Helicopter Static Charge?
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static electricity
Recently whilst in New Zealand i had a coversation with a crewman from the venison recovery deer culling days of the 70's. He remembers a number of time being badly shocked with static electricity whilst hooking loads on H500's, some had static straps fitted to stop this. No word of it when I did my hook/sling endorsement a couple of years ago. Any comment??
helibiz
helibiz
Helibiz,
Whoever did your sling endorsment should have covered this. It's a common occurance in sling / winch op's to get static buildup on the line. This static charge will "go to ground" at the first opportunity (ie: through the loadmaster / rescue crewman) if the hook is not grounded before they touch it. Normally, allowing the hook to briefly touch the ground first will cause sufficient discharge, also a well insulated person is less likely to recieve a shock. Dry & dusty environmental conditions will normally make static buildup more likely too.
Whoever did your sling endorsment should have covered this. It's a common occurance in sling / winch op's to get static buildup on the line. This static charge will "go to ground" at the first opportunity (ie: through the loadmaster / rescue crewman) if the hook is not grounded before they touch it. Normally, allowing the hook to briefly touch the ground first will cause sufficient discharge, also a well insulated person is less likely to recieve a shock. Dry & dusty environmental conditions will normally make static buildup more likely too.
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Not only in dry and dusty conditions. It's a real bitch in the snow. We used a length of light bath plug type chain screwed to the skid at the front crosstube. Didn't touch anything on the helo until the chain "landed" otherwise you'd be on your back.
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Zap!
When I started training for my CPL, I was asked to hookup a load for a 206 that was going to do some slinging practice. It was a very cold day and nobody warned me about static electricity. So
when I touched the ring on the net to the hook on the ship I got really zapped. Afterewards when they landed - oh, I forgot to tell you...you've done this before haven't you?
when I touched the ring on the net to the hook on the ship I got really zapped. Afterewards when they landed - oh, I forgot to tell you...you've done this before haven't you?
When Brisbane sank under the waters of a cyclone and a king tide back in 1974, the RAAF was using Hueys from 9 Sqn to rescue people from all sorts of places. One group of 6 was on the roof of a service station, and the rescue crewman went down first, and got a kick from landing on the steel roof.
He stayed there and helped hook the victims into the sling, and each time he grabbed the flailing wire (still cyclonic winds) he got a boot. The worst thing for him wasn't the kick, but the anticipation of what was going to come each time he reached for the hook.
On a nearby roof were two cows, which had swum up there, and when the waters receded, they were still there. I guess they died when they eventually fell off.
He stayed there and helped hook the victims into the sling, and each time he grabbed the flailing wire (still cyclonic winds) he got a boot. The worst thing for him wasn't the kick, but the anticipation of what was going to come each time he reached for the hook.
On a nearby roof were two cows, which had swum up there, and when the waters receded, they were still there. I guess they died when they eventually fell off.
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It is worse on some types than others.
The old Whirlwind gave off a kick powerful enough to drop the winchman to his knees on touching a boat.
Yes, they did make me go down the wire without warning me
The old Whirlwind gave off a kick powerful enough to drop the winchman to his knees on touching a boat.
Yes, they did make me go down the wire without warning me
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In the right conditions (night, dry, etc), you can actually see the static electricity build up on Blackhawks just before touchdown. A little St. Elmo's will develop in a ring on the outer edge of the blades. Usually, this dissipates when the PIC keys his mike. For sling loads, we usually had a grounding hook (attached to wooden pole) that we would touch the line with first... THEN, we'd attach the load.
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Not according to you know who.
To: RDRickster
You had better watch out our othewise you will incur the wrath of NickLappos. He said a visible discharge doesn't happen on the Blackhawk or on other helicopters either.
You had better watch out our othewise you will incur the wrath of NickLappos. He said a visible discharge doesn't happen on the Blackhawk or on other helicopters either.
Last edited by Lu Zuckerman; 7th May 2004 at 19:43.
Killed an aircrewman in the late 70\'s I seem to remember (RN - S61). It was determined after an autopsy that his heart was \'dicky\' and the static did the rest.
It\'s at its worst in damp conditions.
