Nick says
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The US Army's experience with the GE T700/CT7 engine family is very impressive: the failure rate is 1 engine failure per 500,000 hours of engine operation for engine cause, and 1:200000 for all causes (mostly pilot/fuel issues.) At 1:200,000 hours, that means a 500 aircraft civil fleet flying 1,000 hours per year per aircraft would experience 5 engine failures per year total, and 2 that were the engine's fault. If the average mission is 1 hour long, and there was an 8 second exposure time on takeoff, and a 5 second one on landing (13 seconds out of 3600) then the fleet spends 0.36% of its life in the exposure zone. This infers an engine failure every 55 years inside the exposure time!
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Am I correct to assume that an engine is more prone to failure when operating at very high power demands? Like during T/O, Ldg and hovering? On some twins the T/O Cat A profile requires 100% torque. What are the statistics for engine failure at max power? The thread was, after all, about take off and landing performance.

The Cat A profiles also require an engine to be able to produce it’s published power. How many engine changes has the Sikorsky 76C+ fleet had because of failure to meet the PPI?

My point is the engines on a lot of twins are operating very close to their design limits. Would it not make sense to have some margin in these engines in order that they are not at max chat at every take off? That margin could then be used to reduce the exposure time and reject distance in the event of OEI. I know we have OEI 30 sec and 2.5 min limits but utilizing these margins, on some twins, still requires 100’s of meters of flat unobstructed reject area and a replacement of the good engine if it all works out.


Helmut fire says

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It is simple: operate to the appropriate risk exposure you are willing to accept AND pay for. If that means you have 5 people to transport with PC1 risk, then you will have to get out of your AS355 and pay for a 412. If you have 13 people for a PC1 op, then get out of your 412 and into the 332
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Most light twin helicopters were designed to carry 12 pax. In the Corporate role most of these helicopters are fitted for just 6 pax. And still we struggle to get airborne and fly 250 miles. We don’t struggle from airfields but from the operating sites. Yes, I know, we can get rid of the leather, the bar, the A/C and all the other luxuries but the boss likes them!
And the Helicopter Manufacturers like selling them!


Mars says:

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How can the manufacturers be accused of hiding performance, don’t they publish the Category A procedure; isn’t it more that the operators, pilots and regulators are not capable of asking the correct questions and appear to be satisfied by a statement that the aircraft is Certificated to Category A.
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I did not say that they hide their performance figures. The words "Category A" sell helicopters that have insufficient performance for a lot of corporate and charter operations.

Can hardly wait for the AB139 and the Grand!

FLI:

It was meant to be irony and make exactly the point that you were making. Why would anyone buy a helicopter without establishing exactly what it can and cannot do - performance wise? Is it that we helicopter pilots do not understand the issues?

FLI,

No, I think it is generally incorrect to assume that power margin is the way to assure engine failure reliability. Those military engines I note are used in awful environments by Army pilots and mechanics, and the stats are what they are, anyway. The way to assure flight safety is to fix the cause of accidents, FLI, not to add more engine power, but you miss all that, and fail to even consider it.

I note that the numbers don't move you at all, you gloss over the proven experience that there are about 9999 more ways to have an accident than an engine failure in a critical exposure window, ways that get us every day, in spite of the exposure windows we have.

You seem upset about all this, and blame lots of people for your plight. You have choices. Carefully note the cost to operate, the payload, range and OEI peformance, and buy what you want, of course. When you do find the perfect ground level, zero exposure helicopter, do not be disappointed to find the IFR range is a bit shy, and the costs are equivilent to those of an aircraft that carries a bunch more payload, since you are really buying a given helo, and operating it at 75% of its potential.

And for accident prevention, please buy an EGPWS with that new machine!

Nick,

I think you already know that most corporate machines bought from Sikorsky are very well equiped with the aids to flight safety that you list. I am very grateful to Sikorsky for developing and providing them.

But, the issue here is power. Not just OEI but twin engine power.

Apart from the 'B model' the 76 just doesn't have enough power.

Eurocopter's 155 has similar limitations.

The topic of this thread was "full Cat A?" Yes, there is a market for it.

I'm just glad that another manufacturer is addressing that!

FLI touches on the points I raise quite nicely, but so far no one seems to really appreciates the full significance of onshore PC2 exposure time as a concept. We are not talking about using 332s to lift 412 cabin loads etc, we are talking about using using class 2 performance criteria to take off from a site where in fact there is no suitable reject area for a significant portion of the take off profile.

Nick, I appreciate what you are saying but please also remember that what we have to operate to, regardless of the client or operator, is some logical and justifiable arena of operation that we can justify to the proverbial "subsequent board of enquiry." Generic discussion of engine reliability does not hold sway in court; regulatory documents will.

FLI,
In supporting your point about Cat A, you say, "I'm just glad that another manufacturer is addressing that!" as if one or the other manufacturer is represented here, or as if one or the other does not provide what you are looking for.

Let me state again, the opinions I state here are mine, and not a line from any company. To infer otherwise is not correct, and frankly unfair.

I believe that all manufacturers provide helos that meet full Cat A from rigs, ground level heliports and anywhere else. The charts that tell you how to perform to those standards are in the flight manuals.

212man,
I guess you are bound to hard Cat A, am I right? If so, there are good procedures for this for virtually all aircraft.

