Fly By Wire
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Just because NH-90 does not have a civil certification does not mean FBW cannot be certified under civil regulations. There are the options to modify the control laws of the FBW/AFCS/PFCS that are just not possible with conventional mechanical control systems. Depending on flight regime the results of the same control input has different outcomes, which can enhance the handling qualities of a helicopter severely! Up to now I have not met a single pilot who does not like the handling qualities of NH-90!
Who wants to invade North Korea? To me the dark side of the moon is more interesting to invade than this little ****ehole run by that Fatf**k with the funny haircut. But I have to admitt, it is interesting to see how a discussion on FBW drifts off to the invasion of Korea!
Who wants to invade North Korea? To me the dark side of the moon is more interesting to invade than this little ****ehole run by that Fatf**k with the funny haircut. But I have to admitt, it is interesting to see how a discussion on FBW drifts off to the invasion of Korea!
Certainly not implying your "an elephant is a mammal, therefore all mammals are elephants" point! I just wonder whether its worth the hassle for a conventional helicopter.
I'm sure the NH90 is nice to fly, that is not in dispute, although I have to say that the cockpit HMI seems quite clunky and old fashioned (yes, I've had a go, but only in the Simulator), but the of course the origins of its designs are last century.
There is already some difficulty with pilots dealing with advanced automation - the "Whats it doing now?" call is still heard. At least we can teach that instead of saying that, you drop down one or more levels of automation ultimately until you are hand flying. If you want to say "Whats it doing now" whilst FBW "hand flying", what do you do then?
FBW didn't help the Air France bods.
N Korea - just to make the point about the EMP since that is probably the most likely source of an EMP at the moment!
I'm sure the NH90 is nice to fly, that is not in dispute, although I have to say that the cockpit HMI seems quite clunky and old fashioned (yes, I've had a go, but only in the Simulator), but the of course the origins of its designs are last century.
There is already some difficulty with pilots dealing with advanced automation - the "Whats it doing now?" call is still heard. At least we can teach that instead of saying that, you drop down one or more levels of automation ultimately until you are hand flying. If you want to say "Whats it doing now" whilst FBW "hand flying", what do you do then?
FBW didn't help the Air France bods.
N Korea - just to make the point about the EMP since that is probably the most likely source of an EMP at the moment!
Last edited by HeliComparator; 23rd Apr 2013 at 09:28.
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Incidentally the heli I fly already has 7 sources of electrical power, two alternators / TRUs driven by the main gearbox, a hydraulically driven turbine generator for emergency backup, a small alternator on each engine for FADEC supply, a main battery and a standby battery.
In terms of relative safety, does anyone know what kind of processors are used to translate the electrical impulses into mechanical movements at the actuator level. What kind of vulnerability do these imply over the existing methods of control? I assume these are circuit boards which then activate servos? What kind of shielding/protection/redundancy do these have?
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Well, I understand your concernes in regard to EMP, but without any experience made in that field all we can do is to speculate.
The AF447 Flight did not have any probs with FBW, as far as I know. The root case were wrong indications due to failing external sensors and apparently the crew failed in the interpretation of cockpit displays. I believe the result would have been exactly the same if that airbus would have had conventional mechanical controls and a conventional AFCS.
The biggest difference in FBW in Planks and Helicopters is that in Planks the FBW will not let you exceed defined limits, while in the helicopters there is no limitation or restriction programmed into the FBW. It is a common misbelieve that NH-90 will limit the pilots inputs when coming close to potentialy dangerous attitudes or flightconditions. In that regard it is like a mechanical control system, it will just feed the pilots input into the rotors, no matter whether that will result in the exceedance of limits or not.
With your remarks on the MMI you are spot on! A nicely sized cockpit, but but the architecture of the MFDs and especially the DKU hold a lot of room for improvements, but then none of the glass cockpits I have flown in the last 10 years (quite a lot) were anywhere close to perfect.
The AF447 Flight did not have any probs with FBW, as far as I know. The root case were wrong indications due to failing external sensors and apparently the crew failed in the interpretation of cockpit displays. I believe the result would have been exactly the same if that airbus would have had conventional mechanical controls and a conventional AFCS.
