Water Ditching
 

Opinions please on the best (better/safer) options in which direction to rolling over a helicopter after an emergency water auto landing please? I have been told roll her over to the right in an anti-clockwise machine so that the reaction from the blades impacting the water sends the tranny & engine backwards away from you. Others have said attempt to settle her in flat so all blades contact water at the same time? Thoughts, comments, experience on this topic gratefully appreciated. Cheers

I dunno but methinks that once you hit the water you're along for the ride. The helicopter is likely going to roll one way or another; just roll with it. Resistance is futile... What are you doing over water without floats anyway?

As long as you have RRPM it's not "futile."

Yes, rolling to the right is wise in a two bladed machine.

Lots of people work over stretches of water without floats.....


RH

Rolling in any direction is an old wive's tale, discredited by the flight manuals and military procedures for several years now, but awfully hard to wipe from public memory.

If you have to ditch, open the doors prior to touchdown if you can, enter the water nicely, and let the aircraft settle straight down, holding it upright with cyclic as long as you can.

The greatest danger in ditching is drowning, and doing a roll at entry is a fine way to invert the aircraft, get lost trying to find the exit and drowning.

Ditching..
 

We were always taught that if it was a controlled ditching, to try and land on the crest of any waves (if there was a significant sea state) and NOT to use the rotor brake while shutting down :uhoh:
Oh yeh, and keep yer head down till the blades have stopped :ok:

I agree with Nick.

Planning ahead is the most important safety consideration (training, utility or emergency floats, personal flotation devices, and a plan).

Part of the emergency plan should be to open a door or window during the descent so that an expeditious exit can be performed.

As anyone who has experienced a dunk tank will attest, exiting the aircraft while upright is far less difficult than when it has rolled past the vertical to the inverted.

"Rolling in any direction is an old wive's tale, discredited by the flight manuals and military procedures for several years now, but awfully hard to wipe from public memory."

The Army still teaches rolling right to stack the broken blades over the tail and thus not impede exiting from the cabin. At HUET they preached rolling and not riding it straight down, as the helicopter will roll eventually and better to get it rolling and done while still early in the crash sequence -- the dunker machine is set up to roll immediately when it contacts the water to teach such a little event.

Plus the Robby POH says roll left, no clue why left but it says roll.

Personally, I don't care what kind of top gun maneuver the pilot pulls after hitting the water, and I doubt it makes too much of a difference what he does, but it still is actively being preached! I still believe that doing a good auto to 20 feet and pulling the crud out of the collective while leaping from the cockpit is the most appealing option in my eyes... no need to escape a twisted wreck; it's just like doing a dive off the high jump with a fat kid rolling in with a cannonball on top of you.

Mike

If you have done an auto to the water in a single, you probably won't have enough Nr left to give you much cyclic control and since most helicopters are top-heavy, they will invert as they sink regardless of which way you try to put them in. Know your escape exit and get one hand on there as soon after impact as possible to help orientate yourself for the escape.

Back in the olden days... we were taught if you had a controlled ditch, get everybody else out in the hover and then the expensive nut holding the cyclic would head downwind/current and put the thing in the water, pull throttles or twist the twist grip or shut off the main steam valve or whatever your particular machine required.
Jumping out from an auto at 20'? Sounds like something the Pink Panther (cartoon) would do. Just before the plane smacks the ground... jump up! I mean, it can't hurt to try, right? That sounds like an excellent way to die to me. A 20' uncontrolled fall into water WILL hurt... and a few thousand pounds of alloy and composite whirling in on top of one will hurt a bit more.
Rolling over? If one has floats... maybe it WON'T roll over (immediately, I mean). In that case, why make it worse by deliberately rolling it? Also, what if it's one of those Grenouille machines... then all that rolling right jazz doesn't work, anyway.
I can't speak for anyone else's skills, but I'm dubious of my own ability to will a helicopter to remain stable with decaying RRPM at 20' while I unstrap, swing myself around the various levers and so on to make good my escape (don't forget to unplug the helmet/headset!). Best place to be during rotor blade impact is generally under the hub, more or less... all the bits fly away from one, at least that's what the books sort of say... never tried it myself, you understand.
Take HUET seriously... don't whine when you get water in your sinuses during training...
Nothing personal... but my observations have been that what US Army Aviation as an official organization knows about flying over and around water wouldn't fill a thimble (there are plenty of individuals who are exceptions to that). Used to escort a bunch of Army folks inter-island because they wouldn't fly over open ocean on their own... like herding along little olive-colored ducklings t'was... (kept their t*sticles in a little mason jar with a flotation collar for 'em... safekeeping you understand... returned them to 'em when they got to Bradshaw)