FLI and 212man,

My point was that performance IS linked to dollars. If you want more margin then the upgrade will cost more $$. What about all those other operators who are comfotable with the current margins due to their risk profiles? Do we make them pay for the extra margin and affect their economic viability? Surely it's better the way it is now - that those who want the extra margin due to their risk profiles CAN access it by either operating with reduced payload or buying a bigger machine. If the bosses like their leather - then that comes at a cost of exposure. They can forgo the nice bits OR buy a bigger machine: at least they have an option.

Nick, on the fuel dump I agree that the critical issue part is the dip down, and as I said, it will not solve your deck edge clearance issues, but that is, as you point out, such an insignificant period of exposure. The dump pipe WILL benefit you over the entire rest of the exposure envelope with the exception of final landing stages. So taking Nick's 0.36%, that is during 99.64% of the flight time, a fuel dump pump will be of benefit to OEI situations.
A slightly unfair use of stats, but you get the point. Maybe thats your answer FLI: stay with the leather, add a fuel dump.

Nick...we have been this way before....ok I have the OGP pie charts now and I am convinced about CFIT. Elimate that section of the chart and you take a great chunk out of your risk exposure.

Cant afford the EGPWS and dont think it is value for money in my environment where I operate literally from the beach ie 99% of my flight is over water (typical offshore oil support) where Radalt/Radar/GPS AND sound procedure should ( I say should)keep me outa the water or from hitting the rig. (is not striking the deck edge post OEI take off , sort of CFIT ?? sorry , a touch of Aussie "stirring" creeping in there.)

anyhow....

CFIT training is not readily available unless one makes up their own course and then , as far as I can see , it is still a classroom exercise. I sure would like to see what other people have done in the way of CFIT training..in the classroom/aircraft/WPB Simulator

Peter:8

peter, peace! The right procedures and awareness should serve, but at the next equipment upgrade.....


Here is some stuff to whet the argument. I did a small design exercise, crude but to the point:
Here are three similar helos, all the same gross weight, same rotor and such, but they differ in engine power. the single has one 1300 HP engine, the middle twin has two 700HP engines and can do airport OEI procedures, and the third has two 1000HP engines, and can Hover OEI.


http://www.s-92heliport.com/table.jpg

Note that the payload and range are vastly different, mostlt because of the extra gross weight and the extra fuel flow.
http://www.s-92heliport.com/payload.jpg

Note that the sacrifice for OEI hover is pretty big.

Here are two OGP pdf files for us to chew on, great stuff, thanks to some great helo pilots who work for the Oil Companies, and who really try to do the right thing. Each file is not quite 1 meg:

http://www.s-92heliport.com/OGP1998.pdf
http://www.s-92heliport.com/OGP2002.pdf

Nick, Eurocopter & Airfix

With lives at stake daily and the need to hover in all sorts of wonderful places, weather and altitudes. The big twin is going to be the choice of the SAR pilots. We would gladly sacrifice a little max range and payload (no commercial penalty for us). We are frequently exploring the boundaries of possible OEI territory for protracted periods. The great threat of CFIT for us is a very real. Escaping it on one engine that insists on taking you to the scene of the accident isn’t acceptable when an EGPWS is ‘whooping away’. Granted engine failures are rare and with the increased protection afforded by modern design, we will be better placed with the newer EC & Sikorsky products. Albeit limited for now, the SAR world is a growing market. ‘Loads of power’ please.

Helmet,

Fuel dump is an excellent device when a helicopter cannot meet its en-route performance - for example where it has to clear a defined obstacle (a mountain peak). Guidance on this is contained in JAR-OPS 3, IEM OPS 3.500(a)(5) - suffice to say that the fuel remaining after the dump must meet the requirement for continuation to a destination or alternate (i.e. the use of dump must be planned before take-off - as it always was when being used in the S61).

The maximum take-off mass for operations in PC2 is defined by the second segment climb (150ft/min OEI at Vy - 1000ft above the take-off point); this second segment climb is identical to the requirement for PC1. This leads to a number of observations:

Ipso facto the extent of exposure (when permitted) will be defined by one of the above. Take-off distances will always be less for PC2 as they can be calculated AEO; unlike PC1 where they have to be calculated OEI.

Nick can provide the time/distance for most of the above but from experience, it is not likely to be more than 10 seconds from the time that all-engines-operating acceleration is commenced (be it from the hover or from the rotation point at the top of the vertical section of the take-off profile).

None of this can possibly be influenced by a fuel dump - which under civilian operating rules, cannot be commenced below 1000 ft.

Nick, you say “I believe that all manufacturers provide helos that meet full Cat A from rigs, ground level heliports and anywhere else. The charts that tell you how to perform to those standards are in the flight manuals”.

When you started this thread, you were discussing “hard core Cat A”. We now appear to be discussing the Cat A profiles that have been in helicopter manuals for many years. Most of these profiles require unrealistic onshore, off airfield, rejected T/O areas or substantial reductions in payload. Yes, as pilots, we have choices but sometimes the field conditions just do not allow us to be so flexible.
Regulations often provide no flexibility.
Even after a full site recce in preparation for a flight, conditions can change. In the UK this summer, we have had +17 one day and two days later it is +30! Welcome to England! We have to reduce payload (leave the boss’s wife behind?) or stop enroute to fuel or even cancel the flight. Hardly “all weather Cat A” that the manufactures put in their glossy publications. We can’t even fly on sunny days! Reliable door to door time is why the clients bought the machine.

