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JaredYng
23rd Jan 2008, 05:15
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.

Thanks

HELOFAN
23rd Jan 2008, 05:42
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 shit 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 :E 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

Scissorlink
23rd Jan 2008, 06:05
Saw the spark once when in drizzle conditions the ole mate on the ground hooked me onto a load in the MD500 ...didn't laugh honest !!:oh:


SL

Ascend Charlie
23rd Jan 2008, 10:10
Yes, the kick is real. Doing flood relief, we winched the rescue crewy down to a rooftop, and he then had to load the stranded people onto the hoist each time we sent the horse collar down to him. In the drizzling rain, he got a huge kick every time the collar came down - he had to grab it in the gusty winds, no chance to let it earth itself.

He took it 6 times in that sortie, we recommended him for a bravery award at the end of the week and he was rewarded with a medal.

On the other question about a "tea-bag" when the engine fails:
The briefing was to let the tea-bag touch the ground, then use the cable cutter to let him go, so he won't get dragged away by the aircraft.:sad:

That's assuming the aircraft predicament allows enough time for the crewman to operate the cutter before other things overtake him.

ericferret
23rd Jan 2008, 11:38
Working on a Lama operation in Scotland I watched in horror as a new loader (Australian)
was catching the incomming ag buckets on a very wet day . His eyes were almost lighting up and his hair was standing on end.

I went to tell him to desist and allow the buckets to earth out before touching them.

I was stopped by the other loaders (New Zealanders) who apparently had told him that they all had to do it and were enjoying the show!!!!!!!!!!!!!!!!!!!!!!!!


Wet humid days are the worst and composite blades seem to generate a larger charge than metal.

The worst shock I saw was caused by a 365C which was enough to throw the loader several feet.

(Addition)

I spoke to the guy who got zapped above. It was actually an S58T that did the damage (shows how the memory plays tricks). He said that it felt like he had been hit by a pickaxe handle. Apparently the 58 would build up static so fast that just earthing it out momentarily would not work.

rotornut
23rd Jan 2008, 11:44
When I was doing my training I volunteered to hook up a sling to a 206 on a very cold winter day. Even though I had gloves on I got a real jolt when the hook on the machine touched the ring on the line which I was holding.:{

23rd Jan 2008, 20:29
No one ever heard of using a zapper snapper then? A simple piece of wire attatched to the winch hook that dangles below the winchman to dissipate the static before he does.

3 o'clock
23rd Jan 2008, 21:36
The charge varies with helicopter size and ambient conditions. When there is lots of dust in the air, rain or high humidity the chances of being shocked are much higher due to the increased friction. But operating with a mid sized helicopter like a S76 the average shock rarely exceeds something you may get off a car door. Being paranoid about the shock off a wire is not smart if you are in the water awaiting rescue as you may only get one chance to grab the strop in bad weather, and waiting for it to be earthed nicely alongside you may take a while.
The technique of ‘stomping’ the hook into the ground with your foot will certainly remove a charge, but is not the best practice for a very thin piece of live saving wire that is about to haul you to safety.
Watching three crew members in a submarine conning tower back away from my out stretched hand one day would have been amusing had I not known how hard the boys were working to get me onboard in the reasonable swell and fading light. After about the fourth swing past and one smash into the side of the conning tower, I pulled a shot-bag from my leg pocket that was connected to 15’ of H.I. line. I hurled this at the occupants and when it bounced off one of their heads and into the tower I yelled, “its [email protected]<hidden>@<hidden> well earthed now!” The bloke we were going to get was then recovered with just a few more heartbeats depleted.

slingyerhook
23rd Jan 2008, 22:27
Try using a section of broom handle,with 4-5 ft of thin chain attached.As the hook comes in,make sure the chain is touching the deck,with the pole making contact with your hook etc BEFORE grabbing it,or guess what.......you'll end up like the ready brek man!,especially in hail/damp conditions.:eek:

syh.

Backward Blade
26th Jan 2008, 21:44
Just reading the title of this thread cracked me up!! I spent 8 years logging/fighting fire underneath helicopters in BC Canada in everything from 206, A-Star, 500, K-Max,61, KA 32, 107's etc. Especially in the rain or with thunderheads nearby it got really bad. Sometimes under the bigger machines, a perfectly delivered hook would arc at you from 6 or more feet! would put you on your knees sometimes. Turned out in that kind of crazy work it was a right of passage...when the machine costs so much, you better hook up asap!