It is now a compulsory briefing point during emplaning/deplaning (under health and safety).
It\'s at its worst in damp conditions.
It is now a compulsory briefing point during emplaning/deplaning (under health and safety).
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A BK117 self incinerated at Buttonville early in the 80's ,there were a whole wack of SB's concerning grounding after that incident. Do composite blades pick up more static than metal ones ?.
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Back in 1963 in Culdrose some static tests were done on a Wessex MK5.
From memory up to 100000 volts were generated in less than 1 second. Obviously the current was minute otherwise I'm sure there would have been some big problems. This meant that after you earthed the hook, if you let go, the static would be back within 1 second. This meant you either had to re-earth or have a line attached to prevent build up.
On one occasion when I was in a low hover, a Royal Marine sergeant jumped out but held onto the door handle. He performed a beautiful double summersault with pike on landing! The build definitely varied with both surface and weather conditions but I don't recall anyone being injured. I've had worse shocks off my car engine spark plug leads.
Small helicopters never seemed to be a problem and thick rubber gloves seemed to do the job.
From memory up to 100000 volts were generated in less than 1 second. Obviously the current was minute otherwise I'm sure there would have been some big problems. This meant that after you earthed the hook, if you let go, the static would be back within 1 second. This meant you either had to re-earth or have a line attached to prevent build up.
On one occasion when I was in a low hover, a Royal Marine sergeant jumped out but held onto the door handle. He performed a beautiful double summersault with pike on landing! The build definitely varied with both surface and weather conditions but I don't recall anyone being injured. I've had worse shocks off my car engine spark plug leads.
Small helicopters never seemed to be a problem and thick rubber gloves seemed to do the job.
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widgeon,
Conductance of structures is an important part of the qualification process, especially with lightening. Look at the bonding straps, and the underlying conductive mesh or film that we use on composites to assure that they behave electrically as if they were metal.
I think that the static electricity build up is a function of the mechanical static charge generation in dry snow or heavy sand. The ground crew should alsways use a grounded insulated wand to draw off the charge when they hook up loads. Letting the hoist hook touch first is also SOP.
The voltage numbers are impressive, it takes 25000 volts to make a spark that jumps 1 inch, for example. But voltage is only the measure of the electrical pressure that has built up, and does not tell us what is the amount of electricity that can flow. The charge (total amount of electricity) is quite small, so the net damage this spark can cause is small.
Really bad cases of charge build-up cause St. Elmo's fire, which is beautiful. I have had this on airplanes in clod dry snow, and it is beautiful but harmless (unless it affects the radios enough to blank nav and comm!)
This subject is often mixed up with the sparks seen on NVG films (or described by NGV wearers). Those sparks are not static caused, they are piezoelectric, caused by the sand crystals emitting when they are bounced off the blades. Crystals do this as their internal electron balance is shuffled when they are deformed. These electrical effects are why crystals are used on the tips of phonograph needles, where their small voltages are amplified as music, for example.
Conductance of structures is an important part of the qualification process, especially with lightening. Look at the bonding straps, and the underlying conductive mesh or film that we use on composites to assure that they behave electrically as if they were metal.
I think that the static electricity build up is a function of the mechanical static charge generation in dry snow or heavy sand. The ground crew should alsways use a grounded insulated wand to draw off the charge when they hook up loads. Letting the hoist hook touch first is also SOP.
The voltage numbers are impressive, it takes 25000 volts to make a spark that jumps 1 inch, for example. But voltage is only the measure of the electrical pressure that has built up, and does not tell us what is the amount of electricity that can flow. The charge (total amount of electricity) is quite small, so the net damage this spark can cause is small.
Really bad cases of charge build-up cause St. Elmo's fire, which is beautiful. I have had this on airplanes in clod dry snow, and it is beautiful but harmless (unless it affects the radios enough to blank nav and comm!)
This subject is often mixed up with the sparks seen on NVG films (or described by NGV wearers). Those sparks are not static caused, they are piezoelectric, caused by the sand crystals emitting when they are bounced off the blades. Crystals do this as their internal electron balance is shuffled when they are deformed. These electrical effects are why crystals are used on the tips of phonograph needles, where their small voltages are amplified as music, for example.
