Ditching a helicopter: (incl pictures)
Gatvol
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As to the above post in reference to the U.S. Coast Guard. You can start here: www.uscg.mil
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I've heard that if you use lateral cyclic to stop the blades the force of them stopping so quickly can rip the MR gearbox into the cabin. Any truth to this? It was discussed concerning an r22
I have always heard that you should use right lateral cyclic upon touchdown in CCW rotating helicopters, so that if the gearbox is gets ripped loose its going to move aft and away from the cockpit!
Iconoclast
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Dislocating the main transmission.
In my post above about ditching the HOS-1s I do not believe they experienced a transmission breaking loose. On that helicopter type the blades had a main tubular spar and ribs and were covered in fabric.
There was greater danger if a blade hit the ground in a roll over the balancing weights (lead shot) would spray out as if shot from a gun.
There was greater danger if a blade hit the ground in a roll over the balancing weights (lead shot) would spray out as if shot from a gun.
Avoid imitations
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Landing across the swell (along the length of a wave) is supposed to be smoother and should prevent a nose-down surf into a wave trough.
Manufacturer's ditching advice for the S-70 as I recall, (no floats on ours then), is to deliberately roll the aircraft over (to the right?) in a positive and controlled fashion before the rotor slows to the point where it's no longer flying.
I think this is to make events more predictable than if the rotor is left to it's own devices in the final few moments. The drag of the water will stop the rotor very quickly so the next part, the crew evacuation, can begin asap before the aircraft sinks too deep.
Manufacturer's ditching advice for the S-70 as I recall, (no floats on ours then), is to deliberately roll the aircraft over (to the right?) in a positive and controlled fashion before the rotor slows to the point where it's no longer flying.
I think this is to make events more predictable than if the rotor is left to it's own devices in the final few moments. The drag of the water will stop the rotor very quickly so the next part, the crew evacuation, can begin asap before the aircraft sinks too deep.
From memory as a waterbird instructor:
Normally, you won't have time to do anything else but land as gently as possible at the bottom of your engine off, in a single. Any thought about landing cross swell, etc will not be an option because you won't be able to time the moment of impact!
With a twin, unless it is fuel contam when both engines stop, you'll have time to consider most of the variables.
Aim of the game is to reduce touch down speed to a minimum! Everything else is secondary.
Picking your touch down point to be across swell is by far the best. never attempt to land into or behind the swell, you'll lose all semblance of control.
IF you have the wherewithall then consider tail first to cushion the landing - but this can be a harsh option if you are able to land with little or no fwd speed where you can simply 'plonk' it onto the water, almost vertically.
There are some schools of thought about putting the advancing blades in first so as to encourage the MGB to depart aft should it feel like it!! [opposite and equal reaction]. But one needs to remember that this action could deposit the MGB in the crew cabin aft too!!
Of course any fancy manouevres need only be considered in a sea state 3 and above. Below this, simply flare it to a full stop immediately above the relatively calm sea and overpitch vertically.
Get rid of as many emergency exits, JUST PRIOR TO ENTRY, any earlier and they could go thru the main / tail rotors and spoil your perceived flight path! Relying on emergency doors after entry into the water is dodgy to say the least because you may have buckled the airframe and the doors may jam.
Once on the water, and in a sea state >2, expect a blade tip strike and consequent roll over due to swell.
ALWAYS attempt to land as close as possible to the wind direction accepting cross swell landings.
DO HUET often and pay close attention to what the instructors tell you. A HUET course in the Uk is only £180/person and worth its weight in gold.
Normally, you won't have time to do anything else but land as gently as possible at the bottom of your engine off, in a single. Any thought about landing cross swell, etc will not be an option because you won't be able to time the moment of impact!
With a twin, unless it is fuel contam when both engines stop, you'll have time to consider most of the variables.
Aim of the game is to reduce touch down speed to a minimum! Everything else is secondary.