With experience you would find that sometimes the 5-6 foot chain dangling from the bottom of the hook would fall/rip off throught the timber...you would learn to set yourself up in or nearby a bush and let it hit that first and then quick as a bunny lunge toward the hook. Sadly not even that worked all the time. It got really funny with the rookies when they got their first arc...they would arc out and then pull back, only to let the hook charge up again and BAM. repeat as necessary LOL.:} You knew it was really bad if you were in blowing snow and you could sometimes not see the helicopter 1/2 a klick away but you knew where he was cause of the blue arc nailing the guy on the ground!!! Show's up really well in the snow.:eek:

Last but not least try this...often when breaking in a new hooktender and finally letting him at the hook we would wait untill a good wet rainstorm. We would set him up high and in the open on a big stump with a handfull of steel chokers in his hand.:E Being the keener he usually was (including yours truly) he would slam those chokers towards the hook only to get blown off his feet by the charge. It was funny back then. The saying always went "Real Men Take the Arc!" :ugh:

Those times have since past and I being a responsible pilot towards my customers, always remind them of the tricks I learned then cause boy o boy do they get pissed when they get a kick! I'll put it on the ground too sometimes, especially when it's really dry, or really snowy.:) Customer relations and all that

BWB

27th Jan 2008, 08:18
I guess there is no Health and Safety Executive in Canada then:)

SASless
27th Jan 2008, 15:33
Crab old Man,

The Nanny State syndrome does not exist in all parts of the world....and as is proven by many posts here.....we continue to thrive and even enjoy a bit of a laugh while at our workaday employment.:rolleyes:

JaredYng
28th Jan 2008, 19:24
If you were a swimmer in water being rescued and the hook touched the water would the shock be great enough for you to feel it just by being in the water?

Breeze 29900
30th Jan 2008, 02:20
If your the one being rescued, you wouldn't feel the zap unless the hook / basket hit you first. The zap is not that strong as to travel to body in the water.

If you are the rescuer on the hook going into the water and the conditions are right for increased static electricity, you will feel it. Some times you might even bite through your tongue as a result of the zap.

Beware!

A zapper snapper is a good idea when the conditions warrant it. (Have been using our three metre length of old hoist cable for years but never had a name for it until now - Thanks [email protected]<hidden>)

Regards
Breeze

Winnie
30th Jan 2008, 14:58
A friend of mine in Norway who used to fly Lynx Mk. 86's once told me a story of a SAR Swimmer who was jumping out of the machine in a low hover to straighten the main wheels for taxiing.

He forgto to undo his helmet cord, and promptly started jumping up and down with a "AHHH!" every time he hit. And the helicopter was hovering in nice wet snow falling...

My friend was struggling to keep the helicopter in control as he watched the SAR swimmer keep up his show, until the F/E got the cord unhooked...

He did survive it tho.


As to Canada and Health and Safety in the workplace, it seems that "production" and "Speed" are more important than safety sometimes. Have on numerous occasions mentioned the "broomhandle with cable touching the hook and ground", but have been over-ruled as it seems this would take valuable seconds away from the work...

Cheers
W.

Backward Blade
31st Jan 2008, 13:44
Easy there Winnie,

What I expressed were my experiences as a young lad doing a job which very few do or have done, nor do I recomend it in my later years (just a few more than you but not by much) We were by no means special forces but tough bastards all the same and earned our money the hard way. After 8 years I only know of one man that died doing it on the ground and it was NOT from the "arc". On the other hand I know a few pilots that have passed on doing anything but "production" work as most of us here do. To put it bluntly my experiences on the ground are by no means a reflection of the aviation (ie Pilots/Engineers) community in Canada and our commitment to safety. It was not my intent to give you all a false representation of a cowboy attitude. It's just that a few of us that have worked both sides have a different perspective as I bet your SAR Tech does now after his experience.

Fly Safe All

BWB

Winnie
31st Jan 2008, 14:36
Apologies to you BWB, I did not put it clearly that those were my opinions, not reflections on you!

I meant as a sweeping generalization that things here (and in my country of origin too unfortunately) production, fast, quick are words that go before safety and comfort.

I know nobody has been killed because of static discharge, but it is DARN uncomfortable, and can be easily avoided. But that takes time.

Again, sorry, not directed at you.

Cheers
Winnie.

