Category A Takeoff: Background
AnFI,
Without more info on the numbers, you don't have a case.
Can you from your numbers above, perhaps tell us the number of flight hours generated for twins and for singles, so we can divide the dead per hour? You can keep it for the UK for now, and we get the numbers world wide later.
Maybe you can give us a list of controlled in flight engine shut-downs (twin), due to some sort of problems, where the result was return to base, land and do some extra paperwork vs. Single engine failure, forced landing/crash and even more paperwork done by someone else?! Also per flight hours? The UK would do for now.
Preferably, split into private/corporate non AOC work vs. commercial operation.
Without more info on the numbers, you don't have a case.
Can you from your numbers above, perhaps tell us the number of flight hours generated for twins and for singles, so we can divide the dead per hour? You can keep it for the UK for now, and we get the numbers world wide later.
Maybe you can give us a list of controlled in flight engine shut-downs (twin), due to some sort of problems, where the result was return to base, land and do some extra paperwork vs. Single engine failure, forced landing/crash and even more paperwork done by someone else?! Also per flight hours? The UK would do for now.
Preferably, split into private/corporate non AOC work vs. commercial operation.
Without background data such as the amount of missions or hours flown, or even the number of accidents avoided, numbers on their own are meaningless.
The heavier category aircraft have all had a larger crew count, thus more fatalities, which has been used to imply the aircraft are less safe, which is creative mathematics in action.
Including Clutha in the calculation is just plain old fashioned scumminess.
With the backwards logic demonstrated, you would have to conclude that airline travel is incredibly unsafe - just look at the fatalities each year.
In Anfi's world that probably makes sense since those poor buggars are stuck with up to 4 engines, that's more than double the danger of any twin.
It should be measured in terms of ALoSP (agree?), the people considering this issue are not producing this figure.
Why not? because it doesn't work?
Why not? because it doesn't work?
Imagine if someone, say, ran out of fuel and lost an aircraft (fortunately without loss of life) and then was untruthful about the cause of the fuel shortage (piss poor planning perhaps) - surely that person would be guilty of undermining the whole ASoLP process - just a hypothetical scenario but worthy of consideration.
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DB
COST BENEFIT ANALYSIS: CBA
Yes - what you say is the B part, I agree!!! Not in dispute (mostly)
To make a valid decision you need to look at the C part: The COST
You cant just claim the B without the C. Can you? Do you not accept that there IS a cost?
Many are 'uninteded consequences', that cannot justly be ignored.
The Costs are many, some:
Economic activity stifled, jobs lost, utility hampered, ordinary people (taxpayers) priced out of utility of helicopters, super wealthy 'elites' only? Tried hiring/buying your own helicopter?
Fuel pressure: to be tight on fuel because you carry engine redundancy may not be safest.
Complexity of airframe, applies to systems and pilots, causes accidents that would not otherwise occur:
Leicester: as crab says a helicopter of AW139 size (due to engine redundancy) HAS to have a hydraulic Tail Rotor. It killed them.
Cultha: SIX (?) working fuel pumps and an experienced pilot can't get the 20+mins fuel remaining to the engines, because the system is complex and the pilot is confused, perhaps, because it is a twin prompting feeder tanks. 'Captain Murphy' will always come through.
AS332/H225: Gearbox's madly complex, breaks killing several helicopters full of people - FORTUNATELY not over urban areas, otherwise that COST would be very ovious.
Bigger energy impacts - imagine 15tons of helicopter in the Albert Hall on Proms night.
You cannot shut down the wrong engine in a single.
Critical components work harder: Any twin would have better margins for the same payload for many critical systems, (eg TR authority, etc etc etc).
Complexity has consequences !!!
If you don't asses the COST part of CBA, then you are clearly distorting the arguement.
I'd love to hear from JimL on this. ANY rationale? CBA? What's your 'A' part?
To exactly quote JimL:
"The argument that simplicity is safer than complexity is a given, only the consequence is in question"
I agree, DB - you don't?
What is the quantification of risk to 3rd parties on the ground ? ALoSP??? What is it?
We need to know because we must weigh the C against the B that you correctly identify.
We have to DO the 'A'. ABC : CBA !!