Picking your touch down point to be across swell is by far the best. never attempt to land into or behind the swell, you'll lose all semblance of control.
IF you have the wherewithall then consider tail first to cushion the landing - but this can be a harsh option if you are able to land with little or no fwd speed where you can simply 'plonk' it onto the water, almost vertically.
There are some schools of thought about putting the advancing blades in first so as to encourage the MGB to depart aft should it feel like it!! [opposite and equal reaction]. But one needs to remember that this action could deposit the MGB in the crew cabin aft too!!
Of course any fancy manouevres need only be considered in a sea state 3 and above. Below this, simply flare it to a full stop immediately above the relatively calm sea and overpitch vertically.
Get rid of as many emergency exits, JUST PRIOR TO ENTRY, any earlier and they could go thru the main / tail rotors and spoil your perceived flight path! Relying on emergency doors after entry into the water is dodgy to say the least because you may have buckled the airframe and the doors may jam.
Once on the water, and in a sea state >2, expect a blade tip strike and consequent roll over due to swell.
ALWAYS attempt to land as close as possible to the wind direction accepting cross swell landings.
DO HUET often and pay close attention to what the instructors tell you. A HUET course in the Uk is only £180/person and worth its weight in gold.
"Just a pilot"
Everybody I've ever talked to who'd done this "actual," flared and pulled pitch higher than they thought they were. The water's a very poor surface to judge altitude from. I'd guess that all the fancy talk of rolling left, right, landing on the crest, etc. is not realistic- falling from 10+ feet with decaying RPM is going throw the timing and effect off.
SO- I'd do a HUET for sure.
I'd want floats.
I'd have my vest and survival gear on at all times.
I'd prebrief everybody and hope they're adequately trained.
With small seas running, I'd go into the wind and ZERO forward motion at touchdown, and parallel the swells if they're significant, with ZERO forward motion at touchdown.
ZERO forward motion, I think is the prime consideration. It's important enough that I'd ditch with power if ditching was certain rather than risk the trend to fall from height. It'd be tough, but sometimes there are no good answers, only some better than others.
Hitting with forward momentum will tend to bring the heavy and rotating stuff into the cabin and that's very bad.
ZERO forward momentum, more than rolling left, tail first etc. is my aim. Hitting with minimum vertical impact would be next consideration.
Having the doors open is a nice thought. The pilot flying probably won't have time, and the pax will probably be involved in cinching tight, etc., so be prepared to jettison underwater and/or kick panels out...
SO- I'd do a HUET for sure.
I'd want floats.
I'd have my vest and survival gear on at all times.
I'd prebrief everybody and hope they're adequately trained.
With small seas running, I'd go into the wind and ZERO forward motion at touchdown, and parallel the swells if they're significant, with ZERO forward motion at touchdown.
ZERO forward motion, I think is the prime consideration. It's important enough that I'd ditch with power if ditching was certain rather than risk the trend to fall from height. It'd be tough, but sometimes there are no good answers, only some better than others.
Hitting with forward momentum will tend to bring the heavy and rotating stuff into the cabin and that's very bad.
ZERO forward momentum, more than rolling left, tail first etc. is my aim. Hitting with minimum vertical impact would be next consideration.
Having the doors open is a nice thought. The pilot flying probably won't have time, and the pax will probably be involved in cinching tight, etc., so be prepared to jettison underwater and/or kick panels out...
Senis Semper Fidelis
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We disscussed this in a thread about three months ago, and I mantioned my pal who put down a B206 into the salty stuff between EGNH and the IOM,
to quote the man
" I just had enough time to get out of the already unlatched door, after splashdown by undoing the belt at that moment, I then kicked away from the heli which was turning over and showing its skids"
So time is definatly " Tempus Fugit" possibly time to relate on your insurance policy
to quote the man
" I just had enough time to get out of the already unlatched door, after splashdown by undoing the belt at that moment, I then kicked away from the heli which was turning over and showing its skids"
So time is definatly " Tempus Fugit" possibly time to relate on your insurance policy
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If you are in the fortunate position to find a company (not many companies have fixed floats) to do a float endorsement and the company conducts touchdown autos to the water, this will assist in judging approach speeds, flare heights and picking swells etc.
