Ditching a helicopter: (incl pictures)

[GLSNightPilot]

The usual thing in the Gulf of Mexico is for the autorotation to go fine, the helicopter floats with no damage, until the boat gets a line on it & pushes the throttles forward, whereupon the helicopter turns turtle. Max speed on the floats is probably < 5kts, closer to 1, but the boat captains are impatient with that speed, & almost always the helicopter ends up upside down, with the blades spinning, then cutting the tailboom. I saw one B206 that had just had an engine decel just after takeoff, the pilot put it in the water with absolutely no damage, and by the time it was back on the platform helideck the blades were about 3' long, it had no tailboom & no skids, & was a total wreck. The CG is very high, & the helicopter will roll in a heartbeat. I can't imagine one sinking upright, since the CG will be much closer to the head even with the fuselage filled with water, but I guess anything is possible. I certainly wouldn't want to bet my life on its sinking right-side-up.

[Oracle]

Ditchings

A quick summary of comments:

1) Wessex types were notorious for losing float bags on anything other than a flat entry at low speed. We lost a Wx5 off Norway at night and although the bags inflated as advertised, the force of the impact (Inadvertant Flight into Water at high speed at night) tore one off and the other soon deflated - it sank like a brick, both crew lost, sadly. If the ditching it controlled and level (in good/moderate sea conditions) the Wx would sit fat, dumb and happy as long as you didn't do anything daft like engage the rotor brake, which oftens turns the higher c.g. aircraft turtle - not recommended practice - let the blades coast to a standstill or hit the water - it's always safer and I have even know crew members who jumped out before a controlled ditching (UH1) to then get back in again afterwards once the blades started to trim their hair some on the surface! There were several Wx recovered successfully/undamaged after controlled ditchings.

2) BELLs tend to ditch nicely if well controlled on entry and as long as the floats aren't manually deployed in flight beforehand. This is because many of the flot bags (skid mounted) have lengths of plastic inside to stop the bags from adhering to themselves in the heat etc. The AB205/UH1 thus would dump 6 to 8 feet of plastic sheeting into your tail rotor during final autorotation (unless your timing was immaculate!). The 412 is better and has been recovered successfully several times after controlled ditchings. The only failures being when rescue craft have subsequently puntured the floats by 'coming alongside' under the stationary rotor disc thinking that the floats are bloody fenders! Best to get everyone over the side into as many liferafts as you have as quickly as possible, and then be recovered from the liferafts - saves the aircraft in many cases and stops people sitting in the ditched machine waiting for the inevitable to happen!
3) The S76 floats well and has great float gear - as demonstrated by many. It will also block the pilot's door from opening however and is most effective at stopping the aircraft if inflated (accidentally) during ground taxy! More difficult to puncture than the Bell/Wx, the spread and size of these puppies will normally keep everyone's feet dry! (As opposed to the wasp/scout with it's flotation level 1 feet below the surface!).
4) Blackhawk. This Beast is a 22,000lb lead sinker - so unless you have flot gear fitted (which few have), don't expect it to keep you on the surface in the event of a ditching. The ESSS stubs and tanks would likely detach anyway (they're only only Glass-fibre) and would probably just ensure a nice level glide down to the sea-bed! I would recommend underwater escape bottles as a standard (as in the USN) for any pilots flying the Beast offshore!

So - recommendations are, in a controlled ditching, let the floats work automatically if they do so, or operate at the last minute otherwise, don't use the rotor brake at all, get into the liferafts IMMEDIATELY and remain attached to the aircraft (if still afloat, that is!) until rescue arrives. Then keep the rescue tug/boat aways from the flotation gear - so that you get a bonus for saving the aircraft for salvage! ALERT DISASTER CONTROL run a very good HUET course in Singapore and might help with any queries.

[Arm out the window]

Pop-out floats

I'd be interested to hear of people's experiences of having to use pop-out floats in anger.
I'm now flying B206's fitted with these, and would like to see what other users reckon about things like:
- the best time to activate them in an auto
- how the aircraft flies during and after activation
- what they're like when you hit the water
- any other observations or thoughts on the matter.

I've operated with fixed floats a few times in a 205, and remember being particularly surprised at the huge shove of forward cyclic that was required on auto entry to stop the pitch-up. Obviously that wouldn't be needed with pop-out floats if you activated them in the latter stages of the flare, but what other things might come in to play?