(ref 4 engines, yes ETOPS calculations include reduced risk of negative consequences of more engines (that can explode, and CAUSE the problem), this is similar to the exposure to more freewheel units, for example, EH101, Thruxton AS355)
[Crab - no argument with the Authorities, the Authorities have no view on this topic.
There are former employees, 'consulting', with a view to impose this on the rest of the world through ICAO.
They'll have consulting jobs for life, trying to explain to developing counties why they must take off upwards and backwards.
They are trying to move the goal posts: Hostile Areas WILL lead to Catastropic outcomes - really???
The current ICAO "land without undue hazard to persons and property on the ground" is being changed completely to become a Catastrophy requiring 10^-9. T'aint right, wake up world these rules are coming your way soon !!
They have not given their rationale.
They will undermine the credibility of the ICAO base line (and others), that has done so much good for the world.]
Bell, yes the stats are open to abuse, but one should try, feel free, go ahead, try and find neutral truth. Maybe twins do 4 times as many pax.hours, I don't know, i doubt it, but even then it doesn't seem like a good result does it? Worth the COSTs?
COST BENEFIT ANALYSIS: CBA
Yes - what you say is the B part, I agree!!! Not in dispute (mostly)
To make a valid decision you need to look at the C part: The COST
You cant just claim the B without the C. Can you? Do you not accept that there IS a cost?
Many are 'uninteded consequences', that cannot justly be ignored.
The Costs are many, some:
Economic activity stifled, jobs lost, utility hampered, ordinary people (taxpayers) priced out of utility of helicopters, super wealthy 'elites' only? Tried hiring/buying your own helicopter?
Fuel pressure: to be tight on fuel because you carry engine redundancy may not be safest.
Complexity of airframe, applies to systems and pilots, causes accidents that would not otherwise occur:
Leicester: as crab says a helicopter of AW139 size (due to engine redundancy) HAS to have a hydraulic Tail Rotor. It killed them.
Cultha: SIX (?) working fuel pumps and an experienced pilot can't get the 20+mins fuel remaining to the engines, because the system is complex and the pilot is confused, perhaps, because it is a twin prompting feeder tanks. 'Captain Murphy' will always come through.
AS332/H225: Gearbox's madly complex, breaks killing several helicopters full of people - FORTUNATELY not over urban areas, otherwise that COST would be very ovious.
Bigger energy impacts - imagine 15tons of helicopter in the Albert Hall on Proms night.
You cannot shut down the wrong engine in a single.
Critical components work harder: Any twin would have better margins for the same payload for many critical systems, (eg TR authority, etc etc etc).
Complexity has consequences !!!
If you don't asses the COST part of CBA, then you are clearly distorting the arguement.
I'd love to hear from JimL on this. ANY rationale? CBA? What's your 'A' part?
To exactly quote JimL:
"The argument that simplicity is safer than complexity is a given, only the consequence is in question"
I agree, DB - you don't?
What is the quantification of risk to 3rd parties on the ground ? ALoSP??? What is it?
We need to know because we must weigh the C against the B that you correctly identify.
We have to DO the 'A'. ABC : CBA !!
(ref 4 engines, yes ETOPS calculations include reduced risk of negative consequences of more engines (that can explode, and CAUSE the problem), this is similar to the exposure to more freewheel units, for example, EH101, Thruxton AS355)
[Crab - no argument with the Authorities, the Authorities have no view on this topic.
There are former employees, 'consulting', with a view to impose this on the rest of the world through ICAO.
They'll have consulting jobs for life, trying to explain to developing counties why they must take off upwards and backwards.
They are trying to move the goal posts: Hostile Areas WILL lead to Catastropic outcomes - really???
The current ICAO "land without undue hazard to persons and property on the ground" is being changed completely to become a Catastrophy requiring 10^-9. T'aint right, wake up world these rules are coming your way soon !!
They have not given their rationale.
They will undermine the credibility of the ICAO base line (and others), that has done so much good for the world.]
Bell, yes the stats are open to abuse, but one should try, feel free, go ahead, try and find neutral truth. Maybe twins do 4 times as many pax.hours, I don't know, i doubt it, but even then it doesn't seem like a good result does it? Worth the COSTs?
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ANFI, assuming you drive a car on a public road Iassume you have it insured. You pay this every year. Everyone does and yet very very few have accidents that involve claiming on the Insurance.