The biggest difference in FBW in Planks and Helicopters is that in Planks the FBW will not let you exceed defined limits, while in the helicopters there is no limitation or restriction programmed into the FBW. It is a common misbelieve that NH-90 will limit the pilots inputs when coming close to potentialy dangerous attitudes or flightconditions. In that regard it is like a mechanical control system, it will just feed the pilots input into the rotors, no matter whether that will result in the exceedance of limits or not.
With your remarks on the MMI you are spot on! A nicely sized cockpit, but but the architecture of the MFDs and especially the DKU hold a lot of room for improvements, but then none of the glass cockpits I have flown in the last 10 years (quite a lot) were anywhere close to perfect.
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From a comment on Flight Global -
Combat Helicopters and Fly-By-Wire - Defence - Defence - Aviation Forums - Flightglobal Airspace
There are times when I think Fly-By-Wire (FBW) enthusiasm is getting out of hand. Some reasons for my concerns:
About 1982 a prototype SH60B Seahawk was performing an automatic approach to hover over the deck of a frigate when the ship turned on its radar. The Automatic Flight Control System (AFCS) went badly wrong, forcing the pilot to shut the system down and take manual control to save the aircraft.
Also in the 1980s a Black Hawk helicopter flying by a 50,000 watt commercial radio tower crashed when the movable horizontal stabilator (the only FBW control on the aircraft, was driven to the full down position forcing the helicopter into an uncontrolled dive. The crew died.
After both these incidents the aircraft systems were successfully hardened to prevent the reoccurrence of the incident. Now for the a present example of concern;
In an military technology magazine in the 1990s was an article on future energy weapons in which was described an incident where an AGISS cruiser locked onto a passing F-16 with a focused beam from its SPY-1 radar (a Phased Array type radar). The F-16 lost control to such an extent, that the pilot declared an emergency and only regained control when the radar operator turned off the radar. The article goes on to note the Navy was continuing studies into the affect of the focused radar beam on FBW systems.
Putting these examples together with the ban on using cell phones and other electronic equipment by passengers in commercial airliners one has to come to the conclusion that outside electronic interference and FBW may not mix very well.
I have worked in the helicopter industry for the past few decades, and I have begun to be concerned about this push to FBW in combat helicopters. It seems to me to be a Let’s-Get-On-The-Bandwagon philosophy, driven by generals and engineers with very little thought about the ramifications on the pilot and crew who will fly in harms way.
Basically flying a helicopter is vintage World War One flying, low altitude and low speed, with no parachute. Besides that helicopters have proven extremely bad at gliding. They autorotate down, this requires a definite control input, which would be lacking in a fried FBW system. Current combat helicopters have redundant control runs and multiple load path linkages, mechanical systems, which are augmented by AFCS to ease pilot work load and the controls have mostly benign failure modes. The benign modes are because a hundred years of aviation trial and error have made mechanical flight controls (MFC) harder to damage and to fail catastrophically (though, of course, it can happen).
Now there are good points to FBW, such control improvements reduce pilot work loads, however modern AFCS do the same. As observed by comparison of the UH60L with the new UH60M, the “M” is much easier to fly than the “L”. The “M” AFCS is 21st century, as compared to the 1980s technology of the “L”, with loads of workload reducing options. Come to think of it, the AFCS computer on board the UH60M is based on FBW without the wire control runs. If this is so with the US Army’s newest combat aircraft, what then is the performance improvement that justifies the costs and risks of adding a FBW system to a helicopter, especially when the result of FBW failure is death.
If the AFCS (the computer gets fried) goes down on the UH60M, the pilot can still fly manually. If he had to, he could even complete his mission. The engines though installed with electronic fuel control still have a redundant mechanical backup. All this designed in redundancy is based on the combat short comings of the Huey in Vietnam.
What I am afraid of is there will come a time when anyone with a powerfull radar and ultimately a designed for purpose energy weapon will start disabling or destroying FBW systems and especially with Helicopters there will be no recovery and no bail out, because the new whizz-bang technology won out to common sense.
About 1982 a prototype SH60B Seahawk was performing an automatic approach to hover over the deck of a frigate when the ship turned on its radar. The Automatic Flight Control System (AFCS) went badly wrong, forcing the pilot to shut the system down and take manual control to save the aircraft.
Also in the 1980s a Black Hawk helicopter flying by a 50,000 watt commercial radio tower crashed when the movable horizontal stabilator (the only FBW control on the aircraft, was driven to the full down position forcing the helicopter into an uncontrolled dive. The crew died.
