nil wind conditions.
Using the inherent environmental conditions that obtain in the North Sea which appear to indicate that:
As was indicated in a previous post, the provision of regulations is not the bottom line; some customers have a duty of care that extends well beyond compliance with regulations. It has become increasingly clear that ‘standards’ are within the bailiwick of the customer and not the operator; it is those customers who will specify whether the certification, performance, operational equipment and staff training standards are adequate and, with the exception of certification, will ensure that they are raised if they are not!
This is not an attempt to turn this into an academic exercise but, as with all philosophical discussions, we need to ensure that we use a common vocabulary so that we can all map to the same mental pictures. Terms that are in common usage have therefore been reproduced - first the definition of Category A:
Nick is using imaginative and descriptive language that has already been encapsulated into definitions - the following are those contained in ICAO (amended to account for recent work):
When discussing take-off and landing procedures, analogies with fixed wing are not, in my view, very helpful as aeroplanes operate to runways where the obstacle environment is controlled; helicopters on the other hand can operate to locations which are analogous to runways covered in, and surrounded by, obstacles.
If you are beginning to infer from this that I am about to put a case against operations in PC2 or operations with exposure that is not correct The aim of this post was only to ensure that we can all group around the same concepts when discussing this extremely important subject.
Nick is using imaginative and descriptive language that has already been encapsulated into definitions - the following are those contained in ICAO (amended to account for recent work):
When discussing take-off and landing procedures, analogies with fixed wing are not, in my view, very helpful as aeroplanes operate to runways where the obstacle environment is controlled; helicopters on the other hand can operate to locations which are analogous to runways covered in, and surrounded by, obstacles.
If you are beginning to infer from this that I am about to put a case against operations in PC2 or operations with exposure that is not correct The aim of this post was only to ensure that we can all group around the same concepts when discussing this extremely important subject.
Suppose it takes 1100 kw to fly 12 pax on 200 Nm at 5000 ft with 25 C OAT. Because of financial issues what has been done so far was to install 2 engines of say 700 kw each and it has been up to the regulatory agencies, operators and crews to design, implement and follow procedures and limitations to deal with this shortage of power on one engine.
Today nobody questions the necessity or redundant hydraulic, fuel and electric systems but we all agree - intellectually too - to operate underpowered helicopters.
IMO in the case above 2 engines of 1100 EACH should be installed so that the helo could hover on ONE engine under the above conditions. This is what a real twin engine is.
On the long term run the financial impact should not be that negative since the engines would be operated almost all the time far from their limits, thus increasing their reliability. Think about the numbers of engines changes worldwide because they work close to the limits.
Above all this safety issue would be settled once and for all.
The major oil companies make tremendous profits and through their aviation advisors they seem to have the final word on selecting the type of helicopter. So I think that they should be gently forced to accept the financial constraints for safer ops.
Cheers
ATN
Today nobody questions the necessity or redundant hydraulic, fuel and electric systems but we all agree - intellectually too - to operate underpowered helicopters.
IMO in the case above 2 engines of 1100 EACH should be installed so that the helo could hover on ONE engine under the above conditions. This is what a real twin engine is.
On the long term run the financial impact should not be that negative since the engines would be operated almost all the time far from their limits, thus increasing their reliability. Think about the numbers of engines changes worldwide because they work close to the limits.
Above all this safety issue would be settled once and for all.
The major oil companies make tremendous profits and through their aviation advisors they seem to have the final word on selecting the type of helicopter. So I think that they should be gently forced to accept the financial constraints for safer ops.
Cheers
ATN
The down side ATN is that the engines run a long way off their design point and so are very thirsty; but hey, that's not my problem! With arriel 2C1s currently being changed at around 1200 hours in the 155 B due to failed power assurance checks, maybe you're point about reliability is valid. 820 C can't be a good T4 to run at all day long.
My concern expressed in the other thread is that having developed the concept of exposure time for the offshore environment, there is a move to allow it for onshore operations too, by both operators and at least one manufacturer (don't mention grandfathers!) and one assumes others too.
We are not talking about Cat A, per se, either; we are talking about Operational regulations as defined in Ops 3 and Annex 6, not the certification standards.