HUET courses are worth more than their weight in gold.
Lifejackets that double as survival vests with a minimum of ELB, mini flares, fluorescent marine dye marker, floating torch, good quality fixed bladed knife and a small oxygen bottle (spare air) for those vital extra seconds.
HUET courses are worth more than their weight in gold.
Lifejackets that double as survival vests with a minimum of ELB, mini flares, fluorescent marine dye marker, floating torch, good quality fixed bladed knife and a small oxygen bottle (spare air) for those vital extra seconds.
I don't want to be the best pilot in the world - Just the oldest
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Emergency Floats and stability
Just wondering if one of the rotorheads can steer me in the right direction for some info.
During a HUET course I was conducting today one of the students asked me about whether any specific data relating to maximum sea state that say an S76 or AS365 could expect to remain upright upon ditching was available. Those two types are fairly common here in Angola. I could not really answer it with any info based on authoritative sources except for what I have read and that is that on emergency floatation, most helicopters will be fairly unstable.
Things like the control of the landing/impact on the surface, whether or not pax panic and rush to one side, whether the airframe remains headed into wind and waves and whether all the floatation cells function correctly are some of the factors I could come up with.
Anyone know if there is any documented study of this subject?
Thanks in advance
IJ
During a HUET course I was conducting today one of the students asked me about whether any specific data relating to maximum sea state that say an S76 or AS365 could expect to remain upright upon ditching was available. Those two types are fairly common here in Angola. I could not really answer it with any info based on authoritative sources except for what I have read and that is that on emergency floatation, most helicopters will be fairly unstable.
Things like the control of the landing/impact on the surface, whether or not pax panic and rush to one side, whether the airframe remains headed into wind and waves and whether all the floatation cells function correctly are some of the factors I could come up with.
Anyone know if there is any documented study of this subject?
Thanks in advance
IJ
Gatvol
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As to exact Studies Im no help.I do think by using the internet you may find some information that will be of use. I suggest downloading a free Search Tool that utilizes many Search Engines at once. www.copernic.com
Site I would look to may be the Navy or Coast Guard. They live on the water and that is a big concern of theirs. Try www.navy.mil or www.uscg.mil
Having a few hundred hours overwater its also been a concern of mine albeit I flew different helos. In conversations items that came up were will they rip off in Autorotation/ Hitting the water etc. Experience of a room mate on one day out of 365 where he had calm water and close to shore. He had an engine failure in a B206 and put it down perfectly in the water off St Croix. They towed it to land.
Good Luck and if your in Angola, the water is probably prefered over walking through the Minefields.......
Site I would look to may be the Navy or Coast Guard. They live on the water and that is a big concern of theirs. Try www.navy.mil or www.uscg.mil
Having a few hundred hours overwater its also been a concern of mine albeit I flew different helos. In conversations items that came up were will they rip off in Autorotation/ Hitting the water etc. Experience of a room mate on one day out of 365 where he had calm water and close to shore. He had an engine failure in a B206 and put it down perfectly in the water off St Croix. They towed it to land.
Good Luck and if your in Angola, the water is probably prefered over walking through the Minefields.......
The BHT-222U-FMS-12 says that the emergency flotation should keep the helicopter stable in up to Sea state 6 which is 25 kt wind and waves up 2.5 to 3.4 m height.
I presume that the B-222 is unusally stable compared to many other helicopter types due to the emergency float layout. The main floats are positioned outboard on the stub wings under the wing end cover.
I presume that the B-222 is unusally stable compared to many other helicopter types due to the emergency float layout. The main floats are positioned outboard on the stub wings under the wing end cover.
