Wires - strikes, cutters and detectors
Helicopter Pilots Get It Up Quicker
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WLM... I asked if these were being considered but Tim T's (?) answer was no because of the increased weight to the airframe would make it unfeasible.
PW
PW
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Wire Strike Protection Systems are actually quite a complicated design problem.
The quoted 90% protection is not a reliable number. The frontal area protected varies depending on type and design, and can be much lower, perhaps as low as 60% if the design is not good. Some of the variables have to do with the dynamics of a wire strike well forward of the cutters, cruise attitude, rotor disk depth in flight, and various protuberances on the forward structure of helos. There are also issues with primary structure not working well with the wire cutters. The wire cutters depend on the forward structure passing the wires into the cutter, while in many types there is a tendency for the wire to dig in at some discontinuity or weak point in the structure.
Nevertheless, well designed WSPSs do provide substantial protection, typically for not a great deal of weight burden. The cost is driven by the analysis and testing required to validate the scheme for the particular type.
The various wire detection systems have the advantage that avoidance rather than accommodation can eliminate serious incidents. On the other hand, they are active systems with failure modes. The real reason why they are not making further inroads is that they all, at this stage, involve significant weight penalty in the range of 30-60 lb., and are quite expensive.
I'm told that Goodrich have a goal of bringing their avoidance system cost down to a level where the authorities could mandate use for medium/large helo installations.
That would be a good result, as wire strike risks reduce the effectiveness of a helo vs. fixed wing. At low level, it is often very difficult to see wires. I believe that some type of protection is very desirable for most helo operations.
The quoted 90% protection is not a reliable number. The frontal area protected varies depending on type and design, and can be much lower, perhaps as low as 60% if the design is not good. Some of the variables have to do with the dynamics of a wire strike well forward of the cutters, cruise attitude, rotor disk depth in flight, and various protuberances on the forward structure of helos. There are also issues with primary structure not working well with the wire cutters. The wire cutters depend on the forward structure passing the wires into the cutter, while in many types there is a tendency for the wire to dig in at some discontinuity or weak point in the structure.
Nevertheless, well designed WSPSs do provide substantial protection, typically for not a great deal of weight burden. The cost is driven by the analysis and testing required to validate the scheme for the particular type.
The various wire detection systems have the advantage that avoidance rather than accommodation can eliminate serious incidents. On the other hand, they are active systems with failure modes. The real reason why they are not making further inroads is that they all, at this stage, involve significant weight penalty in the range of 30-60 lb., and are quite expensive.
I'm told that Goodrich have a goal of bringing their avoidance system cost down to a level where the authorities could mandate use for medium/large helo installations.
That would be a good result, as wire strike risks reduce the effectiveness of a helo vs. fixed wing. At low level, it is often very difficult to see wires. I believe that some type of protection is very desirable for most helo operations.
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To WLM
WLM, After flying in Indonesia dodging 1999 of those 2000 kites in the air i faxed RHC about WSPS. Reply basically said fittment of cutters was unfeasible due to not only the weight of the cutters but the structual changes reqd to the airframe to fit the cutters. I assume fitment of cutters ate to much into the payload of the machine. Shame as they may have come in handy cutting the 200mts of 50lb fishing line that wrapped itself around the pitch links and swash plate after not seeing that 2000th kite.
Cheers
Cheers
Iconoclast
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A tale of dead turkeys and two severed telephone lines.
I was flight mechanic on a Bell HTL-1 (early model 47) and we were returning to base in Traverse City, Michigan. We had a leaky tail rotor gearbox so every fifty miles or so we would land and I would fill up the gearbox with of all things, fish oil. Very smelly stuff. My pilot, who had been involved in several crashes, was easily freaked out.
While flying in the left seat I was holding the oil can between my legs and reading a map. We were about twenty minutes out when the pilot saw a bear. He very excitedly told me to look. When I leaned over, my legs spread and the can hit the deck making a loud bang. The pilot thought there was something wrong with the tail rotor gearbox and he made a quick turn looking for a spot to land. In the process of making his maneuver he really made a hard over. On that particular helicopter type when there was an excessive side load on the mast it would cause the planetary gears to really growl.