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I managed to poleaxe a camera man whilst passing a film upto my heli in Sweden.
The clearing being covered in snow and hidden tree stumps my wescam cameraman lent out of the door to retreve the film. there was a bang my cameraman had discharged through his finger to the man in the snow. (Bet his girlfriend loves him!). Man in the snow now lying on his back with that look of whats just grabbed my up the **se. (Without the smile)
Now having problems hovering as the crew were laughing so much.
Only after the event did i remember the Dry cold Air effect on Heli's.
Lesson learnt!
The clearing being covered in snow and hidden tree stumps my wescam cameraman lent out of the door to retreve the film. there was a bang my cameraman had discharged through his finger to the man in the snow. (Bet his girlfriend loves him!). Man in the snow now lying on his back with that look of whats just grabbed my up the **se. (Without the smile)
Now having problems hovering as the crew were laughing so much.
Only after the event did i remember the Dry cold Air effect on Heli's.
Lesson learnt!
Howcanwebeexpectedtoflylikeeagles
whensurroundedbyturkeys
It doesn't matter how much emphasis you put on the static problem when briefing a new ground crew, they always forget. Always keen to be the first to catch the hook, the new groundcrewman will reach out, grab the hook then snatch his hand back as the shock hits him- lesson learnt - they don't do it again.
I was caught out myself during a session with 4 pilots doing underslung training. The ground crewman was complaining that despite having a static discharge pole he was still getting shocked. I volunteered to go on the ground and "show him him how to do it". Holding the static pole in my hand, the aircraft (AS332L) came to the hover above my head. I touched the hook with the pole to discharge the static, put the pole down and holding the strop (which was touching the ground) I reached up to grap the hook. Although the aircraft had been earthed less than 5 seconds before, the charge that had built up gave me a hell of a shock. The only way round it was to keep the aircraft earthed with the pole in one hand until the strop was hooked up.
One of the funniest moments was when picking up a package from a site where we couldn't land. We came to a low hover and my crewman leant out the cabin door to pick up the package from a man on the ground. There was a scream from the back as the aircraft's static charge earthed itself. The aircraft had earthed itself across the gap between the crewman's microphone and his lips and then through his body to the man on the ground. My crewman couldn't speak coherently for about ten minutes as he cussed and sweared about the burn on his lips. My ability to hover accurately was totally lost whilst I and the rest of the crew dissolved into hoots of laughter.
I was caught out myself during a session with 4 pilots doing underslung training. The ground crewman was complaining that despite having a static discharge pole he was still getting shocked. I volunteered to go on the ground and "show him him how to do it". Holding the static pole in my hand, the aircraft (AS332L) came to the hover above my head. I touched the hook with the pole to discharge the static, put the pole down and holding the strop (which was touching the ground) I reached up to grap the hook. Although the aircraft had been earthed less than 5 seconds before, the charge that had built up gave me a hell of a shock. The only way round it was to keep the aircraft earthed with the pole in one hand until the strop was hooked up.
One of the funniest moments was when picking up a package from a site where we couldn't land. We came to a low hover and my crewman leant out the cabin door to pick up the package from a man on the ground. There was a scream from the back as the aircraft's static charge earthed itself. The aircraft had earthed itself across the gap between the crewman's microphone and his lips and then through his body to the man on the ground. My crewman couldn't speak coherently for about ten minutes as he cussed and sweared about the burn on his lips. My ability to hover accurately was totally lost whilst I and the rest of the crew dissolved into hoots of laughter.
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I've seen GIs knocked completely off 2.5T trucks by the static charge from CH47s if they failed to discharge the static buildup. It's quite a fall from the top of a fully-loaded truck to the ground, but airborne troops cannot admit pain. 
I used to do lots of sling work in 206s in the GOM, and always briefed the roustabouts about hitting the hook quickly with the becky, but some never learn, and got a jolt even down here in the humidity.
I used to do lots of sling work in 206s in the GOM, and always briefed the roustabouts about hitting the hook quickly with the becky, but some never learn, and got a jolt even down here in the humidity.
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A little spark will go a long way...