Backward Blade
31st Jan 2008, 15:29
Point taken and thanks

BWB

Dis-Mystery of Lift
31st Jan 2008, 20:05
We were lifting 40ft Containers in East Timor with the Mi26 and had a few Local guy's trained(As best we could) to do the hook up's. One of the boys forgot to ground the hook and it Blew him off the container and straightened his Curls...Very Funny!!!:):):)

floatsarmed
31st Jan 2008, 22:19
In the AAC we used a home made hook, cable and spike system where as the loader gets under the machine he simply whacks the spike into the ground under the machine and puts the hook over the back of the skid thereby grounding the aircraft prior to hooking up the load. If we didn't have one then you just hang onto the plastic sheathing on the stropp and touch it to the hook first before touching the machine. Once saw a RAF loady get zapped off the top of a truck by a Chinook - not funny!!!!:eek:

oberons knob
14th Feb 2008, 20:40
In submarines we used to do helo transfers to the top of the fin (conning tower to non submariners). We had to have a man with an earthing pole grounded to the boat to remove the static charge from the winch cable before the person being winched touched the metal submarine. If we really didn't like the person on the winch strop all sorts of offers of money beer and rum would be made to the man with the earthing pole to touch the visitors leg, body or delicate areas with the pole, causing the charge to be earthed through the body part touched and thus extreme agony in the nether regions for the next week or so! :D

What Limits
27th Apr 2009, 22:00
Anyone know of any good online articles explaining this phenomenon.

I am researching this as one of our aircraft suffered a big discharge the other day causing some damage.

Hedge36
28th Apr 2009, 04:28
Your ground hook is your friend.

http://hedge36.smugmug.com/photos/141347179_Jb43s-L.jpg

unstable load
28th Apr 2009, 05:25
I have hooked loads onto the S61 on land and ships and in conditions ranging from hot and dry to cold and wet and found the "best way" to handle the shock if a ground pole was not available was to grab the strop as firmly and as hard as you could.
It still bites:eek: but not as bad as tip-toeing around the spark.

Adam Nams
28th Apr 2009, 10:48
Quite agree - suck it in man! Grab it quick - what are you a man or a mouse?

Always a pleasure using the old chain, cable, hook method to ground the aircraft. Even better if you managed to convince the u/t pilot "helping out" that the best way to make sure that he didn't trip over the chain ........ was to put it in his pocket. :E


eeeeeek eeeek eeeeeek

John R81
28th Apr 2009, 12:28
What limits

I think the physics is quite simple. Just like rubbing a balloon on your jumper, really. If it is simple, then........ (if not simple then someone who knows what they are talking about will be along shortly!)

The rotating blades impact molecules (like balloon and jumper) and the impact knocks electrons off the outer orbit of an atom. That molecule becomes + charged and the roter takes on a - charge. The one molecule is left behind, but the rotor hits more molecules and so builds a bigger - charge. The - charge then affects the whole airframe.

When the potential difference between the machine and earth is greater than the resistance of a path between the two, a spark runs up from the ground to the machine along the path of least resistance, earthing the charge on the machine. The longer between earthing, the more molecules to hit (eg rain) etc the bigger the - charge built on the airframe before earthing.

The spark has very high voltage but no amps - it is static electricity. Hence a BIG impact felt if it earths through the loader with little damage. The charge can get big enough, however, to create spark erosion type damage at the point where the charge earths from the airframe. I would guess that damage to electric components is theoretically possible if the charge is big enough but the size of the charge would be getting towards "Lightning" (same process) value.

cockney steve
28th Apr 2009, 15:50
The helicopter effectively forms a Faraday Cage around the electronics.

Same as a F.W. aircraft,= damage is extremely remote.
In-service aircraft are hit by lightning every day, somewhere in the world.

Damage is usually due to broken bonding straps between surfaces.

How come Helo's don't have "wicks" to dissipate the charge?

Winch-control
28th Apr 2009, 16:31
Hmm I have managed to weld the static discharge lead to the deck of the ship that I am landing on, and have been in the un envious position of being unable to grab the rails of a boat... Got it ..nah shock... got it nah shock....got it nah shock.... lots of times! Static discharge leads do work, but I have been defibed more times than I care to think about!

unstable load
29th Apr 2009, 14:13
cockney steve,

Helicopters do have static discharge wicks.

206Fan
23rd Nov 2013, 16:59
We were lifting 40ft Containers in East Timor with the Mi26 and had a few Local guy's trained(As best we could) to do the hook up's. One of the boys forgot to ground the hook and it Blew him off the container and straightened his Curls...Very Funny!!!
I was watching a show on documentaries earlier called "X-Machines". Showed the Mi-26 lifting a container in Alberta and moving it to a building site. The commentator said the 26 can build up 4 Million Volts of Static. Insane!