Upon hearing that, he really wanted to get on the ground. He picked out a landing spot in front of what we later found out was a veterinarians office. To get from where we were to that landing spot we had to pass over a turkey farm and in the process we made the turkeys stampede and over 100 birds were killed in the pileup at the fence surrounding the turkey farm.
Oh yes, in the process of landing, we took out the vets' telephone line.
In another instance also in an HTL-1 we were landing between the tower and the main hangar at Dover Air Force Base in Dover, Delaware and in the process we took out the telephone line between the two buiildings.
While flying in the left seat I was holding the oil can between my legs and reading a map. We were about twenty minutes out when the pilot saw a bear. He very excitedly told me to look. When I leaned over, my legs spread and the can hit the deck making a loud bang. The pilot thought there was something wrong with the tail rotor gearbox and he made a quick turn looking for a spot to land. In the process of making his maneuver he really made a hard over. On that particular helicopter type when there was an excessive side load on the mast it would cause the planetary gears to really growl.
Upon hearing that, he really wanted to get on the ground. He picked out a landing spot in front of what we later found out was a veterinarians office. To get from where we were to that landing spot we had to pass over a turkey farm and in the process we made the turkeys stampede and over 100 birds were killed in the pileup at the fence surrounding the turkey farm.
Oh yes, in the process of landing, we took out the vets' telephone line.
In another instance also in an HTL-1 we were landing between the tower and the main hangar at Dover Air Force Base in Dover, Delaware and in the process we took out the telephone line between the two buiildings.
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PW thank you for the reply
EVOD You never told me about this mate....There I am zooming along looking for suitable fishing places you know where.....
Better increase my insurance cover I think
Cheers
WLM
EVOD You never told me about this mate....There I am zooming along looking for suitable fishing places you know where.....
Better increase my insurance cover I think
Cheers
WLM
Senis Semper Fidelis
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Wire cutters will only work up to a certain diametre of wire, and will require a considerably forward motion to act as a cutter,
In any metal cutting be it Steel or non ferous material whatever cutter is used the actual cutter never cuts more than 20 to 30 %
of the thickness or the diametre of the object being cut, that is because of a physical attribute that in the metal trade is referred to as " Shear Break".
Steel as used in guy ropes is normally multi cored wound wire, and will carry a tensile strength of between 28 to 42 tonnes, copper is about half of that , but supprisingly Alu can be much higher due to design, so that it caters for such things as distance being strung out and velocity of wind, these are designed to cater for the once in a hundred years massive gale that would beat all others, so if you were to hit such cables at low speed the chance of a clean cut would be sadly not good, alternativly if you hit at high speed the strength of the cable would very simply rip the cutter from the heli body.
best to avoid at all costs!
Vfr
In any metal cutting be it Steel or non ferous material whatever cutter is used the actual cutter never cuts more than 20 to 30 %
of the thickness or the diametre of the object being cut, that is because of a physical attribute that in the metal trade is referred to as " Shear Break".
Steel as used in guy ropes is normally multi cored wound wire, and will carry a tensile strength of between 28 to 42 tonnes, copper is about half of that , but supprisingly Alu can be much higher due to design, so that it caters for such things as distance being strung out and velocity of wind, these are designed to cater for the once in a hundred years massive gale that would beat all others, so if you were to hit such cables at low speed the chance of a clean cut would be sadly not good, alternativly if you hit at high speed the strength of the cable would very simply rip the cutter from the heli body.
best to avoid at all costs!
Vfr
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Three colleagues of mine were very fortunate a few years ago when they hit a set of domestic power lines. They were flying up a valley on a low level nav trip (military support helos) and were heading NE, approaching a village that was on the eastern side of the valley as the valley bent NW. A set of domestic wires were marked on the map heading West away from the village and they spotted a set of telegraph poles in the base of the valley orientated E-W.