Nick makes a slightly misleading statement in suggesting exposure time is an area within which a hard landing may occur. It is actually an area where a catastrophic crash can occur! Quite legally. This is a fundamental difference; we are not talking about Class 2 criteria, we are proposing allowing large aircraft with members of the fare paying public to operate in a regulatory environment where if the aircraft loses an engine they will quite likely die.
Ignore the offshore oil industry, it's a slightly different case and in any event I genuinly feel that the exposure is very small and insignificant. Look at sheduled helicopter operations; Isles of Scillies S-61, Vancouver S-76, Macau and Hong Kong 76 and others too, no doubt. These have members of the public walking off thee street to travel on a commercial air transport airline. They check in, pass security, have departure lounges and the staff all look like airline staff. The pilots wear white shirts and bars and even ties.
One could forgive them for thinking that the regulations afford them the same protection that they enjoy when flying in a Saab 340 or Beech 1900, for instance (both many times cheaper than an EC-155 or S-76), but no that is not the case.
Instead, the manufacturer says to the regulator "look, it's too hard to do this and costs too much. Why don't we say that for 9 seconds during take off, if an engine fails, we have no idea what will happen to the aircraft and if there are hard immovable objects in the way, well that's just a statistical risk we can take based on creative use of past engine data failure." "oh, and by the way, can we ignore things like governor run downs as they're not really engine failures are they? Oh, and this is a new engine airframe combination, so we don't have a real data set, so guess what; the results are skewed!"
Great! That's progress! Performance is pretty marginal anyway without degrading it further.
I fully accept that the flexibility of this aircraft places it in many varied situations where the crew and other personnel (long lining, power line patrols, SAR etc) are in some risk. However they know that and accept it. What I disagree with is the idea that we can legislate the exposure concept for onshore commercial air transport with fee paying, ignorant (in the literal sense!) members of the public.
My concern expressed in the other thread is that having developed the concept of exposure time for the offshore environment, there is a move to allow it for onshore operations too, by both operators and at least one manufacturer (don't mention grandfathers!) and one assumes others too.
We are not talking about Cat A, per se, either; we are talking about Operational regulations as defined in Ops 3 and Annex 6, not the certification standards.
Nick makes a slightly misleading statement in suggesting exposure time is an area within which a hard landing may occur. It is actually an area where a catastrophic crash can occur! Quite legally. This is a fundamental difference; we are not talking about Class 2 criteria, we are proposing allowing large aircraft with members of the fare paying public to operate in a regulatory environment where if the aircraft loses an engine they will quite likely die.
Ignore the offshore oil industry, it's a slightly different case and in any event I genuinly feel that the exposure is very small and insignificant. Look at sheduled helicopter operations; Isles of Scillies S-61, Vancouver S-76, Macau and Hong Kong 76 and others too, no doubt. These have members of the public walking off thee street to travel on a commercial air transport airline. They check in, pass security, have departure lounges and the staff all look like airline staff. The pilots wear white shirts and bars and even ties.
One could forgive them for thinking that the regulations afford them the same protection that they enjoy when flying in a Saab 340 or Beech 1900, for instance (both many times cheaper than an EC-155 or S-76), but no that is not the case.
Instead, the manufacturer says to the regulator "look, it's too hard to do this and costs too much. Why don't we say that for 9 seconds during take off, if an engine fails, we have no idea what will happen to the aircraft and if there are hard immovable objects in the way, well that's just a statistical risk we can take based on creative use of past engine data failure." "oh, and by the way, can we ignore things like governor run downs as they're not really engine failures are they? Oh, and this is a new engine airframe combination, so we don't have a real data set, so guess what; the results are skewed!"
Great! That's progress! Performance is pretty marginal anyway without degrading it further.
I fully accept that the flexibility of this aircraft places it in many varied situations where the crew and other personnel (long lining, power line patrols, SAR etc) are in some risk. However they know that and accept it. What I disagree with is the idea that we can legislate the exposure concept for onshore commercial air transport with fee paying, ignorant (in the literal sense!) members of the public.
Last edited by 212man; 12th Aug 2004 at 16:48.