‘The second engine provides the same insurance against an unlikely event. You don’t then say because I have not had an engine failure I can do without it forever.
Having said that, and this you may not know, in certain operations we exploit the reliability of both engines, to operate AEO where an OEI event could be catastrophic. We call it PC2 With Exposure. To do it we have to prove reliability, monitor the engines with HUMs and crucially, operate the helicopter in accordance with procedures to minimise the exposure time.
Such operations are restricted to those that exist in the public interest like HEMS or HOFO.
The same rule applies to SEHs but no one has ever exploited it. You can but wonder why.
DB
‘The second engine provides the same insurance against an unlikely event. You don’t then say because I have not had an engine failure I can do without it forever.
Having said that, and this you may not know, in certain operations we exploit the reliability of both engines, to operate AEO where an OEI event could be catastrophic. We call it PC2 With Exposure. To do it we have to prove reliability, monitor the engines with HUMs and crucially, operate the helicopter in accordance with procedures to minimise the exposure time.
Such operations are restricted to those that exist in the public interest like HEMS or HOFO.
The same rule applies to SEHs but no one has ever exploited it. You can but wonder why.
DB
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A fully "Mandraulic" helicopter i.e. one without powered flight controls cannot, by definition, have an autopilot. Any helicopter flown in IMC requires an autopilot. Having trained to fly unstabilised, single engined helicopters in IMC from an early stage in my career and having had to fly an unstabilised twin in a later public transport role (it used to be allowed some twenty years ago), I would not want to do it ever again.
One engine = one power source for electrical equipment. If it stops, you are going downhill and possibly without some of the normal electrical systems, making your life even more difficult.
Accident statistics involving twin engined helicopters operating over congested areas might seem relatively high compared to singles, but a single cannot have an accident over a congested area if it is not allowed to be flown there.
One engine = one power source for electrical equipment. If it stops, you are going downhill and possibly without some of the normal electrical systems, making your life even more difficult.
Accident statistics involving twin engined helicopters operating over congested areas might seem relatively high compared to singles, but a single cannot have an accident over a congested area if it is not allowed to be flown there.
class is closed for today
All things aside, the regulator decides what can and can't be done with a single or twin, flight over water being a biggy.
Remember the early days of a certain twin, we became expert at single engine landings (not that it takes any great skill) because of precautionary shutdowns. Engines were eventually sorted. Not unlike the MAX having recent engine failure troubles, down to carbon build up on the combustor disrupting airflow pattern. Glad it had another to get back, else there would be a third MAX in the dirt, parked in the suburbs of Orlando.
Last edited by megan; 23rd Apr 2019 at 01:10.
AnFI, I've tried to stay out of the circular arguments that ensue from your assertions, but I'd suggest that statistical analysis is one area that you need to brush up. Flat base stats without background are meaningless, since the exposure of single/multi engine types to the operational areas is a main feature which is ignored by you yet would significantly change the data that you are (so far) presenting.
Something like the year-to-date road fatalities so loved by many roads and policing authorities which completely ignore VKT, annual growth numbers, age groupings, 5 year trends, 12 month comparisons etc. You really are making a bit of a clot of yourself by creating inaccurate data references which mean absolutely nothing
You can choose to ignore that regulators determine the minimum required for operations and that this has been done as a result of many hard lessons learned over decades.
There is only so much you can move with a single, to be cost-effective, how much and how fast you can transport something is of more importance to the cost equation.
Add to that the liability should something go wrong, and what another engine costs becomes unimportant.
Why do you think Boeing and Airbus aren't investing their money in single-engined airliners?
You continue to choose ridiculously over-simplified points to support an argument that is entirely non-sensical.
If you really want to save everyone some money, then perhaps you can also discuss how pointless certification and testing is. This really does cost people money, so let's get rid of that also, it's just unnecessary regulation if you ask me.
While you're at it, all this training that has to be done. What a waste of time and money, let's get rid of that as well.
We need more visionaries like you
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DB, Shy, megan, JE and BR
There are some really good points there, thank you.
They do throw out a few elements out that might help the religious extremists understand the infidels, and maybe vice versa.
DB: 2 engines as an insurance policy. Very good point on so many levels. If you had no accidents in many years then you would expect the premium to be low. ie STILL WORTH PAYING. If the premium is ridiculously expensive then it fails
Cost Benefit Analysis.