They turned NW to follow the valley at about 150' and biased themselves away from the village to avoid it. They then saw a set of wires immediately in front of the aircraft and simultaneously pulled back on the cyclic and up on the collective. (As you would!!)
The wires went under the aircraft and at least one got caught around the tailwheel. It must have snapped some way away from the aircraft and been pulled across it, because there was scoring on the tailwheel yoke and a nice big witness mark around the tailboom! They landed in a field immediately in front of them and had to be recovered later by a downbird team.
Very lucky boys and a very sobering sight for anyone who later saw the airframe! Local village weren't too impressed with the inadvertent power cut either!
They turned NW to follow the valley at about 150' and biased themselves away from the village to avoid it. They then saw a set of wires immediately in front of the aircraft and simultaneously pulled back on the cyclic and up on the collective. (As you would!!)
The wires went under the aircraft and at least one got caught around the tailwheel. It must have snapped some way away from the aircraft and been pulled across it, because there was scoring on the tailwheel yoke and a nice big witness mark around the tailboom! They landed in a field immediately in front of them and had to be recovered later by a downbird team.
Very lucky boys and a very sobering sight for anyone who later saw the airframe! Local village weren't too impressed with the inadvertent power cut either!
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Blackhawk Wire Strike FNQ
Just heard an Army Blackhawk has collected some wires near Mission Beach Far North Queensland - any more info?
Last edited by Max Dover; 26th Sep 2004 at 04:01.
Not enough $$$ ...
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Lifted from D&G:
Sydney Morning Herald
September 26, 2004 - 12:21PM
The crew of an army Black Hawk helicopter escaped injury today after it clipped power lines and made an emergency landing in far north Queensland.
The accident happened during a joint military exercise, about 10km from El Arish, south of Innisfail.
A helicopter ambulance and several road ambulances were rushed to the scene but their services were not needed, a Queensland Ambulance Service Spokesman said.
A defence spokesman said the pilot of the helicopter had been able to make an emergency landing after it struck the power lines while taking part in operation Swift Eagle.
The military exercise had commandoes practising advance force operations such as seizing and holding a sea port.
The spokesman said it was not known yet how many people were on board the helicopter.
"The helicopter got down safely and no one was injured," the spokesman said.
He said an investigation had already begun into the cause of the incident.
Earlier this year six army personnel were injured when a Black Hawk clipped a tree during an exercise near Oakey, west of Toowoomba and crashed.
Australia's worst Black Hawk accident occurred in June 1996 when 18 people died after two of the helicopters collided during a night exercise in north Queensland.
AAP
September 26, 2004 - 12:21PM
The crew of an army Black Hawk helicopter escaped injury today after it clipped power lines and made an emergency landing in far north Queensland.
The accident happened during a joint military exercise, about 10km from El Arish, south of Innisfail.
A helicopter ambulance and several road ambulances were rushed to the scene but their services were not needed, a Queensland Ambulance Service Spokesman said.
A defence spokesman said the pilot of the helicopter had been able to make an emergency landing after it struck the power lines while taking part in operation Swift Eagle.
The military exercise had commandoes practising advance force operations such as seizing and holding a sea port.
The spokesman said it was not known yet how many people were on board the helicopter.
"The helicopter got down safely and no one was injured," the spokesman said.
He said an investigation had already begun into the cause of the incident.
Earlier this year six army personnel were injured when a Black Hawk clipped a tree during an exercise near Oakey, west of Toowoomba and crashed.
Australia's worst Black Hawk accident occurred in June 1996 when 18 people died after two of the helicopters collided during a night exercise in north Queensland.
AAP
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The Journos must get a a hundred bucks for every extra word they can add somehow related to the topic and to hell with the sadness they may keep dredging up.
I can hear the Wok Woks mooching around in the dark at the mo. Must be NVGing.
I can hear the Wok Woks mooching around in the dark at the mo. Must be NVGing.
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Yet another wire strike
A Bell 47 flown by the owner has hit a wire on takeoff from his property. The helicopter was based in the Mudgee area of NSW.