"(kept their t*sticles in a little mason jar with a flotation collar for 'em... safekeeping you understand... returned them to 'em when they got to Bradshaw)"

Funny you say that... current policy out in Hawaii is no single ship VFR interisland flight. IFR for single aircraft only. Ridiculous. Had a chopper have an gyro break on the way to Maui, they launched two ships VFR to escort the one chopper back on a clear blue day.

The singles (58s) have a harder time... nothing allowed to the other islands unless you are going to Bradshaw for a field exercise. Risk aversion at its finest.

That's just plain silly. Ah, an IFR flight plan will put you on an even altitude... that increases your risk of being found in the Molokai Channel a thousand-fold... I see the logic now. Never mind that you can go FSS and tower-to-tower pretty much all through the Hawaiian chain, or at least it used to be you could.
Like I say... put Army Aviation decision-makers over water, watch their brains dissolve... it's a phenomenon that has been observed independently by many people of my acquaintance. They are like Southern drivers in snow flurries... they just lose their minds.
So, could they have launched one IFR to get the broken one and then they could return VFR? Or was the gyro-free one not considered to be in flyable condition?

I agree

I have seen a machine where a M/R strike on the retreating blade (ground strike) put a dent in the pilots head from the xmon severe enough to put him out of flying forever. (the pilot had a helmet on, but to no avail)

I am surprised at Nick's statement.

In Mechanics every action has an equal and opposite reaction.

When hitting the ground , or the water, think;
1. Do you have lots of energy on the M/R system? How can I use that to my advantage, (if it is necessary) especially to dissipate damaging velocity?

2 Answer. After disspating the downward velocity, (only if into water) then roll the advancing blade into the oncoming obstacle.

3. The items which it is connected to, I.E. the xmon must tear backward away from the cabin occupants. Have seen that many times.

Above all, THINK. Energy is stored in the rotor sytem while it is rotating.

Think about how you can use it to help yourself.

Water strikes tear airframes apart like you wouldn't believe.

Tearing of airframes is better to be used for time (and energy disspation) to get out from under water.
tet

Hawaii: Don't want to hijack the thread, but...
 

I never knew that about Hawaii. I used to fly off the chart in the GOM in a medium, and about 150 miles off the beach VFR in a 206L (3 years ago).

Why would they place such an odd restriction on inter-island flights? :confused:

Ditching..
 

SilsoeSid,

That's the funniest thread reply I've ever read on prune, I am going to nominate you for a comedy award at the oscars :E

Roll it away from your side so you put the other pilot under water!!
Seriously there was a lot of vision years ago of Vietnamese pilots fleeing Saigon to US warships at sea. These "controlled" ditchings by pilots with questionable skills showed that the water entry was relatively benign and survivable. A night "autorotative" entry from "jump" height possibly downwind is altogether a different story. I have friends who have done this and most would say they put in control inputs almost by numbers on the gauges and found themselves on the surface. The RAN had lost no-one in a ditching from 1948 until around the 1980's when two backseat crew died as a result of an upside down uncontrolled ditching from around 40-50 feet at 30kias or so when a main rotor gearbox gear exploded and took out one of the Wessex's primary jacks.
Take HUET seriously, know your primary/secondary escape routes and always consider the possibility of a controlled/uncontrolled diching - have a plan.
GAGS
E86

Topend, you are correct ref the advancing blades striking the water (Or anything) will tend to push the transmission back. 2, 3. 4 5 or whatever the amount of blades will not matter.

"Never mind that you can go FSS and tower-to-tower pretty much all through the Hawaiian chain, or at least it used to be you could."