After both these incidents the aircraft systems were successfully hardened to prevent the reoccurrence of the incident. Now for the a present example of concern;
In an military technology magazine in the 1990s was an article on future energy weapons in which was described an incident where an AGISS cruiser locked onto a passing F-16 with a focused beam from its SPY-1 radar (a Phased Array type radar). The F-16 lost control to such an extent, that the pilot declared an emergency and only regained control when the radar operator turned off the radar. The article goes on to note the Navy was continuing studies into the affect of the focused radar beam on FBW systems.
Putting these examples together with the ban on using cell phones and other electronic equipment by passengers in commercial airliners one has to come to the conclusion that outside electronic interference and FBW may not mix very well.
I have worked in the helicopter industry for the past few decades, and I have begun to be concerned about this push to FBW in combat helicopters. It seems to me to be a Let’s-Get-On-The-Bandwagon philosophy, driven by generals and engineers with very little thought about the ramifications on the pilot and crew who will fly in harms way.
Basically flying a helicopter is vintage World War One flying, low altitude and low speed, with no parachute. Besides that helicopters have proven extremely bad at gliding. They autorotate down, this requires a definite control input, which would be lacking in a fried FBW system. Current combat helicopters have redundant control runs and multiple load path linkages, mechanical systems, which are augmented by AFCS to ease pilot work load and the controls have mostly benign failure modes. The benign modes are because a hundred years of aviation trial and error have made mechanical flight controls (MFC) harder to damage and to fail catastrophically (though, of course, it can happen).
Now there are good points to FBW, such control improvements reduce pilot work loads, however modern AFCS do the same. As observed by comparison of the UH60L with the new UH60M, the “M” is much easier to fly than the “L”. The “M” AFCS is 21st century, as compared to the 1980s technology of the “L”, with loads of workload reducing options. Come to think of it, the AFCS computer on board the UH60M is based on FBW without the wire control runs. If this is so with the US Army’s newest combat aircraft, what then is the performance improvement that justifies the costs and risks of adding a FBW system to a helicopter, especially when the result of FBW failure is death.
If the AFCS (the computer gets fried) goes down on the UH60M, the pilot can still fly manually. If he had to, he could even complete his mission. The engines though installed with electronic fuel control still have a redundant mechanical backup. All this designed in redundancy is based on the combat short comings of the Huey in Vietnam.
What I am afraid of is there will come a time when anyone with a powerfull radar and ultimately a designed for purpose energy weapon will start disabling or destroying FBW systems and especially with Helicopters there will be no recovery and no bail out, because the new whizz-bang technology won out to common sense.
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In the case of AF447 perhaps the outcome would have been different if the aircraft had a conventional control wheel (yoke) instead of the side stick.
According to the findings, during almost the entire time the aircraft was falling, the F/O (who had the controls as PF) kept pulling the sidestick all the way back, thus never giving the aircraft a chance to get out of the stall.
Should the aircraft had a conventional control column, there is a possibility that the PNF would have noticed this wrong reaction and intervened to correct it in time, thus avoiding the crash.
Of course this will only remain a speculation and never be proven.
According to the findings, during almost the entire time the aircraft was falling, the F/O (who had the controls as PF) kept pulling the sidestick all the way back, thus never giving the aircraft a chance to get out of the stall.
Should the aircraft had a conventional control column, there is a possibility that the PNF would have noticed this wrong reaction and intervened to correct it in time, thus avoiding the crash.
Of course this will only remain a speculation and never be proven.
HtH the point about FBW was made to show the hazards of over-complicated basic controls. In normal mode, pulling the side stick right back wouldn't stall the aircraft, but with the air data discrepancies the software had gone into fallback mode where the flight envelope protection was inoperative. I guess the pilots didn't know or realise this. As SS says, the fact that one pilot couldn't see what the other was doing to the primary flight controls was probably contributory.
As I said at the beginning, I am not against technological advancement, but it should be incorporated with a clear sense of the benefits and down-sides, (with the latter outweighing the former) not just because it looks all shiny in a glossy brochure.
Glass cockpits: the NH90 felt clunky compared to the 225, though to be fair the latter obviously has much less kit to interface with. Never mind, could be worse, could be like an S92!