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It's a very int eresting question and I would like to know if anyone finds any major statements of the basic stability performance of offshore helos. On the whole I think it is one of those areas where manufacturers do what the aviation regulators require (i.e. not much). The military sounds like a good source - if it is accessible!
If you look at real ditchings, the way that the helicopter enters the water will always make a big difference to the outcome, pretty much regardless of the water stability of the thing when it is turned into a boat.
If you look at real ditchings, the way that the helicopter enters the water will always make a big difference to the outcome, pretty much regardless of the water stability of the thing when it is turned into a boat.
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if anyone is interested apical industries has an excellent video available of various full on autos of emergency float equipped aircraft, mostly light single turbine, the heaviest being 902.
also keep in mind their is a significant difference between a ditiching float system and an emergency float system with regards to bouyancy requirements.
as for water stability the float style itself will have a significant effect of the ability of the airframe to remain upright. tri-bag systems have a much greater footprint and provide greater stability.
dr
also keep in mind their is a significant difference between a ditiching float system and an emergency float system with regards to bouyancy requirements.
as for water stability the float style itself will have a significant effect of the ability of the airframe to remain upright. tri-bag systems have a much greater footprint and provide greater stability.
dr
I'm surprised one of the canadian mil pilots hasn't come forward with this topic, they are the waterborne experts during their training.
Anyway, I'm sure I mentioned it somewhere yonks ago, it may even be in this thread, but can't be bothered to read thru it, so here goes:
I was a waterbird instructor for my sins during my exchange with the RCAF. It was our job to throw S61's at the water from all angles and even try to fly away after!
Bearing in mid that the S61 has a 'boat hull', if anything is going to remain stable on the water, this is the a/c to be in. I would suggest that anything else is less stable and will suffer the following consequences, more readily:
It is assumed that there is going to be no attempt to take off again!
1. Integrity of airframe affected depending on design. This means that water will flood the a/c faster or slower, depending on how well the a/c has been put together! Large quantities of water sloshing around the insides of the a/c will exacerbate uncontrolled instability, eventually leading to a top heavy a/c 'tipping' over.
2. If the rotors are still turning (quickly), they will strike the swell in anything >SS3. This could result in tipping the cab over or serious structural damage (not a problem if you intend to scrap the airframe after).
3. Water ingress will very very quickly affect the electrics. The most obvious problem being unable to communicate with the passengers/crew. This is by far the most serious issue especially when/if the cab turns over!
4. If the flot bags don't deploy evenly, the cab will sit skewed off to the swell / sit at an awkward angle and further exacerbate the eventual overturn.
5. If the drogue shute isnt deployed, the a/c will sit side onto the swell and within minutes, she will turn over in anything >SS4/5.
6. The worst I've heard of is SS6 and the a/c remained upright and pointing in the right direction for long enough to be recovered. The swell though was a long one and not too choppy.
The worst thing is thinking about all those people down the back while you are doing everything in your power to keep the ***er from tipping over! If she goes....God help the pax! At least you've got jettisonable doors and STASS and HUET training and correct gear and radio and ELT and and and.....
Don't go there.
Anyway, I'm sure I mentioned it somewhere yonks ago, it may even be in this thread, but can't be bothered to read thru it, so here goes:
I was a waterbird instructor for my sins during my exchange with the RCAF. It was our job to throw S61's at the water from all angles and even try to fly away after!
Bearing in mid that the S61 has a 'boat hull', if anything is going to remain stable on the water, this is the a/c to be in. I would suggest that anything else is less stable and will suffer the following consequences, more readily:
It is assumed that there is going to be no attempt to take off again!
1. Integrity of airframe affected depending on design. This means that water will flood the a/c faster or slower, depending on how well the a/c has been put together! Large quantities of water sloshing around the insides of the a/c will exacerbate uncontrolled instability, eventually leading to a top heavy a/c 'tipping' over.
2. If the rotors are still turning (quickly), they will strike the swell in anything >SS3. This could result in tipping the cab over or serious structural damage (not a problem if you intend to scrap the airframe after).