It's still used for multi-ship VFR flights. But regardless, HCF does great VFR flight following across the whole chain. Seamless. Nobody uses IRS anymore except military chums. And the logic was that if you were alone and had a problem, being IFR would make the rescue come much quicker :confused:

I fly inter-island in the pistons outside of work and all the coworkers think I'm absolutely nuts.

Anyone who does even a bit of overwater flight should do HUET. One of the most eye-opening experiences I've ever done. Also, the HEEDS bottle is the best thing since franks and beans... even in training, having that puppy on you reduces the fear and stress of going in 10 fold. You can buy a small "spare air" tank that Scuba divers carry for a hundred dollars and never worry again about getting snagged and running out of air, or having to leave an unconcious/trapped person in the sinking wreck because you need to surface to breathe.

Mike

What not to do?
 

Or if its your last resort?:


http://www.youtube.com/watch?v=bV7ccOdonCo

Couple of crazy jumps out! Sad to see the Hueys dying that way....

H-M x 2 - If you have, as you say you have, done some HUET training you will know that this comment is crass and possibly dangerously misleading - particularly to others who may take your words literally and go purchase such a device without training.

The SOLE purpose of HEEDS is to assist yourself to escape from a ditched machine. Having it with you significantly increases your chance of survival should you be or become snagged during your initial attempt to escape but to state that you never worry again about running out of air is wrong. There is no question that in such an unfortunate event the shock and possibly also cold shock effects will cause you to hyper-ventilate and that little bottle of air wiill not last long.

Not to mention a number of other gotchas that will catch someone out using such equipment without training.

However more importantly it should never be viewed as a means of assisting an unconscious or trapped person in a sinking wreck. Yes of course we would all like to be considered hereos who will save the day and all the passengers with our acts of selfless bravery but going back into a sinking aircraft with a small spare air supply will undoubtedly add an extra name to the casualty list - yours :(

Some legit statements... I know I won't be able to stay down forever, but that little safety net the bottle provides makes me feel assured that what I've got in my lungs when I go down is not all that I'm going to have. Lowers the stress and reduces the chances of freaking out... hearing stories of others that have done the real dunker ride without any training or equipment, and how they all managed to calm down and work their way out rationally, makes me think that the bottle helps people get out period, not just gives them more time. Put air in a scared crashed pilot's lungs and I gaurentee you that the lowered fear and increased confidence they get will help him/her out quicker... not to mention give them some more air. And the bends or a possible air embolism vs. never getting out is an easy decision, at least in my mind... it's like sending someone to a gunfight without a gun because he never learned to shoot it. I think you've got a better chance with the thing, even if it's not ideal.

The instructors also stated the bottle helps you to get out, but after seeing what the bottle that I carry can do, I know I've got enough time to spend a second or two helping someone else out, or (more likely) swimming to the engine compartment to see why the damn hunk of !!!!! let me down. Even if you can't go to the class, I say get the best equipment you can afford/find/figure out how to use, get familiar with it's capabilities, and use it to it's most when the unfortunate arises...

Mike

The question should not be which way you roll a helicopter after a power off landing to water; but why you would be flying a civil helicopter over water, beyond autorotative glide distance to land, without floats?

In the case where the helicopter lands in the water after hitting a tail rotor on the edge of a heli-deck or hitting a main rotor against the mast of the ship, or LTE on approach, or due to spatial disorientation, the chances or rolling to one direction or another are rather slim.

With properly deployed emergency floats or fixed utility floats there should be no reason an upright landing cannot be made power-on or power-off.

Well Rich Lee have you not ever done circuits/patterns, or an approach over water to a pad/airport which is perfectly legal & regularly done? Or what if the floats fail to deploy, or if your doing aerial work or private ops over water which you do NOT require floats? Or your within auto distance to land but the beach is packed with people, or for some other reason not suitable? So there are plenty of legit what ifs over water? The question is what if the noise stops during over water flight & you HAVE to ditch in the drink; then what are the options & alternatives? Based on some great valid responses here, then given a ditching in a anti-clockwise rotating machine the safer option is after the flare level cushion... settle in, then roll the machine to the RIGHT, hence reducing the chance of the tranny & engine joining you in the cockpit for a little tea & crumpet. Thanks heaps for the constructive responses. Cheers

I was told by some bloke who ditched a 206 into sydney harbour, right between the headlands and too far from each, that if you roll the advancing blade (I think) into the water, the resulting massive torque back through the system will spit the gearbox out backwards away from the cockpit.