So its all about CBA !
Fully comp, 3rd Party?? $10k per year to insure the hull of a $10k automobile, not worth it. So 3rd party only.
INSURANCE (premium) IS A MEASURE of the RISK.
3rd Party Insurance for a helicopter to insure the risk of people on the ground IS THE free market PRICING of this risk.
Look at the ground payout risk to insurance companies for Twin Engine helicopters in urban areas. Cultha is expensive.
North Sea helicopters over cities... could be very expensive.
Carrying a spare engine as an insurance policy is very expensive:
What cost 500kg being carried for 100,000hrs??? $100,000,000?? Very expensive just to insure against a 'fender bender'. Unrealistic.
It does not indicate it's worth it, and because it doesn't make sense the state(? or who ?) imposes it. T'aint right.
People are generally upset with being pushed around without justification. We expect more from our 'experts'.
["applies to SEHs but no one has ever exploited it." (I think an operator out of London Heliport does)]
Hi Shy, my engineering degree friend, some questions for you:
1 'Mandraulics' (great term) sure, agree - no good for autopilots.
As for Tail Rotors: IF Hyd TR is not necessary AND HydTR can kill you, THEN do you chose HydTR? (AW139 drivers?)
2 "One engine = one power source for electrical equipment." Sounds like a thoroughly lousy reason to carry a spare engine.
Spare electricity can be provided in so many more ways. Maybe like HYD, a GENi on the XMsn(?), if you were really worried about that then 30kg of extra batteries would do it ... OR 500kg of spare engine complication ((that can kill you)).
Which source of spare electricity would you chose?
3 'Stats against Twins look bad, because the singles aren't flying there'. You said it. YES THEY DO LOOK BAD... they are bad. The singles ARE THERE (eg only restricted in LONDON by R160) and the rest of history and the rest of the world leaves a data set that blows that argument away, and that argument flips the other way too: look at the MAJOR twin accidents that have not killed people on the ground because they were over barren sea/land, and NOT over urban areas !! Had they been over urban areas we'd have a total disaster for helicopters in general. (maybe over the NS but over London? A risk worth taking??)
4 Engineering wise: isn't simplicity the goal? Leonardo DaVinci, Simplicity is the ultimate sophistication. Occam, Newton, Einstein, KISS (Kelly Johnson). Not a fan of simplicity ?
megan "the regulator decides what can and can't be done", yes and has a duty to do so judiciously (for better reasons than just the retirement plans of some ex-employees). They have a LEGAL DUTY to decide in a judicious way.
They have not laid out their reasoning, and they should. Is it ok to avoid the daylight and push this through on the QT? What is their ALoSP? What is the likely fatality rate in 3rd Party Deaths per 100,000 hours of urban overflight? How does it compare to singles? Estimates anyone?
"Remember the early days of a certain twin, we became expert at single engine landings" I think the common theme often here is the "early days", and it makes the position understandable. Sure in the very 'early days' there were 2 engines because they didn't have single engines powerful enough. Engines were very unreliable, and there's no doubt that there's a reliability number at which it is worth carrying a spare. There's also a number at which it is not worth it. THAT number is the question. For instance at 1 per million hours, the price of carrying a spare is almost certainly not worth the Cost of carriage, Complexity (pilot and systems) and Increased failures of other systems compared to the very very rare usefulness of it, will not be 'worth it'.
JE
You are right, there's no analysis from me there, it's just a fact but it's not an inacurate one (as you alledge). There are all kinds of factors to apply to see it 'in context'.(ie make excuses for it). It's not good though is it? There'd have to be a lot of flying going on in twins to reverse that bad news for twins. 8 times more to make twins just twice as good. If twins, with all their other mitigators, only managed twice as good would it be worth it? Twins are flown by more experienced pilots, required to have more training, often are Multi Pilot (the biggest yeilding factor), more likely to have better other equipment.
According to EASA Safety Review 2018
25% of Offshore fatal accidents were from engine failure (twin)
5% of Other Comercial Air Transport was engine failure (also twin, no singles), most other causes were wires and weather and LOC.
However we want to spin the stats (and they are spinable, of course), there is just not a clear case, especially if you want to be rational or proportionate, or to actually cost the idea. I note your criticism of police authorities wrt road fatalities.