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I have one question for everyone. Why must pilots in the gulf of Mexico fly twin engines equipment with a fuel requirement of destination plus 30 minutes, and not enough power to land on any rig or platform with one engine inopertive, and not enough fuel to go to the beach. Ditching in the water in not a normal procedure. So far no one has had to do this. The only aircraft that has the power to hover at gross wt with one engine , is the Bell 214ST, and it is a dinosaur. I vote to have more powerful engines.
Thanks for letting me get this off my chest.
Thanks for letting me get this off my chest.
Nick said:
"and also that such full Cat A would not increase the actual safety of the operation, as long as limited exposure rules were applied."
Again, quite correct. Full Cat A availability is a only as good as the pilot on the end of the controls. You can have all the engines in the world but without the correct profile flown it is a waste of time. You still end up in the side of the rig, ocean or the side of the hospital in EMS.
More exposure to single engine operation in the training regime and education on correct approach and departure techniques would be many times more worthwhile.
An S76A can be flown at pretty much MAUW on a profile that will allow a single engine landing with no roll out on a rig or roof top. Take offs are another issue.
"and also that such full Cat A would not increase the actual safety of the operation, as long as limited exposure rules were applied."
Again, quite correct. Full Cat A availability is a only as good as the pilot on the end of the controls. You can have all the engines in the world but without the correct profile flown it is a waste of time. You still end up in the side of the rig, ocean or the side of the hospital in EMS.
More exposure to single engine operation in the training regime and education on correct approach and departure techniques would be many times more worthwhile.
An S76A can be flown at pretty much MAUW on a profile that will allow a single engine landing with no roll out on a rig or roof top. Take offs are another issue.
DECK EDGE
Nick…you do know how to “stir the pot”……….but an excellent subject. I must agree that with a limited purse , one must prioritize what goodies one can buy. So I have no argument with you there.
HOWEVER , on the specific subject of engine failure at the rig , may I direct the issue to a helicopter’s ability to fly a profile that will allow a successful escape after the engine has quit. By successful , I mean survivable.
(Bear in mind that I am currently flying the A model 76 in the tropics.)
Now I am not as concerned with the landing phase. With good technique , even hot and nil wind , an engine failure on approach , holds less angst for me. It is the take off that worries me….and surprise surprise …. it is NOT the single engine performance that I want , it is TWIN performance ! WHY ?
I lost an engine on rotation from a rig many years ago. It was not a Sikorsky but the lesson was indelibly imprinted on my brain. We rotated at about 15 feet. Our event was witnessed by the rig radio operator. The PT6 (well that is a bit of a clue) spat half the turbine out the back , right on rotation. We did fly away but the radio operator verified what really scared the crap out a me... and that was that the tail rotor cleared the deck edge by inches. Now had I hit the deck edge with the T/R then OEI performance , or even Twin performance becomes academic….I am dead meat.
So that is what I mean by wanting TWIN PERFORMANCE. I want to be able to lift high enough so that if I do lose an engine at that critical point on rotation , I can clear the deck edge and either fly away or ditch.
I see that the C+ does have various profiles/performance graphs for drop down , fly away etc from an elevated helipad (ie helideck). I have not flown the C+ in traditional offshore oil operations so am very curious about the profiles that offshore C+ OPERATORS are using and their subsequent WAT limits. Are they equipped with the collective detent system that EAA has ?? etc etc
Finally , I would very much like to have 100% Cat A , but if I can’t ( for whatever reason) then give me twin engine performance AND a profile that allows me to escape that deck edge after an engine quits.
Great subject.
Peter
HOWEVER , on the specific subject of engine failure at the rig , may I direct the issue to a helicopter’s ability to fly a profile that will allow a successful escape after the engine has quit. By successful , I mean survivable.
(Bear in mind that I am currently flying the A model 76 in the tropics.)
Now I am not as concerned with the landing phase. With good technique , even hot and nil wind , an engine failure on approach , holds less angst for me. It is the take off that worries me….and surprise surprise …. it is NOT the single engine performance that I want , it is TWIN performance ! WHY ?