[Nigel Osborn]

Pop outs

I haven't popped a 206 float in the air, only once in a As350, but I have done a few circuits with the floats blown up and it felt very similar to fixed floats. i.e. no problem. The As350 flew normally, so basically it made little difference.
The tendancy is to blow the floats too low. Obviously if you can hover, then blow them in the hover. However general practice if in auto is to blow them early, by 350 to 500 ft or so, then you have plenty of time to get the machine sorted out so that you can concentrate on the landing.

[spinningwings]

Very good question...and no doubt lots of semi correct answers (including mine)...in my view be aware of the A/C gross wt at the time of needing them....there is considerable disturbance to the airflow thru the rotor with floats "popped" in autorotation...such that 206s on fixed floats require considerable autorotation RPM re rigging when fixed floats are installed/removed.

Thus were I in the A/C and it were heavy I might 'pop' the ******s a good bit earlier than if the A/C were light because the weight of the A/C would put the auto rpm at the higher end of the green...with the A/C at lighter weights (solo) the auto rpm would be at the lower end and any disturbance to the airflow in my opinion would be undesireable ....... having said that we assume that both sides WILL appear at the same time on command (???) a plan to consider might be to pop them after flaring to zero/zero the A/c above the water and then let it settle in the water hopefully upright hoping the pax if there are any don't rupture them opening the flaming doors.... good luck talk to your Chief Pilot ...cheers

[chopperdr]

Sirs: regarding float inflation, would suggest that the floats be popped below float vne, the emergency float systems i have installed and worked on certification testing would normally be popped well before the flair, usually around the 1000ft mark, this allows the floats to inflate and settle, then the pilot can concentrate on a smooth auto. as for a/c weight, the floats are designed to provide floatation on max gross a/c, one should also check if the floats are certified as ditching or emergency floats, there is difference.if you wish there is very good promo video available from apical industries showing real full on autos of many different helicopters, let me know if you would like one and i will pass your info onto apical.

[widgeon]

and gentleman Jim is the pilot on many of the videos , i think Andreas filmed the 105 ones.

[Arm out the window]

Thanks for your informative replies.
The video you mention sounds like it would be well worthwhile getting hold of, chopperdr.
I'll ask around at work and see if anyone has a copy; if not, I would be keen to get hold of one myself.

[Run-on Landing]

Inversion after Ditching

I seem to remember watching a TV programme (Tomorrow's World on BBC, I think) a good few years ago that featured devices in development to prevent helicopters capsizing completely after ditching, but haven't heard anything since.

I had a look on the internet and found the following web site and also found out that the CAA had conducted trials in 2001 into escaping from a side-floating HUET.

http://www.bmtfm.com/devices_to_prev...icopter_to.htm

Anyone heard/know any more? Comments? Opinions?

[[email protected]]

Interesting - but will the extra weight/drag and its effects on the C of G both longitudinally and vertically on the aircraft be acceptable.

I think you would have to vastly increase the thickness of the engine bay doors to provide sufficient buoyancy to stop the aircraft rolling over.

The area around the engines is subject to high temperatures which will have to be taken into account - also if the blades make water contact at significant RPM during the ditching, they will probably tear the transmission and possibly the engines off anyway.

If someone makes it law it will happen - if not then don't hold your breath (no I mean do hold your breath cos you'll be upside down)

[zalt]

I hear that the side floating option came out well in the HUET trials (as the water pushed people up to the windows) compared to up-right submerged and inverted..

Talk of a design study on the mods required for a in-service aircraft.

[GLSNightPilot]

Even if you put flotation in the doors, or even around the engines, I'm not sure it would prevent the aircraft from rolling over. The vertical CG is so high, I think it might roll on over, especially if the seas are up. That's why dynamic rollover is something to be considered in a helicopter - the CG is way up there, & it's relatively easy to get it outside the skids, or wheels.

[NickLappos]

I always find it interesting how the safety garus can sometimes look into the wrong end of the telescope. I recall the droll Boy Scout rule for packing eggs - pack eggs at the bottom so when they break, they don't get eveything wet!

Nothing can be nothing more depressing than making aircraft safer by making them float better when a critical failure occurs. It is even more depressing when the normal flotation system is expected to fail and let the aircraft capsize! So we enhance safety by putting a second flotation system on the aircraft!

OK enough sarcasm. How about we just require the normal floats to keep the aircraft upright? How about we require the design to have enough redundancy to assure that ditching was a very remote probability?