As I said at the beginning, I am not against technological advancement, but it should be incorporated with a clear sense of the benefits and down-sides, (with the latter outweighing the former) not just because it looks all shiny in a glossy brochure.
Glass cockpits: the NH90 felt clunky compared to the 225, though to be fair the latter obviously has much less kit to interface with. Never mind, could be worse, could be like an S92!
Last edited by HeliComparator; 23rd Apr 2013 at 10:39.
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HC, and I in turn support your view when you said:
Can I ask - in the 225, these 7 power sources, are they automatically managed to provide power as and where needed in the event that one or more electrical generating source goes offline?
As I said at the beginning, I am not against technological advancement, but it should be incorporated with a clear sense of the benefits and down-sides, (with the latter outweighing the former) not just because it looks all shiny in a glossy brochure.
225 power
HS, its rather complicated,
2 alternators /TRUs are the normal source of generated power. If one fails, the other can supply all reasonable needs automatically.
If both fail, some non-essential services are automatically shed. The pilot has to select the hydraulic generator manually and some further services are shed but for example its still happy to do a hands-off ILS with auto-level-off at the bottom.
If that fails as well, you are automatically down to the main battery which obviously has limited life. If that fails you are automatically down to the emergency battery. You lose a lot of stuff at that point but at least retain the standby horizon, airspeed, altitude display. Electrical power for the FADECs / Engine governing would be assured by the small alternators on the engines.
These engine alternators normally power the FADECs after start, but if they fail the system automatically reverts to airframe power - any of the power sources above except the standby battery. But these engine FADEC alternators are small and can't be used to power anything else on the airframe.
So although there are 7 power sources, they can't all be used to power everything since the smaller ones have their power limits. However I mentioned it to show that helis already have multiple power sources, so the concept is there even if the detail would have to change for FBW.
2 alternators /TRUs are the normal source of generated power. If one fails, the other can supply all reasonable needs automatically.
If both fail, some non-essential services are automatically shed. The pilot has to select the hydraulic generator manually and some further services are shed but for example its still happy to do a hands-off ILS with auto-level-off at the bottom.
If that fails as well, you are automatically down to the main battery which obviously has limited life. If that fails you are automatically down to the emergency battery. You lose a lot of stuff at that point but at least retain the standby horizon, airspeed, altitude display. Electrical power for the FADECs / Engine governing would be assured by the small alternators on the engines.
These engine alternators normally power the FADECs after start, but if they fail the system automatically reverts to airframe power - any of the power sources above except the standby battery. But these engine FADEC alternators are small and can't be used to power anything else on the airframe.
So although there are 7 power sources, they can't all be used to power everything since the smaller ones have their power limits. However I mentioned it to show that helis already have multiple power sources, so the concept is there even if the detail would have to change for FBW.
Last edited by HeliComparator; 23rd Apr 2013 at 11:20.
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There was a Qantas A330 that performed a violent uncommanded maneuver that was attributed to a dodgy nav box that was supplying the FBW system with the next level of efficiencies of automation. As I understand it the nav box sent the flight director a bunch of corrupt messages which then told the autopilot to act like a roller coaster.
The bus's side sticks didn't move during the violent maneuver, had it been a helicopter it would probably have broken itself apart.
I don't want to bag FBW, there is good and bad engineering everywhere, and fortunately the engineering of FBW is maturing quite rapidly with a corresponding price tag to match.
Aren't those little flaperons on Kaman helicopter's main rotor blades electrically controlled, is it a FBW system?
The bus's side sticks didn't move during the violent maneuver, had it been a helicopter it would probably have broken itself apart.
I don't want to bag FBW, there is good and bad engineering everywhere, and fortunately the engineering of FBW is maturing quite rapidly with a corresponding price tag to match.
Aren't those little flaperons on Kaman helicopter's main rotor blades electrically controlled, is it a FBW system?
Flight Global Info
HS,
Re the UH-60 anecdote reported in the Flight Global article: unfortunately typical of the apocrypha that went around for a few years in fact regarding the stabilator. There was only one stabilator induced crash, and that was the 1978 crash of one of the prototypes at Sikorsky. That had nothing to do with EMI or the like, but was incomplete maintenance done during an all-nighter to get the ship ready for a VIP ride in the morning, coupled with an inexplicable failure by the crew to utilize the dual, backup straight to the actuators DC manual controls. There was however, an event that took place in Korea in the 80's, wherein a 60A was flying by a Hawk Missile Battery, who thought they would practice on it using their radar, with the result being that the Stabilator electronics reverted from the auto mode to the manual mode.