With regards to limited range, most corporate clients have access to jets. They generally do not fly 400 miles by helicopter. They go by jet. Give us 2.5 hours fuel with an aux tank option to extend to 3 hours.

When Sikorsky produced the B model, they answered a lot of the performance failings of the A. Yes, the fuel consumption was a lot more and the range reduced, but Sikorsky offered an aux tank option to redress these issues and increase the flexibility of the machine. For many years the B cornered the corporate market, with clients switching from A’s and AS365’s. What a sad day it was, when Sikorsky closed the B production line and introduced the C. Some very wealthy clients are now flying in 15 year old B’s because there has been no comparable alternative, performance wise. The large twins are just too large for many public-use sites.

When Eurocopter announced the 365N4 (to become EC155B) many clients were excited. In reality, the marginal performance of the 155B was quickly addressed with the introduction of the B1. (It went from marginal to weak). Lovely aircraft to fly, just poor performance. It has Cat A certification.

Early versions of the Explorer did not have enroute Cat A performance (level sustained flight OEI) at realistic range/payload. Addressed for later versions.

We all remember early versions of the 109… full fuel no pax or full pax no fuel! Again, addressed for later versions.

It is ironic that, most ‘full pax and full fuel’ helicopters are single engine and that they require less distance for a RTO than many so called Cat A twins!

212man has highlighted the regulatory issues very well.

Helmut fire says “Maybe that’s your answer FLI: stay with the leather, add a fuel dump”. I have flown aircraft with fuel dump. How will it help during the critical T/O phase? I hardly think you would have time, or the inclination, to spray fuel during an OEI reject! If one is able to take off Cat A then, generally, one has Cat A enroute performance in most helicopter operations. It is would be useful to reduce weight for the OEI landing but the critical power phase is during T/O.

What I find most ironic from some of the postings is, now that we are close to getting “Hard Core Cat A”, people are questioning the requirement. Ask any onshore twin engine helicopter pilot operating commercially if he needs/wants more power to satisfy safety and regulations.

FLI,

You have not moved from your starting point. You have not recognized the accident probabilities. or the cost in reduced range and payload of providing the amount of excess power. You have basically blamed those "misleading" manufacturers with the "glossy brochures", who seem to be unable to break the laws of aerodynamics enough to suit your needs.

But you are stating that you want, need, and insist on - full Cat A, and that is fine. You havn't accepted the fact that this will reduce other aspects of the design. You do know there is a design trade off at work, when you state, "It is ironic that, most ‘full pax and full fuel’ helicopters are single engine....."

See the above charts that explain how big-engined twins have LESS payload and range than equivilent singles.

The question on the table is not "How much OEI power do you want?" The question is, "What range, payload and safety benifits are you willing to give up to gain that OEI power margin?"

Nick:

Whilst most of us can contemplate a rational discussion of PC2 v PC1 in areas where there are no third party risks; and, under some circumstances, measure the arguments for and against PC2 ‘with exposure’ - the fact that a single can lift more than a twin is a non sequitur.

We are straying from a discussion of whether it is technically feasible and economically justifiable to eliminate/limit exposure to engine failure in the take-off and landing phases to one where the flight is always exposed to an engine failure. I’m not sure FLI’s customer base will welcome the improvement in range that is based on swapping two engines for one.

As has been pointed out in recent posts, PC2 with exposure is limited in time and space and could be part of a Risk Assessed departure/arrival regime - we (with some certainty) know: the maximum extent of the exposure; the probability of engine failure; and can assess the consequences of that failure; both in immediate terms for this phase, and in the medium and long term on our business (be it a one-man-band or a multi-national oil company).

What comes as a surprise to all of us is not ‘driving looking in the rear view mirror’ but the attempt to ‘put the car into reverse’. We already know that the EC225, AS332L2, S92 and S76 can operate in PC1 and to their credit the latest marks of the EC135, A109, MD902 and AB139 can do it in spades.

FLI may have not moved from his starting point - he knows what his customer wants; what is puzzling us is the direction of your movement.

Nick,

I think you will find that I have acknowledged the other aids to flight safety. I have acknowledged the reliability figures. I did, however, question the validity of the figures when discussing very high power demands. I have accepted that there will be a trade off in range and payload.

What I fail to understand is why we, the operators, must accept unrealistic onshore RTOD.

Most of your arguments are counter to Sikorsky ever producing the B model to provide an alternative to the ‘A’. The number of onshore operators using the ‘B’ is testament to accepting the trade-offs for more performance. (Less range, less payload, higher costs, etc.) The same argument applies to the AS365N, N1, N2 and N3. The answer, I suspect, is in response to customer requirements for more power.

Yes, I understand the penalties of a reduced RTOD. Anyone who has flown twin anything will recognise the trade-offs. It is there in the charts.

My issue is that all twin engine helicopter manufactures provide ‘Cat A’ but in a lot of circumstances the penalties are too great to operate full Cat A. We need more power to reduce/eliminate the RTOD.

Legislation, particularly operations within congested areas, requires full Cat A. On many of the helicopters today that is nigh on impossible without a very substantial reduction in payload. Perhaps, instead, we should be lobbying for a relaxation of the rules based on the industry statistics? Maybe, even, fly medium singles as they appear to answer a lot of the problems that the manufactures have in providing what we want?