It may have caught fire and been destroyed, just out of a complete rebuild. Lots spent. 
It may have caught fire and been destroyed, just out of a complete rebuild. Lots spent.
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I was going to suggest that wire cutter systems should be mandated for all new helos, which is a belief that I hold, but:
After reflection, wire cutters are probably not applicable to this situation. Presumably it is transition from hover, where a helo is very vulnerable to contact with ground/buildings/wires. It is however surprising that he would hit a wire in the immediate vicinity of his home base, but then I don't know the exact circumstances.
Nevertheles, wire cutters provide significant protection from strikes en route and, properly designed, with little impact on payload.
After reflection, wire cutters are probably not applicable to this situation. Presumably it is transition from hover, where a helo is very vulnerable to contact with ground/buildings/wires. It is however surprising that he would hit a wire in the immediate vicinity of his home base, but then I don't know the exact circumstances.
Nevertheles, wire cutters provide significant protection from strikes en route and, properly designed, with little impact on payload.
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EC-130???
Must be USAF if it's true.
The SAAF has C-130's (many marks, B's etc and a couple donated by the yanks...ask Deanw...but not EC-130's). Maybe AAC-130's.
Must be USAF if it's true.
The SAAF has C-130's (many marks, B's etc and a couple donated by the yanks...ask Deanw...but not EC-130's). Maybe AAC-130's.
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Looks like it is true. It was the Eurocopter EC-130 based in the berg. Struck a cable that was set up as part of a slide. Amazing thing is that reports suggest that the ride was "sideways, then backwards etc" and it appears that the driver eventually put it in a field. All walked out. Now the surprising thing is this. During the incident apparently the machine lost a MR blade! How lucky were those guys!!! Man that must have been some ride!
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November 4, 2004
By Barbara Cole
Nothing was going to stop Sally Ingram-Brown marrying Craig Bricknell yesterday, not even a terrifying helicopter crash on the way to the wedding.
And the traumatised, battered and bruised bride finally married her groom after he and priest had to be rescued from the top of a mountain. It all could have ended in tragedy.
The couple, from Durban, wanted a wedding that would make them feel on top of the world and had chosen a romantic spot on Devil's Peak in the Drakensberg.
The small wedding party booked into the Alpine Heath resort where the bridal dinner was to be held. A helicopter based at another resort was chartered to take the priest, the bride's mother, Judy Stead, and the groom's mother, Yvonne Bricknell, up to the wedding venue.
Then the pilot returned to collect the bride, who was decked out in a beautiful wedding dress, her sister Robyn Lambert, who was also her bridesmaid, and her husband Mike, who runs uShaka Marine World, and a photographer, Chris Hearne.
About a dozen people, including tourists, turned out to wave them on their way.
But then they watched in horror as the helicopter lifted, banked right and headed down the valley and straight into a cable (used as a foofy slide) strung between two hills.
As the cable smashed into the glass dome of the helicopter, it sounded like a gunshot, Mike Lambert recalled last night.
The glass shattered and imploded. The cable snapped and then wrapped around one of the four rotor blades. The helicopter began spinning and careered straight down the gorge at high speed.
The bride and bridesmaid were screaming and Lambert was shouting to the pilot to bank to the right. But the pilot, who was desperately trying to stabilise the machine, had lost his headphones and could not hear.
"I honestly thought that my life was about to end. I thought of my wife and children," said Lambert.
The bride said: "It was terrifying. It was the closest I've come to death."
Then, through some absolute miracle they spotted a piece of flat land at the bottom of the gorge and the pilot managed to lift the helicopter almost horizontally to crash land it in the field.
At first the occupants could not get out of the buckled helicopter as the doors were jammed. Then Lambert forced a door open and everyone piled out.
"The rotors were still spinning wildly and we were worried about being decapitated as we crawled away," said Lambert.
Their ordeal had lasted about a minute and left them in a state of total shock . "We couldn't believe it. We weren't even crying."
The pilot said he believed they had been hit by a bird, but Lambert showed him a gash in the helicopter were the cable left its mark.