Well he said it worked anyway. I'm sure someone knows the full story.

I did the 'waterbird' course on the US Sea King- great aircraft to take off again from water if you've got 1 engine left. The ditching at 30kts fwd speed was fun also:ooh: with the aircraft coming to a stop in about a length and a half!!

Great tale OP!

And a classic "handle" if I judge your line of work correctly.


Best.

Sicknote:ok:

PS

Off to start a similar thread on the GA boards.

It's all a pretty silly exercise, really. Why on earth would anyone intentionally ditch a helicopter under power? Perhaps you can, but I cannot think of a reason...any reason.

If you think about it a little (and those Vietnamese pilots surely did not but we can forgive them if they were so, um, preoccupied with other things to wonder, "Now how would Nick Lappos do this?"), you absolutely do not want to have power to the rotor if it's going to contact anything. Thus, engine-OFF for water ditching.

Once you take the torque away from the main rotor and slow it as much as possible with pitch, it really won't matter which way the helicopter rolls. I know of a certain ship with a two-blade system that rolled over after landing on uneven ground. As it was going over, the pilot managed to get the engine off so the rotor was no longer driven. The transmission stayed put. The blades were trashed but after inspection, the hub, grips and drag links are flying on another ship to this day...somewhat unbelievably to me but there you go.

Perhaps ditching theory was important in the UH-1, with that long mast and that big, tall transmission. (Ever look at/think about that? Yikes! What a poor design.) But in other helicopters with better trans mount designs, it just doesn't matter. If it's a controlled ditching, get the ship down onto the water level and then, keeping it that way, pull the pole up as high as it'll go to slow the MR. Let it roll and don't worry about it. That trans ain't going anywhere.

But let's not kid ourselves into thinking that there would ever be an occurrence where it would be necessary to ditch a helicopter in the water while it's still under power, okay?

FH1100

Ok, ask the guys who had a internal fire caused by a 3000psi utility hydraulic leak, VERY large fireball inside the aircraft, ditched it, rolled it over putting the fire out and all the crew got out. The Jaguar pilot who had ejected that they were about to rescue got a bit of a shock when the rescue aircraft needed rescuing however.

Also- any impending catastrophic gearbox oil problem over water away from land- offshore ops anyone?? I can think of at least two RN ditchings caused by this.Granted all happened with older aircraft- ok, Seakings, but not outside the realms of possibility even with newer offshore aircraft with cabin fires etc. I would rather use the big wet fire extinguisher than get crisped airborne....:uhoh:

O-P - ISTR in that particular instance the aircraft was rolled to the right because the handling pilot was in the left seat and he wanted his boss in the right seat to get wet first! :E

I also seem to recall the handling pilot was well looked after by the nurses when he got to hospital....but thats a story for another time ;)

Not that it matters but just for accuracy the jag pilot had actually been rescued some time before. The seaking crew had been tasked to locate the wreckage on the seabed using their sonar.

Yes I have. In my younger days I even used to ferry long distances across water in a single engine helicopter without emergency or fixed floats. That doesn't make it right. Now I would probably insist on floats if I needed to fly over water in a single engine helicopter.

Good question. Of course that begs all the other questions like what do you do if the hydraulics fail, or if the controls become stuck, or if the pilot panics, or electrical system fails and the battery is dead and that causes all the electronic displays to fail, or you are in a sea state that cause your blades to hit the water before you land, or you can't align properly with the swells? All perfectly legitimate questions alone or in conjunction with each other. Secondary and subsequent failures of multiple systems do occur, but I would still rather have properly serviced floats as opposed to none when flying over water.

The bottom line is you do what you can do get the aircraft into the water at a vertical descent rate and horizontal speed that allows the best survival opportunities. I am a believer in following manufacturers recommended procedures. If you are in an aircraft with a transmission that wanders about when the blades strike something, and a manufacturer like Bell says to roll the helicopter a certain way, then do what Bell tells you to do. You can't be faulted for doing what the manual tells you to do.