BR "Now, I am no expert in aircraft economics but it does occur to me that what determines if a type is profitable or cost-effective to run, requires a few more variables than just the number of engines, and the associated capital and direct operational costs." Well I think that is a really good point. The scale IS important. When the aircraft is LARGE, and carries many people there is a good case for carriage of a spare engine. It becomes a very small proportion of payload and expense. So the CBA may well show a favourable result for larger helicopters.
"many hard lessons learned over decades." yes, mostly decades ago !! Out of date now.
I understand a lot of 'old timers' are emotionally attached to spare engines. Don't want to re-evaluate their religion.
"to be cost-effective, how much and how fast you can transport something is of more importance to the cost equation."
Good point, so there's a size element to the estimation, I agree.
"the liability should something go wrong, and what another engine costs becomes unimportant." This is imagined fear, and the cost is not unimportant, it needs to be proportionate, It does cost more than money, some big accidents too... GREDL over LONDON!?!? Cultha? They need to be factored in also.
Smaller helicopters make smaller holes in the ground and don't economically/justifiably carry a spare engine so well.
"Boeing and Airbus aren't investing their money in single-engined airliners?" It really is different for Airliners. Airliners carry many more people, land with much greater destructive energy (more than just a fender-bender), do have 'independant engines', don't have a common output mechanism, don't have so many other critical components that could use the performance expenditure better, aren't so critical on pure capabilities. From the 'Airline world' Pilatus really proves the point that smaller scale singles do outperform twins. Commanche anyone? If a single makes sense in an aeroplane it makes more sense in a helicopter.
"ridiculously over-simplified points" well it's either too complex or too simple, no pleasing some people. KISS !! ?
(and THEN you have to ask: If you put the same amount of effort it making a simplex system not fail, as the resource you put in to 'preserve its unreliability' through redundancy then what result would you get?
You'd get a helicopter that didn't need redundancy, along with all it's downside costs.)
Come on America, you want to have to use twins?
There are some really good points there, thank you.
They do throw out a few elements out that might help the religious extremists understand the infidels, and maybe vice versa.
DB: 2 engines as an insurance policy. Very good point on so many levels. If you had no accidents in many years then you would expect the premium to be low. ie STILL WORTH PAYING. If the premium is ridiculously expensive then it fails
Cost Benefit Analysis.
So its all about CBA !
Fully comp, 3rd Party?? $10k per year to insure the hull of a $10k automobile, not worth it. So 3rd party only.
INSURANCE (premium) IS A MEASURE of the RISK.
3rd Party Insurance for a helicopter to insure the risk of people on the ground IS THE free market PRICING of this risk.
Look at the ground payout risk to insurance companies for Twin Engine helicopters in urban areas. Cultha is expensive.
North Sea helicopters over cities... could be very expensive.
Carrying a spare engine as an insurance policy is very expensive:
What cost 500kg being carried for 100,000hrs??? $100,000,000?? Very expensive just to insure against a 'fender bender'. Unrealistic.
It does not indicate it's worth it, and because it doesn't make sense the state(? or who ?) imposes it. T'aint right.
People are generally upset with being pushed around without justification. We expect more from our 'experts'.
["applies to SEHs but no one has ever exploited it." (I think an operator out of London Heliport does)]
Hi Shy, my engineering degree friend, some questions for you:
1 'Mandraulics' (great term) sure, agree - no good for autopilots.
As for Tail Rotors: IF Hyd TR is not necessary AND HydTR can kill you, THEN do you chose HydTR? (AW139 drivers?)
2 "One engine = one power source for electrical equipment." Sounds like a thoroughly lousy reason to carry a spare engine.
Spare electricity can be provided in so many more ways. Maybe like HYD, a GENi on the XMsn(?), if you were really worried about that then 30kg of extra batteries would do it ... OR 500kg of spare engine complication ((that can kill you)).
Which source of spare electricity would you chose?
3 'Stats against Twins look bad, because the singles aren't flying there'. You said it. YES THEY DO LOOK BAD... they are bad. The singles ARE THERE (eg only restricted in LONDON by R160) and the rest of history and the rest of the world leaves a data set that blows that argument away, and that argument flips the other way too: look at the MAJOR twin accidents that have not killed people on the ground because they were over barren sea/land, and NOT over urban areas !! Had they been over urban areas we'd have a total disaster for helicopters in general. (maybe over the NS but over London? A risk worth taking??)