I lost an engine on rotation from a rig many years ago. It was not a Sikorsky but the lesson was indelibly imprinted on my brain. We rotated at about 15 feet. Our event was witnessed by the rig radio operator. The PT6 (well that is a bit of a clue) spat half the turbine out the back , right on rotation. We did fly away but the radio operator verified what really scared the crap out a me... and that was that the tail rotor cleared the deck edge by inches. Now had I hit the deck edge with the T/R then OEI performance , or even Twin performance becomes academic….I am dead meat.
So that is what I mean by wanting TWIN PERFORMANCE. I want to be able to lift high enough so that if I do lose an engine at that critical point on rotation , I can clear the deck edge and either fly away or ditch.
I see that the C+ does have various profiles/performance graphs for drop down , fly away etc from an elevated helipad (ie helideck). I have not flown the C+ in traditional offshore oil operations so am very curious about the profiles that offshore C+ OPERATORS are using and their subsequent WAT limits. Are they equipped with the collective detent system that EAA has ?? etc etc
Finally , I would very much like to have 100% Cat A , but if I can’t ( for whatever reason) then give me twin engine performance AND a profile that allows me to escape that deck edge after an engine quits.
Great subject.
Peter
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Nick
You make the point about turbojets having ample thermodynamic power at low altitudes as a result of their design requirement to be able cruise much higher. Can a similar design concept be applied to Helicopters. That is, designers set performance goals to the aircraft based on a cruise height eg 10,000 feet (no oxy) and say we want max OEI payload, maintain height (dont worry about using driftdown techniques), suffer only a 10% loss of TAS, full anti ice & heater on (I hate being cold). From this then surely the flow on effect would be helicopters with engines of similar power excess and thus "CAT A" for free.
The selling point could then be related to cruise safety, performance and comfort and "hey we can even land and takeoff on one engine but we will throw that in for free".
In the fixed wing (jet/turboprop) world you lose an engine and you usually still get to where you were going or end up back where you started, but with helicopters generally you dont as they lose so much cruise performance that an intermediate alternate is required, this is most felt in the medium twin market.
Anyway IMHO engine power is a bit like diet coke you can never have too much, nothing like being able to lift heavy things I say.
You make the point about turbojets having ample thermodynamic power at low altitudes as a result of their design requirement to be able cruise much higher. Can a similar design concept be applied to Helicopters. That is, designers set performance goals to the aircraft based on a cruise height eg 10,000 feet (no oxy) and say we want max OEI payload, maintain height (dont worry about using driftdown techniques), suffer only a 10% loss of TAS, full anti ice & heater on (I hate being cold). From this then surely the flow on effect would be helicopters with engines of similar power excess and thus "CAT A" for free.
The selling point could then be related to cruise safety, performance and comfort and "hey we can even land and takeoff on one engine but we will throw that in for free".
In the fixed wing (jet/turboprop) world you lose an engine and you usually still get to where you were going or end up back where you started, but with helicopters generally you dont as they lose so much cruise performance that an intermediate alternate is required, this is most felt in the medium twin market.
Anyway IMHO engine power is a bit like diet coke you can never have too much, nothing like being able to lift heavy things I say.
I shud have read JimL's more thoroughly....agree agree agree
also like his following comment...
"It has become increasingly clear that ‘standards’ are within the bailiwick of the customer and not the operator"
and aint that the truth but also a double edged sword.
also like his following comment...
"It has become increasingly clear that ‘standards’ are within the bailiwick of the customer and not the operator"
and aint that the truth but also a double edged sword.
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Well, it seems the technical information is all available. The operators that fly helicopters because their start and/or end points aren't runways, seem satisfied with the limited exposure argument. The operators that spend a significant amount of time in the hover seem to want the OEI performance.
That doesn't surprise me. However, in the end, helicopter design is not about what can be done or what is desired, but what can be sold. Regulations not conscience are the forebearer of safety, so until the regulations are in place, I doubt any operator is willing to pay the huge cost of providing this safety performance.
I think a helicopter company should design a twin that outperforms 412, 76, etc. in their typical roles, and has full envelope OEI. Before marketing this machine, the company should lobby all the regulatory boards and insurance companies to demand this. Then us poor operators would be left with no choice but to fly safe expensive machines.