Those cost conscious operators can continue to fly today’s machines. Let the corporate/onshore charter customers have an alternative to the ageing 76B!

As an aside, I have suffered 4 engine shutdowns on twins: Two in the cruise to secure an engine due to low oil pressure, one in the hover due to no oil pressure (burst pipe) and one engine explosion during take off. I have also had governor problems, which, not technically an engine failure, have resulted in limited power landings. So much for statistics! Touch wood, none on singles though!

Mars and FLI,

Sorry that my post was so misunderstood, as I have tried to show the natural progression in cost to the design from 1 to 2 smaller to 2 big engines. This is a free ranging discussion, and I am just painting the picture of how the cost builds. Note the reasonably symmetrical damage to range and payload as the single morphs to a twin with Cat A enroute to the very capable twin.

I note with both you and FLI take it as a given that more engine OEI power is better, safer and more modern, so you have made your minds up. Fair enough, but I am not sure why you believe it is safer, you never told us. That was the reason for the thread!

Nick, if you think "I'm hardcore Cat A" you want to come and look at my operating environment! Especially in an a/c that drops Cat A weight from 19.5 C at sea level, and operating in the tropics.

It's too late at night to come up with long answers to discuss the points that you and JimL et al raise, so I won't try.

Please don't raise the issue of what the military do and do not accept as a risk for AEO/OEI ops: clearly they have a different agenda and evaluate risk from a different perspective. They also have a different legal liability exposure too.

I fully accept the basic premise of PC2 ops as a concept (or I wouldn't be operating onshore with water rejects!) As I have tried to say, though, the idea of adding the exposure time concept to onshore ops is (IMHO) a backwards step that is not well understood by many pilots or, especially, the passengers.

As I understood it, the frangible parts were supposed to be on the aircraft or the landing surface; not pink, soft and within the cabin!

Anyone got any figures for a 214B with a 412 head? That must be the way forward, surely?

FLI: do you read the responses? Look for your point about the fuel dump on the take off part in both my posts. Is there an echo here somewhere? Whilst you highlight the lack of brainspace available to the pilot during an OEI on take off, I note that floats and contingency power limiter switches have previously been incorporated and successfully used in the past despite such brainspace issues.

The point was that the fuel dump is not effective on the rejected take off, nor after the TDP, but it is usefull for the other 99.64% by giving you a much improved power margin for your subsequent actions. You want the power margin - and a fuel dump will give that to you. Not only does it provide you better enroute planning ability due to the ability to significantly increase drift down altitudes, it provides you a significantly better margin when you try to land OEI, but it also gives you an improving margin in your OEI flyaway attempt after TDP. And if you correctly pick your flight path (avoiding disabled kindergardens and day care centres), a fuel dump below 1000ft AGL is justified in an emergency.

So, to incorporate a fuel dump into your risk management process, you will take off 60lbs heavier, thus you should climb a bit extra for the TDP, and increase LDP. For that 0.36% of the sortie you will land 60lbs heavier in your OEI situation, but between TDP and LDP you will have a power margin increase and thus a reduced risk exposure over the remaining 99.64% of the sortie, and it may even allow you to accept higher enroute LSALTs and a more direct route due to the higher drift down capability.

Or, FLI, maybe an accurate analysis of your operating environment, payload requirements, and acceptable risk exposure levels could be matched to a machine that IS capable of achieving your aims, rather than purchasing one that just doesnt do the job and trying to blame the manufacturers for insufficient power. They make machines with sufficient power for your mission profile, you just have to pay for it.

helmet fire,

I had similar thoughts in my unposted answer to FLI's posts, frankly I just gave up. Thanks!

FLI, the A++ is, IMO, far superior to the B model. The Arriel engines give lots of power, but are very efficient. We typically burn less than 600 lb/hr, unless someone gets in a big hurry. PT6s are reliable, but they are so fuel-hungry that they don't give you much range. With only a 10,800lb MGW, we can carry almost as much as a C+, and go a long way. We can't often carry a full 12 offshore hands, but 10 is common, going well over 100NM offshore. We couldn't fit the baggage for the other two, anyway. We often have to carry baggage in the cabin, strapped into the empty seats. I wouldn't want a B model, but the A++ is so much better than the straight A that it's like a different aircraft.

Engine manufacturers have come a long way, and are producing engines with more power and lower fuel consumption than were available a few decades ago, and airframe manufacturers are using them.

Helmet Fire said:

“The point was that the fuel dump is not effective on the rejected take off, nor after the TDP, but it is useful for the other 99.64% by giving you a much improved power margin for your subsequent actions.”

You brought up the issue of “brainspace” now read what I have been talking about in all of my post.

WE WANT TO REDUCE/ELIMINATE RTOD

The aircraft that I am familiar with that has fuel dump prohibits its use below 40Kts, regulations in the UK prohibit its use below 1000’, no gear operation during use and must be closed 1 minute before landing. As I said in a previous post, “If one is able to take off Cat A then, generally, one has Cat A enroute performance in most helicopter operations”. There will always be exceptions. “It would be useful to reduce weight for the OEI landing but the critical power phase is during T/O.” The fuel dump issue is a red herring to this discussion, period.