The onlookers raced to the rescue and a vehicle was sent to return them to Alpine Heath where they were given some strong drinks. The bride had lost her flowers in the crash, her dress was slightly dirty and her make-up had run.
Meanwhile, the groom, the priest and the two mothers were waiting and waiting at the top of the mountain.
The women were becoming distraught as they realised that there must have been an accident.
With no other helicopter in the Drakensberg, Lambert chartered a helicopter from Durban to go and collect them from the mountain and, some four hours later, the worried group was flown back down to the hotel.
Once everyone was assembled, the wedding went ahead but in the Alpine Heath chapel.
"The bride wasn't too keen to get back in a helicopter," said Lambert.
The two Durban helicopter pilots inspected the crashed helicopter and declared it a write-off. "And they told us that if it hadn't been a Eurocopter, which is the safest in the world, we would have died."
By Barbara Cole
Nothing was going to stop Sally Ingram-Brown marrying Craig Bricknell yesterday, not even a terrifying helicopter crash on the way to the wedding.
And the traumatised, battered and bruised bride finally married her groom after he and priest had to be rescued from the top of a mountain. It all could have ended in tragedy.
The couple, from Durban, wanted a wedding that would make them feel on top of the world and had chosen a romantic spot on Devil's Peak in the Drakensberg.
The small wedding party booked into the Alpine Heath resort where the bridal dinner was to be held. A helicopter based at another resort was chartered to take the priest, the bride's mother, Judy Stead, and the groom's mother, Yvonne Bricknell, up to the wedding venue.
Then the pilot returned to collect the bride, who was decked out in a beautiful wedding dress, her sister Robyn Lambert, who was also her bridesmaid, and her husband Mike, who runs uShaka Marine World, and a photographer, Chris Hearne.
About a dozen people, including tourists, turned out to wave them on their way.
But then they watched in horror as the helicopter lifted, banked right and headed down the valley and straight into a cable (used as a foofy slide) strung between two hills.
As the cable smashed into the glass dome of the helicopter, it sounded like a gunshot, Mike Lambert recalled last night.
The glass shattered and imploded. The cable snapped and then wrapped around one of the four rotor blades. The helicopter began spinning and careered straight down the gorge at high speed.
The bride and bridesmaid were screaming and Lambert was shouting to the pilot to bank to the right. But the pilot, who was desperately trying to stabilise the machine, had lost his headphones and could not hear.
"I honestly thought that my life was about to end. I thought of my wife and children," said Lambert.
The bride said: "It was terrifying. It was the closest I've come to death."
Then, through some absolute miracle they spotted a piece of flat land at the bottom of the gorge and the pilot managed to lift the helicopter almost horizontally to crash land it in the field.
At first the occupants could not get out of the buckled helicopter as the doors were jammed. Then Lambert forced a door open and everyone piled out.
"The rotors were still spinning wildly and we were worried about being decapitated as we crawled away," said Lambert.
Their ordeal had lasted about a minute and left them in a state of total shock . "We couldn't believe it. We weren't even crying."
The pilot said he believed they had been hit by a bird, but Lambert showed him a gash in the helicopter were the cable left its mark.
The onlookers raced to the rescue and a vehicle was sent to return them to Alpine Heath where they were given some strong drinks. The bride had lost her flowers in the crash, her dress was slightly dirty and her make-up had run.
Meanwhile, the groom, the priest and the two mothers were waiting and waiting at the top of the mountain.
The women were becoming distraught as they realised that there must have been an accident.
With no other helicopter in the Drakensberg, Lambert chartered a helicopter from Durban to go and collect them from the mountain and, some four hours later, the worried group was flown back down to the hotel.
Once everyone was assembled, the wedding went ahead but in the Alpine Heath chapel.
"The bride wasn't too keen to get back in a helicopter," said Lambert.
The two Durban helicopter pilots inspected the crashed helicopter and declared it a write-off. "And they told us that if it hadn't been a Eurocopter, which is the safest in the world, we would have died."