3. Water ingress will very very quickly affect the electrics. The most obvious problem being unable to communicate with the passengers/crew. This is by far the most serious issue especially when/if the cab turns over!
4. If the flot bags don't deploy evenly, the cab will sit skewed off to the swell / sit at an awkward angle and further exacerbate the eventual overturn.
5. If the drogue shute isnt deployed, the a/c will sit side onto the swell and within minutes, she will turn over in anything >SS4/5.
6. The worst I've heard of is SS6 and the a/c remained upright and pointing in the right direction for long enough to be recovered. The swell though was a long one and not too choppy.
The worst thing is thinking about all those people down the back while you are doing everything in your power to keep the ***er from tipping over! If she goes....God help the pax! At least you've got jettisonable doors and STASS and HUET training and correct gear and radio and ELT and and and.....
Don't go there.
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CF Sea King Pilot
Well, if you say that no other CF Sea King pilot has jumped in, that saves me reading all the posts. I just read the first page and this last page.
We did receive good training on putting the bird in the water and also taking off from the water. In most cases of ditchings, the reason that put you down there, meant you were going to stay on the water. However, I can recall that one crew did have a ditching and then a take-off sequence but after all these years, I can't remember what caused them to go in. However, they managed to take off and fly to shore.
The Sea King is great for taking off and landing on water - at relatively low sea states. But in most North Atlantic sea states, once you were in the water, if at least one engine could keep the rotor still turning, you might have some chance of keeping it upright in low enough sea states and if you still had enough outside visual reference (depending on day/night wx) to know which way was up. I remember a lot of our missions being at night and in higher sea states. Even with the rotor turning and flying rpm, the Sea King had a limited range of off-level before it was beyond the range at which it could be levelled, even at full power.
If both engines quit or were shut down, all bets were off. Being so top heavy meant it was likely to turn turtle pretty quick. But even then, the combination of the airframe float design and the inflatable bags would keep it floating for some time - in some cases hours, and in some cases a couple of days before slow leaks took their effect.
I was never more greatful than when I was given the privilege of taking the Underwater Egress training or whatever that course was called. It included being strapped in a fuselage, turning turtle and escaping, first in daylight, then blindfolded (night), then finding doors jammed requiring alternate exit, then having to work back into the cabin and removing an immobile patient out the door before exiting yourself. And it was good clean fun!
Another posting to follow . . .
Shipborne ops were conducted on rough water. The hauldown system locked the aircraft on the deck. That meant that you could handle ship motion up to something like nine or ten degrees of pitch and up to 31 degrees of roll while locked in. The landing gear wheel on the "upside" of a high roll would actually come off the deck but the hauldown probe in the belly had you securely locked into the beartrap so the bird could not roll right off the ship's deck. It didn't feel too comfortable though.
You would only experience that until the ship took a steadier course in preparation for engine and rotor start-up. Then the pitch and roll had to be quite a bit less - I can't remember the numbers now. There has been some discussion about blade movement, precession and all that. In practical terms, we had to do a rapid rotor engagement and the same for braking the rotor on shutdown. We would start one engine while it remained disengaged from the rotor. When aircraft and systems checks were done, we started the second engine and ran up the rotor together. The Sea King had droop stops to prevent the blades from drooping too low when at low rpm, until the rpm could be increased to normal. One of the things the deck crew had to watch for when we disengaged the rotor was to see if all the droop stops were working. If not, we had to quickly wind the rotor up again and try another disengagement.
There was a posting that mentioned floats were only used on smaller helicopters.
The CF used floats on Twin Hueys (Bell 212). They were huge ungainly looking things - big, black, long cigar shaped, inflated bladder type floats, with the bows tapered upwards.
They also used similar looking things on the Kiowa (Jet Ranger). If the situation required start-up/shut-down on the water, you had to paddle away from shore so that you could spin around doing a 360 until the tail rotor became effective. In flight you had to anticipate slowing your roll rate in a turn because of the weight and momentum created by the floats being heavy and at a distance from the longitudinal centre line of the aircraft. On shut down it would turn as well when the rotor lost effectiveness.