As previously stated, we are already flying in a 14 seater helicopter that has Cat A performance. Except, we only have 8 seats fitted! And still we find the performance marginal for onshore corporate/charter operations. What are you suggesting now…… a 22 seater for 6 pax? Again, as previously stated, the heavy helicopters are too big for most public use heli pads. We have already moved up one class in order to get some performance.

Nick, the points that I have been trying to get across are that the corporate customer, ‘he who actually pays for the machine’ has a perception, maybe carried from the fixed wing world, that a Cat A certification will ensure that if an engine should fail he and his family will be in no danger. My issue is that the performance on many machines with Cat A certification is so weak that we are not able to operate to full Cat A for most of the time. I am not talking about “Hard Core Cat A” at this time. Many times we have to operate to Cat A (Restricted). Most Corporate owners will not accept “limited exposure” as a concept, though that is what they have been exposed to, for a long time now, when operating to Cat A (R). I know that there are some operations that operate to Cat A all of the time but they have the luxury of site recce personnel, on site personnel and, normally, weeks of forward planning. For most operators this is not the case.
The UK Authority regulate for ‘full Cat A’ when operating in a congested area (a large proportion of England). The short field Cat A profiles for most helicopters still require a substantial reduction in payload and a RTOD. With temperatures regularly in the high 20’s during the summer, the penalty is even greater.

Now, I have no statistics to prove 2 engines are safer than one but I know that I couldn’t convince my customers that just 1 engine would be better! (It is a failing that most of us have if the number of twins is counted!) I haven’t been able to convince the CAA either! The manufacturers have not been convinced either or they would be promoting their medium singles a bit harder than they are!

Manufacturers, as suppliers to the industry, need to be aware of their customers needs. When asked, I will always say more power for my twin so that one day I can fly away OEI.
That day appears to be getting near, thankfully.

FLI,
you just dont get the risk management/risk exposure bits do you?
Or risk exposure V cost.
And I think you missed the brainspace bit too.
Oh and the bit about using fuel dump in an emergency. You know you are not permitted to crash either!

Repeat: if you want NO exposure you DO have 2 current options:

1. Reduce payload.
2. Buy a more powerful machine.

Do you really land at places in a heavy S76 that you could not squeeze a lightly loaded (reduced downwash) S61, S70, or maybe even B412 or AB139? Really? You land your corprate S76 in such tight areas that a few extra feet make all the difference?

I believe that if you have already moved up one class for your performace reasons then you have really not conducted a thorough analysis of requirements if you are already having problems. Or, if you customer changed their requirements - they must be aware of the extra cost.

Have you considered two light twins lightly loaded, ie 109s or EC135s?

Helmet Fire,

I don’t know why I am even replying to you!

If you read my post you will know that I certainly know what risk management/risk exposure/cost are all about.

What you appear to have no knowledge on is VIP Corporate/ Charter operations within UK, Europe and many other parts of the world. The types of customers and the regulations make life very difficult in this environment. Your cr*p about fuel dump for onshore VIP ops just highlights your complete lack of knowledge in this arena.

The type of clients that I am referring to do not buy old second hand aircraft!
They want new or nearly new. Up until now, there has been no aircraft that comprehensively covers all the conditions that I have been referring to. The Sikorsky 76B came close but was dis-continued.

Augusta has now produced an aircraft that will replace it. Watch how corporate clients trade in their 76’s, 155’s, 365's and 412’s to buy the AB139?

Then tell me there isn’t a market for a powerful twin!!

P.S. Not only do you know nothing about corporate aviation you don’t even know how to spell it! Same goes for performance! (See your previous post)

I hope that readers of this thread are finding it as informative as those of us who have been prepared to post.

Nick, in a previous email warned us to take care with the simple questions about Cat A or not Cat A; I might add my warning to his and use that as justification to clarify the usage of the term Category A. From a close reading of the definition(s) posted on the first page of this thread, it can be seen that the term is restricted to the landing and take-off phases - there is no such thing as en-route Cat A. FAR 29.67 - 'Climb: One Engine Inoperative (OEI)' is confined to establishing the requirement for first (at 200ft) and second (at 1000ft) segment climb requirements and, subsequent to revision 39, the production of data to establish the climb (or descent) data in the complete operating envelope. Whilst on the subject, there is also no such thing as Cat A Restricted (there is Group A - the UK performance standard, and Group A restricted - which was a less precise form of PC2).

It is therefore (quite rightly) left to operating regulations to stipulate what the en-route climb performance should be. In JAR-OPS 3 that requirement (simply stated) is for a 50ft/min climb performance at an altitude which gives obstacles clearance. Drift down is permitted as is fuel dump: The subtext for fuel dumping was discussed at great length before the words were chosen - in practice it is not as simple or as useful as it first appears; for offshore, if we refer to the previous discussion on one-way-fuel v beach-fuel - with one-way-fuel there is no possibility of use and with beach-fuel there is no need; there are specific onshore cases where fuel dump might be useful but when they exist, they need careful planning.

In FARs in the overwater case, the VFR requirement for en-route climb performance - 50ft /min at 1,000ft - is alleviated if floats are fitted FAR 135,183(d); and for the IFR case: onshore - requires 50ft/min at the MEA or 5,000ft, whichever is the higher; offshore - requires 50ft/min at the MEA or 1,500ft MSL, whichever is the higher.