4 Engineering wise: isn't simplicity the goal? Leonardo DaVinci, Simplicity is the ultimate sophistication. Occam, Newton, Einstein, KISS (Kelly Johnson). Not a fan of simplicity ?
megan "the regulator decides what can and can't be done", yes and has a duty to do so judiciously (for better reasons than just the retirement plans of some ex-employees). They have a LEGAL DUTY to decide in a judicious way.
They have not laid out their reasoning, and they should. Is it ok to avoid the daylight and push this through on the QT? What is their ALoSP? What is the likely fatality rate in 3rd Party Deaths per 100,000 hours of urban overflight? How does it compare to singles? Estimates anyone?
"Remember the early days of a certain twin, we became expert at single engine landings" I think the common theme often here is the "early days", and it makes the position understandable. Sure in the very 'early days' there were 2 engines because they didn't have single engines powerful enough. Engines were very unreliable, and there's no doubt that there's a reliability number at which it is worth carrying a spare. There's also a number at which it is not worth it. THAT number is the question. For instance at 1 per million hours, the price of carrying a spare is almost certainly not worth the Cost of carriage, Complexity (pilot and systems) and Increased failures of other systems compared to the very very rare usefulness of it, will not be 'worth it'.
JE
You are right, there's no analysis from me there, it's just a fact but it's not an inacurate one (as you alledge). There are all kinds of factors to apply to see it 'in context'.(ie make excuses for it). It's not good though is it? There'd have to be a lot of flying going on in twins to reverse that bad news for twins. 8 times more to make twins just twice as good. If twins, with all their other mitigators, only managed twice as good would it be worth it? Twins are flown by more experienced pilots, required to have more training, often are Multi Pilot (the biggest yeilding factor), more likely to have better other equipment.
According to EASA Safety Review 2018
25% of Offshore fatal accidents were from engine failure (twin)
5% of Other Comercial Air Transport was engine failure (also twin, no singles), most other causes were wires and weather and LOC.
However we want to spin the stats (and they are spinable, of course), there is just not a clear case, especially if you want to be rational or proportionate, or to actually cost the idea. I note your criticism of police authorities wrt road fatalities.
BR "Now, I am no expert in aircraft economics but it does occur to me that what determines if a type is profitable or cost-effective to run, requires a few more variables than just the number of engines, and the associated capital and direct operational costs." Well I think that is a really good point. The scale IS important. When the aircraft is LARGE, and carries many people there is a good case for carriage of a spare engine. It becomes a very small proportion of payload and expense. So the CBA may well show a favourable result for larger helicopters.
"many hard lessons learned over decades." yes, mostly decades ago !! Out of date now.
I understand a lot of 'old timers' are emotionally attached to spare engines. Don't want to re-evaluate their religion.
"to be cost-effective, how much and how fast you can transport something is of more importance to the cost equation."
Good point, so there's a size element to the estimation, I agree.
"the liability should something go wrong, and what another engine costs becomes unimportant." This is imagined fear, and the cost is not unimportant, it needs to be proportionate, It does cost more than money, some big accidents too... GREDL over LONDON!?!? Cultha? They need to be factored in also.
Smaller helicopters make smaller holes in the ground and don't economically/justifiably carry a spare engine so well.
"Boeing and Airbus aren't investing their money in single-engined airliners?" It really is different for Airliners. Airliners carry many more people, land with much greater destructive energy (more than just a fender-bender), do have 'independant engines', don't have a common output mechanism, don't have so many other critical components that could use the performance expenditure better, aren't so critical on pure capabilities. From the 'Airline world' Pilatus really proves the point that smaller scale singles do outperform twins. Commanche anyone? If a single makes sense in an aeroplane it makes more sense in a helicopter.
"ridiculously over-simplified points" well it's either too complex or too simple, no pleasing some people. KISS !! ?
(and THEN you have to ask: If you put the same amount of effort it making a simplex system not fail, as the resource you put in to 'preserve its unreliability' through redundancy then what result would you get?
You'd get a helicopter that didn't need redundancy, along with all it's downside costs.)
Come on America, you want to have to use twins?