Hughes500
23rd Nov 2013, 18:06
I find it depends upon weather . have been using a 500d for brash lifting here in Uk. Have moved 10000 bags 4 to 5 at a time, haven't had a belt at all although we haven't been flying in wet weather which normally seems to generate a charge

Thomas coupling
23rd Nov 2013, 18:07
During a winchex in the 80's from a Sea King the winch man we were collecting after the first cct grabbed the harness assembly before it grounded. He collapsed and his heart stopped. He was resuscitated eventually and went on to a fullfilling career. They estimate a charge in excess of 40,000v can be generated in the right circumstances but obviously only with a small amperage.

I haven't heard of any (professional) unit that winches/hoists/sling loads without an earthing strop? :ooh:

Jack Carson
23rd Nov 2013, 19:42
The static discharge from the C/MH-53E is very significant. The ground crews use a Sheppard’s hook with a grounding wire to ground the aircraft prior to touching the hook during load hook ups. The system also incorporates a grounding wire from the hook up the pendant providing a path into the airframe. There was at least one instance where the ground wire became detached as the pendant stretched during a 32,000 lb lift. In this case the crewman in the aircraft with his hand on the mechanical hook release was knocked on his butt.

SASless
23rd Nov 2013, 20:00
The Chinook in dusty conditions builds a bit of Static.....well actually....enough to replicate Lightning almost.

In the infinite wisdom of the US Army, some innovative folks once put a static discharger on the side of the fuselage which was supposed to safely discharge static buildups.

There was a Pilot operated set of switches for operating the system and the default position on the ground was of course the "Off" position.

As Sod's Law prevails in the US Army (oh but doesn't it!).... along trods a young Soldier heading to his Bunker on the Flight Line to pull his Night Sentry Duty and like a Bolt from the Blue.....a huge arc of fire and brimstone flashed from the parked Chinook...to his Steel Helmet and then to ol' Mother Earth.

Wiser heads prevailed and the Static Discharging Systems were all removed from the Fleet.

A Golden Rule while hooking up sling loads.....always touch the lifting tackle to the Hook.....never hold the lifting tackle in one hand and touch the cargo hook with the other hand.....as it will sometimes be a thrill.

206Fan
23rd Nov 2013, 20:30
Video showing the discharge from a bucket. Bell 212?

K3djcxUCcvQ

TRC
23rd Nov 2013, 22:48
Jared, you have PM.

Savoia
24th Nov 2013, 09:21
In Papua New Guinea, late 80's, we had a ground-handler who had been working loads for about a week before he encountered the 'hook of shock'!

He was pretty efficient at hooking-up loads and would waste no time in reaching-out for the hook in order to slide the D-bolt 'shackle' (attached to the load ropes) through the hook's keeper.

As was the norm for the PNG highlands, rain showers abounded, and with less manoeuverability than would be so without a load, one sometimes couldn't avoid penetrating the edges of the lighter showers.

Returning from such a trip I sailed in to uplift a new load when upon arrival I saw the loadsman jump back after grabbing the hook followed by a sharp glance skywards where, even from 100ft, it was clear to see that he was not pleased.

Pressing on, the load was hooked-up and, 20 or so minutes later I was back for more when to my surprise the loadsman had armed himself with a stick and was now stabbing at the hook in a display which reminded me of the staircase sword-fighting scene between Errol Flynn and Basil Rathbone from 'The Adventures of Robin Hood' (1938).

It have to say that I had a wee chuckle at his expense but, thereafter landed and explained to him that the present weather was building-up a charge on the aircraft (not that I think he understood this) and that he should allow me to 'ground' the hook before he grabbed it.

On his day off he turned-up at the exploration camp in his full tribal regalia and of which visit I have a photo somewhere!

oldgrubber
24th Nov 2013, 09:30
I remember preparing for a RAS evolution from "Lusty" to some support vessels many years ago when I was the deck Supervisor for a MK6 sqdn. I duly briefed the lads on their duties and we got started. It was only when the lad was about to hook the sacru hook with his earthing pole that I noticed he had the earthing plate in his jacket pocket! Luckily I got to him before the helicopter.
Not strictly on topic but another incident back at Culdrose many years ago consisted of spotting an earthing cable from a static fuel dispenser on 706 sqdn line (being used) knotted together. The lad fuelling the aircraft said the tractor had driven over it and had snapped it so he "fixed" it to complete the refuel!!

Jack, you gotta love him.

Cheers


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