Seriously though, I have no problem with a limited exposure argument as long as the mission can be flown as such. Use a very long line, a light helicopter, etc. I can't think of anyway of making SAR any safer since a higher hover means more time with a man on the hoist...injury more likely than an engine failure. Although we do try to give ourselves time to 'drop' the man, cut cable and fly away.
Matthew.
That doesn't surprise me. However, in the end, helicopter design is not about what can be done or what is desired, but what can be sold. Regulations not conscience are the forebearer of safety, so until the regulations are in place, I doubt any operator is willing to pay the huge cost of providing this safety performance.
I think a helicopter company should design a twin that outperforms 412, 76, etc. in their typical roles, and has full envelope OEI. Before marketing this machine, the company should lobby all the regulatory boards and insurance companies to demand this. Then us poor operators would be left with no choice but to fly safe expensive machines.
Seriously though, I have no problem with a limited exposure argument as long as the mission can be flown as such. Use a very long line, a light helicopter, etc. I can't think of anyway of making SAR any safer since a higher hover means more time with a man on the hoist...injury more likely than an engine failure. Although we do try to give ourselves time to 'drop' the man, cut cable and fly away.
Matthew.
First in answer the question posed by Mars on the EC225 thread:
Within the extant JAR-OPS 3 (amendment 3 at 1st April 2004), approval to operate with exposure to an engine failure on take-off and landing lapses from 2010 and operation in Performance Class 1 (PC1) will be required. For a number of reasons (mainly concerned with the deck size and the helideck environment – both obstacle and wind related), it is not anticipated that operations in Performance Class 1 will be technically feasible or economically justifiable by that time (One Engine Inoperative (OEI), Hover Out of Ground Effect (HOGE) would be an acceptable method of compliance but this could result in a severe restriction on payload/range).
In view of this approaching deadline and the limitations discussed above, there is a need to produce a practical alternative to PC1 which will ensure that take-off/landing mass reflects: the procedure; deck-edge miss; and drop down. As accident/incident data indicates that the main hazard is collision with obstacles on the helideck due to human factors, a simple and reproducible but deterministic procedure is required. Such a procedure will require the calculation of the take-off/landing mass from information produced by manufacturers reflecting these elements. It is expected that manufacturers information will be derived from performance modelling/simulation using a model validated through limited flight testing. This alternative to PC1 for offshore operations might be termed Enhanced Performance Class 2 (PC2e).
This subject, as a debate, was concluded some year ago and led to guidance that take-off from a helideck should only be undertaken with hover out of ground effect performance (all-engines-operating). It should be clear to all that as soon as the ground cushion is dissipated the aircraft will sink - all of us who have flown the early marks of the S76 in nil wind conditions will sympathise with your post.
It is a commonly held belief that we have more problems with power for take-off than for landing; performance modelling does not accord with this thinking and appears to indicate a greater power requirement for landing than for take-off. If one were to examine the masses for the S76C+ helideck Cat A take-off and landing, it would confirm the modelling results; however, this statement should be hedged around with qualifications as it results from an interpretation of JAR 29 that appeared to require that a single-engine landing should be possible on the helideck with a failure occurring at any stage in the approach. Perceived wisdom, confirmed by performance modelling, appears to confirm that providing Risk Assessed landing profiles are flown, the gap between take-off mass and landing mass can be narrowed. In partial answer to ‘gomex’s’ comment, such profiles are dependent upon a OEI flight back to a land base. I’m sure Nick will wish to comment on these thoughts.
Perhaps you might wish to follow the thread on the AB139, which appears to have this capability. With regard to your comment on lobbying, you will see that there is an attempt to describe the level playing field that you demand contained in the first two paragraphs of this post.
None of us could have stated this better, if operational margins are to be limited to permit techniques which do provide engine failure accountability at an economically justifiable cost (be it PC1 or PC2e), the success of these techniques will be wholly dependent upon: (1) an understanding by the pilot of the risk profile of the technique; and (2) adherence by the pilot to that profile.
For the reasons discussed in the comment to Peter, this statement is not borne out by modelling or practical experience; whilst it may be possible to demonstrate this to a “landing square” that is drawn out on a runway, it is generally accepted by test pilots that this is not true when flying to an elevated heliport or helideck.