There are plenty of legal operations that fly over water without floats. However, do something within legal boundaries doesn't mean one is always exercising the best possible judgment. Imagine the case of a pilot carrying passengers over water and the engine or engines fail. Imagine the pilot did all the right things but the passengers drowned, what would the pilot's justification to their families be .... 'it was legit'? Please do not get me wrong. I am have been involved in operations that were perfectly legal and standard operating procedure only to realize years later that there were safer ways to do things. I have learned that there is a safer way to fly over water and that is to do so with floats. With or without floats, every passenger should be briefed on how to exit in a water landing, and how to use personal flotation devices; and they should be wearing those personal flotation devices.

If I made a decision to accept the risk of flying over water in an aircraft without floats, I know that in the event of an engine failure, I will fly the aircraft all the way to the water, and on the way down I will make sure I have a door open. I will use full collective on water entry to dissipate as much main and tail rotor energy as possible. If at that point I have enough control power in the main rotor to roll the helicopter, I might make the attempt if that is what the manufacturer recommends, but I really wouldn't expect too much from the rotor at that point.

Fire, main gearbox oil loss, serious vibration. Just a couple of reasons why one would "fly" a serviceable helo into the water under power, I would suggest.

Provided the pilot still had control of the aircraft after landing (Sea state <3) then he might have the option to shut down before the blades make contact with the swell and decide for themselves which blade impacts first (adv / retr).

The gearbox would disconnect and depart the airframe in the opposite direction and there have been numerous incidents which reflect this.

The bottom line is to alight on the surface of the water with minimum force, inflate the flot bags, slow the rotors gently and depart the aircraft.

Twin Huey Man - speaking as one of the most current HUET qualified pilots in NATO (I did my requal this morning) your chances of 'swimming around' and helping someone else are somewhere between none and F-all. You can see almost nothing in a benign environment like a swimming pool without goggles or a mask and you would see even less in the sea, and that's in good light. The bottle is there as a secondary escape system should you fail to get out quickly - not to make you Marine-Boy/Navy Diver/Hero of the day.

The bottle should give confidence to dispel fear, not breed over-confidence.

To chime in with "oldpinger" the transmission scenario is one of the prevalent reasons you would ditch with power with the notion that the impending failure (indicated by chip light with perhaps torque spikes, yaw kicks, the sound of marbles in the transmission) means you will probably lose the ability to generate lift altogether very soon. The warnings I have seen state that entering into an autorotation with an impending transmission failure may cause the transmission to seize earlier than if you maintained power input from the engine (mainly at the point you are pulling to cushion and the turns begin to bleed off). Another possibility is folks who get offshore and become disoriented and then run themselves out of gas or get caught in weather that runs them out of gas (MH60 crew flying in "The Perfect Storm"...quite the story if you aren't familiar- night time ditch into 75' waves- good times there). Knowing it was a matter of time, I would look to get rid of my pax in an air taxi, get all set up with doors gone, floats blown (in that order),and perhaps target the crest of a wave. I would rather have the opportunity to land in the water on my terms vice trying to see how well I could auto to a particular sea state.
As far as which way to roll, I think the sea will decide that for you, but I am happy to listen to any test pilot who has the answers from experience...the three pilots I have met who have ditched power on stated it wasn't a prevalent thought at the time.

That EMS EC135 that crashed the other night (http://www.pprune.org/forums/showthread.php?t=329188) got me thinking about this thread and the theory of the gearbox departing the airframe in the oposite direction of rotorblade impact...

How come that the gearbox on that EC135 (it rolled over after clipping a trailer on (forced) landing) moved a mere 5 inches towards the side of impact?!?
Last time I checked dirt is a lot harder than water - or was the crew just lucky not beeing beheaded by a flying gearbox? (pardon my sarkasm).

"Twin Huey Man - speaking as one of the most current HUET qualified pilots in NATO (I did my requal this morning) your chances of 'swimming around' and helping someone else are somewhere between none and F-all. You can see almost nothing in a benign environment like a swimming pool without goggles or a mask and you would see even less in the sea, and that's in good light. The bottle is there as a secondary escape system should you fail to get out quickly - not to make you Marine-Boy/Navy Diver/Hero of the day.

The bottle should give confidence to dispel fear, not breed over-confidence."