Last edited by AnFI; 25th Apr 2019 at 00:18. Reason: sp
Breaking News - The AnFI Aviation Safety Authority has discovered that all accidents were preceded by the crew eating food. The recommendation is that henceforth all crews be not permitted to eat food.
look at the MAJOR twin accidents that have not killed people on the ground because they were over barren sea/land, and NOT over urban areas !! Had they been over urban areas we'd have a total disaster for helicopters in general.
'Look, over there, that's really bad - imagine if it was over here!' So very Daily Mail and no basis for anything other than scaremongering.
IF Hyd TR is not necessary AND HydTR can kill you, THEN do you chose HydTR? (AW139 drivers?)
Even light singles trying to get by on a non-hyd TR can run out of authority because the designer is trying to keep the disc loading low.
And btw the crash you keep harping back to was a 169 not a 139 - another erroneous 'fact' from you.
Any TR can fail and kill you, especially in a 400' hover at high power - your argument, as usual, lacks logical progression - just because it was a hyd TR doesn't mean all other TRs are inherently safe.
Do you seriously want free access to London for singles? What is wrong with the existing helilanes? They allow sufficient access whilst minimising risk to those below - what is wrong with that.
Twins can be allowed more freedom but are still most likely to be routed along the helilanes so what is your beef - do you want all singles to have the same freedoms as the air ambulance, police and SAR? That wouldn't make doing their job more difficult would it????
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Hi Shy, my engineering degree friend, some questions for you:
1 'Mandraulics' (great term) sure, agree - no good for autopilots.
As for Tail Rotors: IF Hyd TR is not necessary AND HydTR can kill you, THEN do you chose HydTR? (AW139 drivers?)
2 "One engine = one power source for electrical equipment." Sounds like a thoroughly lousy reason to carry a spare engine.
Spare electricity can be provided in so many more ways. Maybe like HYD, a GENi on the XMsn(?), if you were really worried about that then 30kg of extra batteries would do it ... OR 500kg of spare engine complication ((that can kill you)).
Which source of spare electricity would you chose?
3 'Stats against Twins look bad, because the singles aren't flying there'. You said it. YES THEY DO LOOK BAD... they are bad. The singles ARE THERE (eg only restricted in LONDON by R160) and the rest of history and the rest of the world leaves a data set that blows that argument away, and that argument flips the other way too: look at the MAJOR twin accidents that have not killed people on the ground because they were over barren sea/land, and NOT over urban areas !! Had they been over urban areas we'd have a total disaster for helicopters in general. (maybe over the NS but over London? A risk worth taking??)
4 Engineering wise: isn't simplicity the goal? Leonardo DaVinci, Simplicity is the ultimate sophistication. Occam, Newton, Einstein, KISS (Kelly Johnson). Not a fan of simplicity ?
1 'Mandraulics' (great term) sure, agree - no good for autopilots.
As for Tail Rotors: IF Hyd TR is not necessary AND HydTR can kill you, THEN do you chose HydTR? (AW139 drivers?)
2 "One engine = one power source for electrical equipment." Sounds like a thoroughly lousy reason to carry a spare engine.
Spare electricity can be provided in so many more ways. Maybe like HYD, a GENi on the XMsn(?), if you were really worried about that then 30kg of extra batteries would do it ... OR 500kg of spare engine complication ((that can kill you)).
Which source of spare electricity would you chose?
3 'Stats against Twins look bad, because the singles aren't flying there'. You said it. YES THEY DO LOOK BAD... they are bad. The singles ARE THERE (eg only restricted in LONDON by R160) and the rest of history and the rest of the world leaves a data set that blows that argument away, and that argument flips the other way too: look at the MAJOR twin accidents that have not killed people on the ground because they were over barren sea/land, and NOT over urban areas !! Had they been over urban areas we'd have a total disaster for helicopters in general. (maybe over the NS but over London? A risk worth taking??)
4 Engineering wise: isn't simplicity the goal? Leonardo DaVinci, Simplicity is the ultimate sophistication. Occam, Newton, Einstein, KISS (Kelly Johnson). Not a fan of simplicity ?
2) The main thrust (!) of your campaign is to make the main rotor gearbox simpler by only having one engine. Yet now you advocate making them more complicated to generate electrical power.... I fail to see any contiguous logic in that.