Within the extant JAR-OPS 3 (amendment 3 at 1st April 2004), approval to operate with exposure to an engine failure on take-off and landing lapses from 2010 and operation in Performance Class 1 (PC1) will be required. For a number of reasons (mainly concerned with the deck size and the helideck environment – both obstacle and wind related), it is not anticipated that operations in Performance Class 1 will be technically feasible or economically justifiable by that time (One Engine Inoperative (OEI), Hover Out of Ground Effect (HOGE) would be an acceptable method of compliance but this could result in a severe restriction on payload/range).
In view of this approaching deadline and the limitations discussed above, there is a need to produce a practical alternative to PC1 which will ensure that take-off/landing mass reflects: the procedure; deck-edge miss; and drop down. As accident/incident data indicates that the main hazard is collision with obstacles on the helideck due to human factors, a simple and reproducible but deterministic procedure is required. Such a procedure will require the calculation of the take-off/landing mass from information produced by manufacturers reflecting these elements. It is expected that manufacturers information will be derived from performance modelling/simulation using a model validated through limited flight testing. This alternative to PC1 for offshore operations might be termed Enhanced Performance Class 2 (PC2e).
Peter Manktelow -
Now I am not as concerned with the landing phase. With good technique , even hot and nil wind , an engine failure on approach , holds less angst for me. It is the take off that worries me….and surprise surprise …. it is NOT the single engine performance that I want , it is TWIN performance !
Now I am not as concerned with the landing phase. With good technique , even hot and nil wind , an engine failure on approach , holds less angst for me. It is the take off that worries me….and surprise surprise …. it is NOT the single engine performance that I want , it is TWIN performance !
It is a commonly held belief that we have more problems with power for take-off than for landing; performance modelling does not accord with this thinking and appears to indicate a greater power requirement for landing than for take-off. If one were to examine the masses for the S76C+ helideck Cat A take-off and landing, it would confirm the modelling results; however, this statement should be hedged around with qualifications as it results from an interpretation of JAR 29 that appeared to require that a single-engine landing should be possible on the helideck with a failure occurring at any stage in the approach. Perceived wisdom, confirmed by performance modelling, appears to confirm that providing Risk Assessed landing profiles are flown, the gap between take-off mass and landing mass can be narrowed. In partial answer to ‘gomex’s’ comment, such profiles are dependent upon a OEI flight back to a land base. I’m sure Nick will wish to comment on these thoughts.
Heedm - I think a helicopter company should design a twin that outperforms 412, 76, etc. in their typical roles, and has full envelope OEI. Before marketing this machine, the company should lobby all the regulatory boards and insurance companies to demand this. Then us poor operators would be left with no choice but to fly safe expensive machines.
Steve 76 - Full Cat A availability is a only as good as the pilot on the end of the controls. You can have all the engines in the world but without the correct profile flown it is a waste of time. You still end up in the side of the rig, ocean or the side of the hospital in EMS.
Steve 76 - An S76A can be flown at pretty much MAUW on a profile that will allow a single engine landing with no roll out on a rig or roof top. Take offs are another issue.
CAT A, peformance class 1
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alouette:
It is difficult from your profile to know on what geographical basis you are asking this question but, if you are asking on a European basis, there are two questions you need to ask:
The answer to my second question and your only one; yes, it does have a number of approved Category A procedures.
It is difficult from your profile to know on what geographical basis you are asking this question but, if you are asking on a European basis, there are two questions you need to ask:
- Is the Bo105 certificated for Category A; and
- Does it have approved Category A procedures in its flight manual
The answer to my second question and your only one; yes, it does have a number of approved Category A procedures.
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BO 105
To Mars:
Maybe I should have specified my question. It is more like is the BO 105 capable to operate in performance class 1 lets say at 35C OAT? Fire fighting? With HUMS installed, etc... Thanks
Maybe I should have specified my question. It is more like is the BO 105 capable to operate in performance class 1 lets say at 35C OAT? Fire fighting? With HUMS installed, etc... Thanks
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alouette:
That's a length of string question and I'm still not sure of your motives; why don't I attempt to answer the question that I think you are asking and we can continue from there.