Congrads on your trip to the dunker. Always a fun day when we go.

I understand what a lot of the instructors say, and why they say it, and by all means I don't think one guy on a bottle will save an entire bus load of scared people, but when you've got that much of a safety net, it's not worth it to me to not at least give a look to make sure my buddy is getting out. When we do our briefs before flying overwater, the two crew on each side of the aircraft are told to "make your best effort" to make sure your co-aircraft-sider is getting out, and if we have passengers, we're to do the same for them. We did so in the dunker, hell our instructors would breathe the same heeds bottles we did!

Also, I'm think one of the bigger HUET companies has classes for HEMS guys that fly overwater, and they train to extract a patient during the ride.

As for the visibility, I know it can be pretty bad at times, but I'm also a guy who cruises down to 100 feet on the weekend and I've never had a problem seeing at least a bit in front of me at those depths on a murky day doing mask drills. I've also been caught on the most innocent of things down there, unable to free myself, without 2 seconds of help from my buddy. We have loads of crap hanging all over in the back of our aircraft, plenty of stuff to get hung up on, and the simple help of someone who is already out, with a good view of the problem, and the calmness that comes from getting out may be all the help someone needs to make it through.

By the way, I'm not arguing that everyone should have the same attitude, but the thought that people should be allowed have a heeds bottle without expensive, sometimes hard to find training, and that it is capable of only very limited things, is a pretty pessimistic view on things.

Mike

TwinHuey - I cannot see how anyone is going to have a good view of any problem underwater without a mask - if you are caught up inside and they are outside they will, at best, be able to see a blurred mess. If you are talking about a realtively controlled ditching where the aircraft has inverted but not sunk because the floats have inflated then there is possibly a case for trying to extricate others but the situation we train for is where the aircraft has inverted and is sinking - no-one should ever consider going back into that.

Unfortunately, letting people believe they can save others in this scenario is more likely to cost lives. BTW does your dunker training include night ditching?

I agree that "going back" is not the safe thing to do. Reaching across while still maintaining a reference point is more like it. We also brief that, if you end up on the surface, you don't go back down. On the way out, after having sorted yourself but still with the wreck, do your best to ensure your buddy made it out. I think it might be different in a larger airframe where you can't just reach out and grab your entire crew...

We didn't do night dunks, but we don't do much of any night over water work. Pretty frowned upon unless it's rather important. I think if the event happened at night, it would be a miracle of anyone made it out expediently let alone did buddy checks on the way out.

Mike

Phil77,

I am by no means a physicist but wouldn't the fact that dirt is much harder than water be a contributory factor?

When a blade hits the ground, isn't it more likely to shatter or break in some way? (See the photo of the Philly EC135 - all of the blades are sheared at the root.) This will dissipate most of the remaining kinetic energy.

However, when a blade hits the water, isn't it just as likely to decelerate rapidly? This means that a lot of the energy will be transferred along the blade until it gets to the end ie the gearbox.

Although saying that, maybe it comes down to the more modern design of the EC135? I remember from the video of that ENG AS350 which came down on a New York roof that the pax were very lucky not to get clobbered by the gearbox when it came away from the aircraft.

TwinHuey - unfortunately, we do spend a lot of time at night over the water so one run is conducted in half light and one in the dark - we do 6 runs altogether, 4 without STASS/HEEDs and 2 with.

On the 2 STASS runs we end up swimming inside the aircraft (Sea King size) to escape from an alternate exit (cabin door for example).

On the last run I had to get from the RHS to the air stairs door (about 5 feet in my 8 o'clock position) - sounds easy and I correctly orientated as we hit the water but, by the time I was upside down, had released my safety harness and was breathing on the STASS, I was completely lost and tried just about every exit on the aircraft until I finally found the one I was supposed to get out of. It was difficult and disorientating and that was in a swimming pool in daylight after 5 other runs and only in 4m of water.

In the real case you are very unlikely to be able to do anything other than just get yourself out - if your training lets you believe otherwise, your training isn't hard enough.

Don't forget that the rate of consumption of bottled air will be significantly greater in a real emergency than in the HUET: the application of extra adrenalin and cold water will see to that! It could easily half the endurance.

How long could you expect from these bottles of air?