We did receive good training on putting the bird in the water and also taking off from the water. In most cases of ditchings, the reason that put you down there, meant you were going to stay on the water. However, I can recall that one crew did have a ditching and then a take-off sequence but after all these years, I can't remember what caused them to go in. However, they managed to take off and fly to shore.
The Sea King is great for taking off and landing on water - at relatively low sea states. But in most North Atlantic sea states, once you were in the water, if at least one engine could keep the rotor still turning, you might have some chance of keeping it upright in low enough sea states and if you still had enough outside visual reference (depending on day/night wx) to know which way was up. I remember a lot of our missions being at night and in higher sea states. Even with the rotor turning and flying rpm, the Sea King had a limited range of off-level before it was beyond the range at which it could be levelled, even at full power.
If both engines quit or were shut down, all bets were off. Being so top heavy meant it was likely to turn turtle pretty quick. But even then, the combination of the airframe float design and the inflatable bags would keep it floating for some time - in some cases hours, and in some cases a couple of days before slow leaks took their effect.
I was never more greatful than when I was given the privilege of taking the Underwater Egress training or whatever that course was called. It included being strapped in a fuselage, turning turtle and escaping, first in daylight, then blindfolded (night), then finding doors jammed requiring alternate exit, then having to work back into the cabin and removing an immobile patient out the door before exiting yourself. And it was good clean fun!
Another posting to follow . . .
Shipborne ops were conducted on rough water. The hauldown system locked the aircraft on the deck. That meant that you could handle ship motion up to something like nine or ten degrees of pitch and up to 31 degrees of roll while locked in. The landing gear wheel on the "upside" of a high roll would actually come off the deck but the hauldown probe in the belly had you securely locked into the beartrap so the bird could not roll right off the ship's deck. It didn't feel too comfortable though.
You would only experience that until the ship took a steadier course in preparation for engine and rotor start-up. Then the pitch and roll had to be quite a bit less - I can't remember the numbers now. There has been some discussion about blade movement, precession and all that. In practical terms, we had to do a rapid rotor engagement and the same for braking the rotor on shutdown. We would start one engine while it remained disengaged from the rotor. When aircraft and systems checks were done, we started the second engine and ran up the rotor together. The Sea King had droop stops to prevent the blades from drooping too low when at low rpm, until the rpm could be increased to normal. One of the things the deck crew had to watch for when we disengaged the rotor was to see if all the droop stops were working. If not, we had to quickly wind the rotor up again and try another disengagement.
There was a posting that mentioned floats were only used on smaller helicopters.
The CF used floats on Twin Hueys (Bell 212). They were huge ungainly looking things - big, black, long cigar shaped, inflated bladder type floats, with the bows tapered upwards.
They also used similar looking things on the Kiowa (Jet Ranger). If the situation required start-up/shut-down on the water, you had to paddle away from shore so that you could spin around doing a 360 until the tail rotor became effective. In flight you had to anticipate slowing your roll rate in a turn because of the weight and momentum created by the floats being heavy and at a distance from the longitudinal centre line of the aircraft. On shut down it would turn as well when the rotor lost effectiveness.
I don't want to be the best pilot in the world - Just the oldest
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Ditching statistics
G'day all,
Can anyone point me in the direction where I can get some up to date statistics on ditchings involving RW aircraft in the oil and gas industry.
We have some info that we give in our HUET courses but I have some doubts as to its accuracy given that the information only applied to ops in GOM and North Sea and is now quite dated.
Thanks
IJ
Can anyone point me in the direction where I can get some up to date statistics on ditchings involving RW aircraft in the oil and gas industry.
We have some info that we give in our HUET courses but I have some doubts as to its accuracy given that the information only applied to ops in GOM and North Sea and is now quite dated.
Thanks
IJ