The ability to perform any Category A procedure will be limited at some combination of density, payload, fuel etc. Depending on the procedure the limit will come sooner or later; the helipad procedure will limit earlier than the short field, will limit earlier than the clear area (runway).
Shawn referenced the case where it was safer putting a worker into a position with a helicopter than it was for him to climb up - this is sometimes called the 'Relative Safety Case'. However, it does depend upon the State of Operation whether that particular operation would be permitted with other than OEI OGE hover performance - it is likely in the UK that the higher performance standard would be required. Even though that particular operation is not within a Category A procedure it could be regarded as equivalent to PC1 as engine failure would have been accounted for.
Other Aerial Work tasks would not have the protection of such performance - the risk of engine failure is accepted in view of the fact that there is no exposure for passengers or third parties. Fire fighting comes into this category. There are no performance standard requirement for Aerial Work
I am not certain what you mean by HUMS but, for the purpose of this discussion let us assume that you mean engine monitoring such as that provided by Monitair or Altair (UMS). If all operations were to be in PC1, engine failure would have been accounted for and so there would be no need for engine monitoring. In the event that Commercial Air Transport (CAT) PC2 operations ‘with exposure’ were being contemplated, there might be a requirement depending upon the regulation - for example when operating in accordance with JAR-OPS 3.
If you genuinely do mean HUMS, it is likely that this would be a combination of UMS and vibration Health Monitoring (VHM) - which is only now coming over the horizon and is mainly being considered to address tail rotor failure issues.
In any event, it is unlikely that either of these pieces of equipment will add greatly to the weight of the Bo.
I am not a Bo105 expert and I’m sure that others can answer any specific question you have on Category A take-off masses - it is normal Flight Manual fare.
That's a length of string question and I'm still not sure of your motives; why don't I attempt to answer the question that I think you are asking and we can continue from there.
The ability to perform any Category A procedure will be limited at some combination of density, payload, fuel etc. Depending on the procedure the limit will come sooner or later; the helipad procedure will limit earlier than the short field, will limit earlier than the clear area (runway).
Shawn referenced the case where it was safer putting a worker into a position with a helicopter than it was for him to climb up - this is sometimes called the 'Relative Safety Case'. However, it does depend upon the State of Operation whether that particular operation would be permitted with other than OEI OGE hover performance - it is likely in the UK that the higher performance standard would be required. Even though that particular operation is not within a Category A procedure it could be regarded as equivalent to PC1 as engine failure would have been accounted for.
Other Aerial Work tasks would not have the protection of such performance - the risk of engine failure is accepted in view of the fact that there is no exposure for passengers or third parties. Fire fighting comes into this category. There are no performance standard requirement for Aerial Work
I am not certain what you mean by HUMS but, for the purpose of this discussion let us assume that you mean engine monitoring such as that provided by Monitair or Altair (UMS). If all operations were to be in PC1, engine failure would have been accounted for and so there would be no need for engine monitoring. In the event that Commercial Air Transport (CAT) PC2 operations ‘with exposure’ were being contemplated, there might be a requirement depending upon the regulation - for example when operating in accordance with JAR-OPS 3.
If you genuinely do mean HUMS, it is likely that this would be a combination of UMS and vibration Health Monitoring (VHM) - which is only now coming over the horizon and is mainly being considered to address tail rotor failure issues.
In any event, it is unlikely that either of these pieces of equipment will add greatly to the weight of the Bo.
I am not a Bo105 expert and I’m sure that others can answer any specific question you have on Category A take-off masses - it is normal Flight Manual fare.
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Take care with the simple question about Cat A or not Cat A. Every twin can have a full Cat A envelope, but for most, the reduced gross weight for the full Cat A means almost no payload. The real question is at what cost to payload/range/economics is full Cat A?
I will try to post some influence charts to illustrate the issue of payload vs landback distance and range vs OEI engine power, where it is the physics of the helo that cost the awesome price, not just lazy designers or cheap operators.
I will try to post some influence charts to illustrate the issue of payload vs landback distance and range vs OEI engine power, where it is the physics of the helo that cost the awesome price, not just lazy designers or cheap operators.