[GLSNightPilot]

Nick, I have to agree with you. To me, the flotation is just to give me time to get out of the helicopter. Once I'm out, I'm still not happy - I've seen sharks the size of my helicopter swimming around out there, & everything in the water can swim better than I can. I'd far prefer something that kept me safe and dry so I didn't even have to think about floats.

But what is the cost? You can design in so much redundancy that the aircraft isn't economically viable, and no one can afford it. Consider that the vast majority of the aircraft operating in the US GOM are single-engine, the C+ costs us more to operate than a 214ST, and the S92 is likely to be so expensive I'll be surprised if 10 ever operate here. Somehow, the costs have to come down and the oil companies have to be convinced to spend some of the exhorbitant profits they're making. In the meantime we're hanging our a$$e$ out, and nobody seems to care.

[James Roc]

Ditching a single engine Heli

I've heard conflicting opinions on the best and most safest way of ditching a Heli in the sea and surviving following an engine failure and would like your opinions on the matter. Is it best to back cyclic and use the tail rotor to slow the rotors down or sideward movement and let the main rotor hit the water first?

[flyer43]

By far the best idea is to have two engines. The chances of ditching are dramatically reduced!! Altrernatively, you should avoid flying single engine machines over water.................

[B Sousa]

Unfortunatley Flyer thats not an option for some. I have often pondered my little Bell Baby getting quiet after many hours of overwater between Florida and St Thomas. The water gets a bit deep there, but warmer than up near UK Land.
As to ditching there are too many variables to think about to have one pat answer. Calm seas, vs. Rough seas, Engine failure vs, partial . One will just have to decide at the time based on whats available.
For sure its easier to utilize pop-outs and attempt to get the thing upright with blades stopped so you can exit and take all your toys with you.
That opens another bucket of worms as to what your going to have for survival, as the heli heads for the bottom..

[S76Heavy]

First, make sure that you have done a HUET course, so you have a chance of escaping when it goes belly up (not a question of IF but WHEN). Even with floats, they will buy you time at best.

Then it depends on sea state, wind, type of helo and its CoG. I have been taught that if you anticipate a rough landing it's best to stick the tail in to absorb most of the impact forces.
What it does to the main rotor and wheter they will come crashing throug the cockpit, I don't know. But to nose is is certain disaster.

Furthermore, If you're machine has hydraulic controls, make sure you don't position the controls in such a way that your left leg gets physically trapped. To survive you need to be able to exit the aircraft..so think also about wearing a helmet.

And finally, you need a bit of luck. And survival kit to keep you alive outside of the aircraft in a hostile environment like the sea.

[Lu Zuckerman]

If only they kept records.

Back in 1949 the US Coast Guard ran a test to determine the best way to autorotate into the water. They used surplus HOS-1s. I saw several of the landings and ditchings and I believe there were a total of ten or twelve ditchings. They used the data to standardize the method of ditching for USCG and USN pilots. If you are really interested you might contact USCG Headquarters (Aviation section) in Washington DC to see if they kept the records.

The tests took place at the CGAS Elizabeth City, North Carolina sometime between July and December of 1949.

[Rich Lee]

There are many considerations involved in ditching a single (or twin) helicopter at sea following an engine(s) failure. This assumes that the helicopter is not equipped with utility or pop-out floats (a high risk configuration beyond the autorotative distance to land).

Do not forget to open a door(s) or window during the descent and prior to touchdown. A door on a closed cabin helicopter is very difficult to open until pressure is equalized between the outside and inside of the cabin. Should you forget this step you may only be able to open the door when the helicopter is so deep that you or your passengers may find it difficult to swim to the surface.

Use as much rotor energy as possible as you settle into the water. There are debates as to the best way to do this but in my opinion holding full up collective and settling vertically is more effective than an aft cyclic, tail entry method.

Understand sea state and recommended methods for landing in calm or swelling seas. An autorotation into a six foot swell moving at the helicopter creates considerable difficulty for the pilot.

Understand proper methods and use of available instruments and lights to judge flair height. Water is every bit as forgiving as concrete when dropping in from 50 feet.

Use personal flotation devices appropriate to the water temperature and distance from land. Always have them on, not stowed. What you are not wearing will probably not leave the aircraft.

A thorough brief of crew and passengers to include an exit drill or at the very least an exit discussion. This brief must at the very least include methods to open a seatbelt, methods to open a door and when to leave the aircraft (remember the pilot may not be alive or able to give an exit command or instructions).

Use a raft and overwater survival kit. An easily reached breakout knife in case you forgot to open the door is also helpful.