Performance Classes give a much richer operational vocabulary particularly PC2 which describes exactly the points that Nick and others are making about a limited period when engine failure accountability is not provided on take-off and landing. The terms are written objectively and permit any number of methods of compliance.

Whether PC1 is used is a matter of policy for a number of interested parties: society will decide whether ‘exposure’ is permitted in a congested hostile environment (congested area) and customers (oil companies - and some cases like Norway - States) will decide whether zero exposure (PC1 or PC2e) is the standard for operations to helidecks. Provided that a large enough customer base exists for operations in PC1, the manufacturers will provide the equipment and the appropriate procedures. That these zero exposure options come at a cost is not in doubt; for some customers/States the prospect of not specifying zero exposure when it is possible (and it is) and then suffering a failure leading to death or injury is not a justifiable option.

If PC1 is not used (or is too costly in terms of loss of payload/range), PC2 provides the ability to establish the cost of exposure in a number of currencies. When the calculations are performed, the key elements will be the probability of failure, the consequence of failure and most important of all, whether the subsequent calculation is within the safety target chosen. The calculation for each aircraft type can be standard as the maximum exposure is, as Mars stated above, finite.

meow.

I hope I spelled it write.

Oh, and the AB139 - so you are going to buy a more powerful machine after all that?
Helmut.
:{

JimL: Here in Oz we have a slightly different enroute climb requirement OEI, and that is dependant upon category (airwork, charter, & VFR or IFR, etc) but it is essentially the same aim. You are right about the fuel dump not being so straight forward - it requires forethought and calculation prior to enroute use for the reasons you allude to: though I would contend that it is not rocket science. But at the take off and landing areas, it is very straight forward, simple to use, and of benefit. I also agree that it's use is of smaller benefit for offshore ops - but it is still of benefit. Overland, there are occaisions when our drift down requirement prevents me carrying preferred fuel loads in my current EMS job, let alone the take off and landing phases. And in the charter situation, it would greatly benefit our higher DA operations by allowing more fuel on take offs.

BTW, Does you fuel dump plan regulation actually say "the" heliport, or any heliport? In other words, is a diversion acceptable for fuel dumping purposes? Can "heliport" be met by a field, road or paddock, or does it mean a permanent helicopter landing site?

Helmet Fire,

The wording was specifically chosen so as not to constrain the operator; however, if use of fuel dump is planned (in the sense that it is known that an engine failure at some point will result in a lack of obstacle clearance) the resulting diversion must be know in order to ensure sufficient fuel reserves - this can include en-route alternates. The rules that have been quoted are, as with Australian regulations, aimed only at Commercial Air Transport (CAT). (T'was a time when fuel dump was used in the S61 to permit CAT B take-off from Aberdeen so that benefit could be taken for the overland portion; en-route climb performance had to be obtained before crossing the coast.)

You might have to accept that, for the purpose of this discussion (which is about take-off and landing performance), fuel dump has no real relevance.

None of what we are discussing is rocket science but there are a number of strongly held views that are somewhat related to the societal ethic of the State of Operation. For my own selfish motives, this thread does provide a platform to broadcast and discuss a number of concepts that we in Europe have been developing for a number of years.

Informed wisdom has it that the AB139 will only have one Category A procedure, a vertical profile with a (variable) TDP of 10ft or higher if an obstacle has to be cleared in the continued take-off; this will not require a Rejected Take-Off Distance (RTOD) larger than the pad (providing that visual cues can be maintained). One benefit will be the reduction of training (and training accidents) required for operations in PC1, and unconstrained PC1 offshore (until someone wishes to grow the aircraft).

Thanks JimL.
Could you touch on the last question I asked in relation to a heliport please?

Please keep at it with your "own selfish motives" so we can all continue to peer into the European intent of some of these rules and procedures. Thanks for the patience - it makes good reading.

Helmet Fire,

It was that question I was alluding to in the first paragraph of my response; yes you could have a fuel dump alternate which could be any landing area qualifying as a heliport.Note that this definition comes directly from Annex 6 Part III and should therefore be usable in any Contracting State - unless it is 'masked' by a local requirement. It has been adopted and used in JARs.

Thanks JimL,
We (in Australia) have not had much representation for the Annex 6 issues as yet, so thanks for the info.

I think the reason the fuel dump issue is becoming talked about at slightly crossed purposes is that the rules in Australia are different than Europe regarding max take off weight. I do not have the regulations to hand, but know from discussion with Australian colleagues, that because of the high temperatures routinely encountered it is not viable to operate to what we would consider normal PC1 or PC2 criteria. Allowable take off weight is more like a 0 rate of climb OEI weight or similar; is that right helmet? This may therefore be above the en-route weight.

Therefore, in that instance it may be of benefit to dump fuel on departure in the event of a failure. However, if operating to PC2 or PC1, the second segment climb requirement will be more limiting than the en-route weight restriction, unless there is a very restrictive MSA along the track, and so it is not normally of any benefit to have fuel dumping as an option.

The reference to the S-61 ops from Aberdeen is historical and relates to a regulatory regime long past that allowed Group B take off weights as long as fuel dump could ensure Group A en-route weight. This is a similar situation to the current Australian regulatory position, I think but stand to be corrected!