3) I take it that you operate singles in other congested areas. I hope that you make a point of obtaining the necessary CAA Permissions. I always do, for twin engined helicopters.
4) Engineering always requires compromises and there is seldom a simple answer. There could never be an autopilot or stability systems, a point I already stated and with which you agreed. Pilot fatigue would become a more important factor. If you wanted to build a large helicopter with no hydraulics, there would be considerable design compromises. These would include heavier control runs, which in turn would require structural reinforcement, adding weight and reducing payload. A much larger, single engine, rather than two smaller ones, would require a far stronger and heavier gearbox that you might at first imagine. Again, it would require a far heavier structure to support it. A doubling of size doesn't necessarily result in a doubling of material strength. - it might require a "square" increase. Again, see my answer 2).
A further point. I noticed that you posted your last two replies at 01:07 and 03:54. As flattered as I am that you consider me a friend and that a prompt reply to my post obviously so important for you to stay up so late, I suggest you get more sleep, it helps engender rational thought. Obviously, as an instructor, you already will know that. I'm not flying today, but still got a good night's sleep. I hope you aren't in the air until well rested.
Last edited by ShyTorque; 25th Apr 2019 at 11:43.
The main thrust (!) of your campaign is to make the main rotor gearbox simpler by only driving one engine
Cost - of allowing SEH unrestricted access over congested/hostile areas = negligible, just a paperwork exercise
Benefit - to those few exercising such privileges = increased freedom - to those millions living underneath the privileged few = decreased through noise and additional risk as any failure is likely to lead to loss of life on the ground.
Analysis - pretty much a waste of time since - to quote Mr Spock - the needs of the many outweigh the needs (or desires in this case) of the few
Benefit - to those few exercising such privileges = increased freedom - to those millions living underneath the privileged few = decreased through noise and additional risk as any failure is likely to lead to loss of life on the ground.
Analysis - pretty much a waste of time since - to quote Mr Spock - the needs of the many outweigh the needs (or desires in this case) of the few
Avoid imitations
Join Date: Nov 2000
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Incredibly, they do seem to get this right without flattening people below.
Catastrophic failures do seem to be few and far between.
Statistics for the US FY 2018 – first % is fleet size, second % is accidents. To make it easy those in blue have zero accidents
S350 7% 5%
BK117 2% 3%
EC120 1%
EC130 2% 3%
EC135 2%
SA330J < 1% 1%
206Bs 8% 6%
206Ls 5% 1%
212 1%
407 6% 3%
412 1%
429 1%
R-22 7% 15%
R-44 13% 21%
R-66 2% 1%
S-76 2% 3%
S-92 1%
Brantly B-2 1% 1%
Enstrom 280 1% 1%
480 1%
F28 1%
Cabri G2 < 1% 1%
Hiller UH-12/H-23 2%
Leonardo A109 1% 1%
(formerly Agusta Westland) A119 1%
AW139 1%
MDHI369 6% 15%
600N < 1% 1%
Restricted Category (all TCs) HH-1/TH-1/UH-1 5% 5%
OH-58 3% 4%
Schweizer Rotorcraft Services Group 269/300/TH-55 4% 8%
Scott's Bell 47 5% 1%
S350 7% 5%
BK117 2% 3%
EC120 1%
EC130 2% 3%
EC135 2%
SA330J < 1% 1%
206Bs 8% 6%
206Ls 5% 1%
212 1%
407 6% 3%
412 1%
429 1%
R-22 7% 15%
R-44 13% 21%
R-66 2% 1%
S-76 2% 3%
S-92 1%
Brantly B-2 1% 1%
Enstrom 280 1% 1%
480 1%
F28 1%
Cabri G2 < 1% 1%
Hiller UH-12/H-23 2%
Leonardo A109 1% 1%
(formerly Agusta Westland) A119 1%
AW139 1%
MDHI369 6% 15%
600N < 1% 1%
Restricted Category (all TCs) HH-1/TH-1/UH-1 5% 5%
OH-58 3% 4%
Schweizer Rotorcraft Services Group 269/300/TH-55 4% 8%
Scott's Bell 47 5% 1%
Megan - don't tell AnFI but it almost looks like single engine helicopters have the highest accident rate......................surely that can't be true or AnFI would have told the truth in the first place