The Seahawk story is news to me, but after reading the 60A inaccuracies, am skeptical. And skeptical not only because they had the 60A story completely wrong, but also because, being involved in the Seahawk first flight thru development, I am aware of the scope of the EMI invasive testing the USN put the machine thru at PXT. Given the mission of the machine, it was exposed to all of the naval electronic transmission equipment, from the carrier radars on down.
" never say never in aviation " the saying goes, but I would guess the real story about this Seahawk event might be different.
One other observation for HC and the EC community re redundant power sources etc.: it always surprised us at SA that EC never upgraded to installing an APU as standard equipment in the Super Puma line. It really does provide benefits across the board, not only for dispersed field operations and ease of maintenance, but well, take the blade de-icing system. If the ship has one main generator go down, the Hawk or 92 pilot can fire up the APU and continue. Not an end of the world difference, but sure nice to have the all around capability. In the Hawk, up to a pretty decent altitude/ temperature combo, the pilot can hit BOTH engine start buttons simultaneously and start both engines at the same time ( APU bleed air used for start ).
Re the UH-60 anecdote reported in the Flight Global article: unfortunately typical of the apocrypha that went around for a few years in fact regarding the stabilator. There was only one stabilator induced crash, and that was the 1978 crash of one of the prototypes at Sikorsky. That had nothing to do with EMI or the like, but was incomplete maintenance done during an all-nighter to get the ship ready for a VIP ride in the morning, coupled with an inexplicable failure by the crew to utilize the dual, backup straight to the actuators DC manual controls. There was however, an event that took place in Korea in the 80's, wherein a 60A was flying by a Hawk Missile Battery, who thought they would practice on it using their radar, with the result being that the Stabilator electronics reverted from the auto mode to the manual mode.
The Seahawk story is news to me, but after reading the 60A inaccuracies, am skeptical. And skeptical not only because they had the 60A story completely wrong, but also because, being involved in the Seahawk first flight thru development, I am aware of the scope of the EMI invasive testing the USN put the machine thru at PXT. Given the mission of the machine, it was exposed to all of the naval electronic transmission equipment, from the carrier radars on down.
" never say never in aviation " the saying goes, but I would guess the real story about this Seahawk event might be different.
One other observation for HC and the EC community re redundant power sources etc.: it always surprised us at SA that EC never upgraded to installing an APU as standard equipment in the Super Puma line. It really does provide benefits across the board, not only for dispersed field operations and ease of maintenance, but well, take the blade de-icing system. If the ship has one main generator go down, the Hawk or 92 pilot can fire up the APU and continue. Not an end of the world difference, but sure nice to have the all around capability. In the Hawk, up to a pretty decent altitude/ temperature combo, the pilot can hit BOTH engine start buttons simultaneously and start both engines at the same time ( APU bleed air used for start ).
Last edited by JohnDixson; 23rd Apr 2013 at 12:16. Reason: Typo and additional phrasing
Not having flown a heli with an APU maybe I am biased, but in the examples you give the blade deicing on a 225 continues to work on one alternator (they are big alternators) and you can press both start buttons at the same time, although I grant you that starting will then take place consecuitively not concurrently due to the limitations of the DC supply system. Airstart means the APU must be working, otherwise your bird is dead - ie a single point failure. A few plusses and minuses there but when you include the additional weight and maintenance of what is effectively a third engine, I'm not sure the case for APU is clear cut. Of course if you want to run your aircon before startup, APU is great and that's why EC offer it as an option for VIP / hot weather (not usually a problem in Aberdeen!)
Follow-Up
HC, on Hawks and 92 one can start one engine from bleed air sourced at the other, operating engine ( there is a switch labelled " Crossbleed "). On Hawks, there is also an external air source fitting, thus one can either, start using any standard external air cart, or, yes, connect one Hawk to another for a " buddy-start ", using a long air hose ( one or two per lift company ). Vietnam era pilots will readily understand the Army's focus on not repeating the oft-used expedient of trundling a ni-cad from one Huey to another to get the CA on the road.
PM on the way re ambients.
PM on the way re ambients.
Last edited by JohnDixson; 23rd Apr 2013 at 15:45. Reason: Addition