None of which is of any consolation to FLI and his passengers as they wrap themselves round a tree!

Helmet et al, don't be so quick to jump down others throats; generally if somone is quoting a sensible set of facts and concerns, they are probably grounded in some reality! I could go into some detail about client expectations in a new aircraft and how they relate to the actual delivered product, but it would be totally innapropriate in this context. However, the result highlights many of the concerns discussed above.

JimL,
My apologies for mixing up the various operating standards. I switched to Cat A instead of Group A so that a larger audience would understand what I was referring to.
Of course, Cat A (Restricted) should have been referred to as Group A (Restricted). Or PC2.
The reference to Cat A enroute was used, simplistically, to indicate sufficient single engine power to sustain level flight clear of all obstacles whilst flying to a landing site after segment 2 on the Group A T/O.
Thank you, for the very precise wording and explanations on PC1 and PC2.

Regarding fuel dump - you can't use it to reduce weight until after you've got Vtoss and the initial climb going. Check Part 29 and the Advisory Circular - it's a secondary control, and as such can't be used for performance purposes for determining all the necessary things until after you're safely climbing.
Also probably not a good idea to be trying to do it in what will be a pretty busy time anyway.

Even though this thread has slowed, it is not clear that we should be letting this subject go. Whilst there is a lull in proceedings and to allow time for all to draw a second breath here for your amusement and delectation are a couple of quotes. A bottle of champagne to the first guru who can tell us where they appeared and the year:

FAR 29.1, 31 January 1983.

Google is a very useful tool.

Well done GLSNightPilot! The document can be found at the following location

http://www.airweb.faa.gov/Regulatory...2568f600663576

The text that was quoted was indeed in the Final Rule text of Amdt. 29-21, Eff. 3/2/83.

Interestingly, NPRM 80-25 was issued on 12/15/80 and contained a proposal that would have required Category A for all helicopters certificated with 10 or more seats:In the event, the proposal to meet an operational requirement of PC1 for helicopters with 10 or more seats was not carried and, with one exception, the applicability of FAR 29.1 was downgraded to a requirement to meet PC2. The exception; helicopters with Maximum Gross Weight greater than 20,000 pounds and certificated with more than 9 passenger seats, for which the requirement remained… hang on! Doesn’t the S92 fit into that category? In Europe, FAR 29.1 appears to be seen only as a certification requirement.

The results of the FAA deliberations can be seen in a modified form in the JAR-OPS applicability for the Performance Classes:

How wide of the mark was the original aspiration contained in the referenced text:well, considering that statement was probably drafted between 1980 and 1982, it is difficult to estimate what time scale ultimately was meant to encompass (did they consider that we would still be discussing this 24 years later?). Isn’t it interesting though that, for a number of good reasons, the FAR 27 twins have arrived at that destination already but, as they are limited to 9 passenger seats, were never intended even to make the journey.

My contention would be that we have also arrived for the FAR 29 helicopters that were designed after the application of this NPRM; that this cannot be done for all sites, under all operating conditions and at the maximum mass, is a feature of the flexibility of the helicopter not one of lack of intent or engineering skills. It is therefore for operational regulations to establish the conditions under which any necessary gap might be bridged. Risk Assessment provides the tools to establish what that gap might be under a particular circumstance, and whether to use PC2 (with exposure) to bridge that gap - or reduce payload and operate in PC1. For offshore operations, we now have the added tool of performance modelling to virtually reduce that performance gap to nil - operating in accordance with PC2e but without compromising the pilot’s discretion.

Every day it is possible to make the last minute tweaks - the introduction of the CT7-8A will add another 5% to the available performance with the same geometry and without modification to the airframe; how, by clever engineering and by using different materials to improve the 30 second rating by about 140hp. This appears to be something for nothing as the 30 second rating should never be used and does not have any operational cost.

Nick opened this thread describing the dilemma:It has been the belief of a number of us for some considerable time that performance, as with all aviation matters, is not an ‘either or’ choice. What we should be debating is the management of safety - which is not measured in absolute terms but expressed as safety targets.

That two views are expressed already indicates that any manufacturer who wishes to maximise its market, has to position its product so that it can meet both aspirations. The one that cannot be satisfied is that which demands PC1 for all sizes of sites at all density altitudes.

Recent developments have increased the number of risk management tools; performance modelling has shown that, for offshore operations, the margin of exposure (due to performance) can be reduced to a theoretical zero. Why the conditional statement? Because those of us who have been in offshore operations for a number of years will know that, on occasions, the environmental conditions and the obstacle environment, prevents us from flying the optimum profile.

For the uninitiated, there are three (theoretical) subdivisions of PC2 that an operator can take advantage of; these range from nil exposure (without using Category A procedures) to limited exposure - and are as follows (not in that order):

Nick has indicated that, on PPrune, he does not speak for his company but as an individual; that this is correct can be observed by the actions of Sikorsky which appears to be doing precisely what is described above and is positioning the S92 to meet the performance aspirations of its actual and potential customers (whatever camp they might be in).

What we have to hope for (because we have no information on which to base any assumptions) is that Eurocopter will take note of the enlightened attitude of Sikorsky, and also position their products (the EC225, EC155 and AS332L2) to meet both sets of aspirations.

JimL,

I am a bit confused with your explanaition on the performance on the S92.

This is an article that I found on the H-92 written last year at the Paris Air show.
I quote just part of the article.