Some helicopters are designed so that the static buildup on the rotor blades is carried directly to the airframe bypassing the transmission. On some helicopters that have elastomeric teeter bearings the charge can not get to the airframe nor can it pass through the transmission. This is true for the Cobra models like the AH1-J and the Bell 214. On these helicopters the static charge forms a torroidal magnetic field around the rotor disc with this field centered on the main mast. This causes magnetization of the mast and the steel parts on the rotorhead. This can also happen on the Bell 412. The level of magnetization is far in excess of that allowed in the Bell overhaul manuals when a part is Magnafluxed and then degaussed. This can result in minute electrical charges flowing across gears and bearings in the transmission causing spark discharge erosion. This also happens on those helicopters where the static charge is drained to the fuselage through the transmission.
Last edited by Lu Zuckerman; 10th May 2004 at 03:14.
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Helicopter Static Charge?
I was watching one of those most amazing video shows and they showed a helicopter doing a rescue from a car that was stuck in a flood. As the guy got off the helicopter and on the car then got back on it said he got shocked a little because the helicopter builds up a static charge. What's the deal with this? It was an MD500 if that makes a difference.
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No I dont think its a 500 thing, just a helo thing.
When I was required to repel from helos both Huey's and Blackhawkes & get winched into them, we were always reminded to make sure that the shackle was stomped into the ground to discharge the static built up by the rotors.
If we didnt ground it enough, we would recieve one hell of a kick that removed any feeling of that hand/arm/shoulder for a few days.
Some times there would be more static or it built easier when the air was dry and dusty ( Australia you say ...no.. really? ) and that also made it harder to earth by stomping it into the ground.
Some times the Loady would yell/ hand signal at us to ensure we kicked the **** out of it so that we wouldnt get shocked.
Some times one of the boys was a little too impatient to kick it in good and would pay the price.
It happens when you have a lot going on and your on a warm excersise simulating that 2 way rifle range.
( it can happen when the ground is really dry and doesnt conduct so well ).
I have not been booted but can attest to friends not being able to hold their own rifle/kit and complain about their hand etc throbbing really bad and loadies like a school boy.
No burns that I saw, just a lot of un happy chappies.
I made the mistake when in briefing of asking pilots what happens to us when we are being slung underneath and they have an engine failure ( 1 or both depending on how many it had ) and the answers were always " Don't worry mate, we will look after you".
See now being under the helo at 50 odd foot and us being more than 50 off the ground always made me think that we are going to get an early flying lesson as no one would ever tell me what their plan was.
I assumed we would be cut away and they would attempt an auto ( whilst being right in the middle of the HV curve) & hopefully the spinning separating parts are further from us.
Any one able to elaborate on this?
Cheers HF
When I was required to repel from helos both Huey's and Blackhawkes & get winched into them, we were always reminded to make sure that the shackle was stomped into the ground to discharge the static built up by the rotors.
If we didnt ground it enough, we would recieve one hell of a kick that removed any feeling of that hand/arm/shoulder for a few days.
Some times there would be more static or it built easier when the air was dry and dusty ( Australia you say ...no.. really? ) and that also made it harder to earth by stomping it into the ground.
Some times the Loady would yell/ hand signal at us to ensure we kicked the **** out of it so that we wouldnt get shocked.
Some times one of the boys was a little too impatient to kick it in good and would pay the price.
It happens when you have a lot going on and your on a warm excersise simulating that 2 way rifle range.
( it can happen when the ground is really dry and doesnt conduct so well ).
I have not been booted but can attest to friends not being able to hold their own rifle/kit and complain about their hand etc throbbing really bad and loadies
like a school boy.No burns that I saw, just a lot of un happy chappies.
I made the mistake when in briefing of asking pilots what happens to us when we are being slung underneath and they have an engine failure ( 1 or both depending on how many it had ) and the answers were always " Don't worry mate, we will look after you".
See now being under the helo at 50 odd foot and us being more than 50 off the ground always made me think that we are going to get an early flying lesson as no one would ever tell me what their plan was.
I assumed we would be cut away and they would attempt an auto ( whilst being right in the middle of the HV curve) & hopefully the spinning separating parts are further from us.
Any one able to elaborate on this?
Cheers HF