“The civil S-92 aircraft on which the H-92 Superhawk is based has already achieved U.S. certification. Standard S-92 safety features that will be found in the H-92 Superhawk include flaw tolerant components, multiple redundant control systems, bird strike protection, high-intensity radiated field protection and category A (class 1) performance, which allows pilots to continue safe flight in the event of an engine failure at any point in flight”.

Full article can be found here:
http://www.ainonline.com/Publication...d2h92pg14.html

The article implies that the S92 will have, so called, “Hard Core”/ ”Full Cat A”. Is this correct? Are there substantial payload reductions or DA restrictions to achieve this?

JimL,

Thanks for clarifying the case with your last post. Note that the performance for Cat A is not a sharp decision, yes or no, as you say. I believe few helicopters will come out where the maximum weight allows full Cat A, because the ability to recoup this extra power as payload for other operations will be so compelling that the aircraft will have two or three operating procedures, one for hard Cat A, and one for lesser OEI but a higher MGW and much better payload/range. Thus one design will serve several possible customer bases.

This debate has unfortunately not driven into the kind of discussion I had hoped, because it became a vote on hard Cat A yes or no, and not a discussion of safer or less safe.

It seems that so many vocal regulators and some customers (FLI out there?) speak as though the solution to helicopter operational safety concerns is more power. This is in spite of the data, and of the real hazards. If the debate does not move off this as a flip switch, yes/no, helicopter safety will suffer for another generation, I believe.

I am struck too at the inability of we who make the machines to express the cost to a design to meet these requirements - the plots I provided that showed a massive penalty for hard Cat A were virtually ignored by all, as if they were not part of the discussion, perhaps because I phrased the discussion so poorly.

So, here is a possibly new way to state the question:

Given that a helicopter will be designed to lose 25% of its range (or the equivilent payload) and this penalty assigned to safety concerns, what concerns should be addressed? A possible sample:

Hover to hover full Instrument procedures to heliports in rural and urban areas, independant of airplane operations

Pilot visionics, where the pilot sees the world through a see-through virtual reality device, with FLIR and CGI mixed so that night/instrument is as if he were in a simulator, and VFR like rules are applied to all traffic.

Hard terrain avoidance, where the machine is not capable of being driven into the ground except as a controlled landing. This includes brown out and zero light available circumstances.

Maintenance free operation for a full year, during which only pilot pre-flight inspection is required, and during which all maintenance activities are diagnosed by the aircraft

Tolerance to accept common corrosion, damage and mishandling so that no unsafe condition is developed for the year.

Ability to Fly in any icing, rain, or wind condition without loss of control.

Fly with the noise signature of a common large car, so that ground observers note no objectionable noise, even in rural areas.

As a helicopter R&D engineer, I can state that all the above are not just possible, they can be certified within 10 years. And none will cost half of what hard Cat A does cost to the design. As someone who wishes the best for all of us (we are one big family in a way) I simply cannot understand why we are not asking for these things to be legislated!


And for FLI, your questions about the Cat A performance of the S-92 have already been answered in this thread. It is my belief that the S-92 is the most capable hard Cat A platform now available, with more payload, range, speed from a hard Cat A operation off a rig or from ground level than any helicopter. However, this thread has nothing to do with any specific helo, in spite of your wish to make my general comments somehow specific to any given helicopter's capabilities. You might just be one of those fellows who just never gets the message, sadly.

Well said Nick - for the third or fourth time this thread.

Is it that the operators are really not savvy enough to buy a machine that is capable of flexibility - or is it that the customer really hates to think (or cannot understand) that there is an empty seat next to them in order to reduce their risk exposure? Or can they in no way be educated about this?

I note that FLI said they had adjusted the seating of the aircraft to 6 in order to achieve greater power margin, so why not look at your operating envelope, pick the max DA and range your customer will make you operate to - couple it with the exposure profile they desire - then fit the max number of seats that will be able to be filled? Hey presto: you have achieved what you want: a "hardcore Cat A" machine without penalising other buyers who can accept different risk exposure.

Or maybe the answer to "the customer is always right" thing when education fails, is to give them what they want. How about Sikorsky produce a VIP S76 with only four seats in the back so that it can be considered to have the best PC1 rating known to man, and then a utility version for those who want to adapt to flexible performance/exposure/cost profiles depandant upon missions?

Nick: lets not divert spending into areas that can resolve higher risks to helicopter operations, lets produce machines that never require performance planning.:ok:

Regulations for Cat A capabilities are in place. The regulatory bodies feel that it IS a safety concern. (Third party liability.....can't have helicopters landing on people in the street below when the aircraft misses the rooftop helipad OEI.)

The problem as I see it is that companies may be ignoring the fact. Hesitant to bring their customers up to date on the Cat A issue for fear of lost contracts or closed flight departments. Regulatory bodies do not enforce the regulations that they have put in place until, as Nick says, once in 55 years, we have an accident.

Whether we feel that money could be better spent elsewhere is a great topic for discussion. This topic really should have been discussed between operators, manufacturers and regulatory bodies before the regulations were put into effect. Now the guy caught in the middle is the pilot. Surprise surprise.

For the record Nick, I think we could spend our money more wisely than having full Cat A capability but the regulatory body in this country doesn't seem to agree.

Cheers