Under-seat liferaft installation

[Geoffersincornwall]

Has anyone got a photograph of a typical under-seat liferaft installation as used on many S76 models?

Thanks

G
:ok:

[mtoroshanga]

The under seat instaltion is not the best option, the latest idea is to have the rafts in external gondolas which are a far more elegant option.

[RedWhite&Blue]

As you will remember from Denes not much to see when installed. What aspect do you need a photo of. I will try to take photos in the next day or two.


Mtoroshanga, elegant... umm not so sure. We have one 76a+ fitted with the conformal pods. It doesn't fly much. Many of the drivers fear that thay would be flying when a nutter in the back pulled one of the handles in flight.

For those who don't know the rafts in question, they are fitted outside the aircraft with three cable controlled jettison handles. One for the crew and two in the main cabin. They are guarded with plastic/velcro guards.

They were fitted at the request of Mobil, but no one ever explained why they were required for that customer.

I'd love to know their real advantages.

ATB

Red

[Brian Abraham]

I'd love to know their real advantages
Getting a raft out from under the seat following a ditching is going to be an interesting exercise in its self. Trouble with the 76 under seat set ups that I've seen rely on the seat legs to restrain the raft in the event of any "g" loads being applied. This is counter to the standards to which the seats are designed ie NOT PERMITTED. It seems to be that operators have said "Here's a good place to stick a raft" without any engineering analysis being done and the regulators turning a blind eye. We asked Sikorsky the question and they said "yes, OK, provided the seat itself did not have any loads transferred to it in the event of an accident". An accident (in the GOM I think it was) where a 76 went into the water the seat collapsed onto the raft so that it was unable to be extracted. Think about what it might do to the pax's spines when the seat collapses onto the raft as well (R22 guys who use the under seat area for storage have not fared too well re spinal injuries in accidents). Our aircraft were retro fitted with the external rafts with operating handles in the cockpit and external - there were no handles the pax could access inside the aircraft.
http://i101.photobucket.com/albums/m56/babraham227/76.jpg
In the photo the raft is in the pod just below the rear door (one raft each side), external operating handle at the forward end of the pod.

[Nigel Osborn]

That would have to be an Australian 76 with a boomerang for a rotor blade.:ok:

[ScotiaQ]

The conformal liferafts were a US STC and when tested, with UKCAA Observance, they failed to deploy. Modifications were made but the mode of jettison is still a Heath Robinson affair.

The current underseat liferafts, as used by CHC, are contained within a Fibrelam Box and the box is structurally mounted to the cabin floor. There is no question of the seat restraining the liferaft.

The later conformals may be have been improved, I don't know.

[Geoffersincornwall]

Thanks for the offer. A general photo of the installation as seen from either side outside with the door wide open would be much appreciated. That should do nicely for my purpose which is to help in the discussions about the 'old' way of doing things and how it should be done - external rafts designed into the structure from the outset. a la AW139.

Thanks again

G:ok:

[FloaterNorthWest]

Geoff,

Alan Mann Engineering have and are fitting the external liferafts to the new Bristows S76C++ for the UK and Kazakstan. After a few initial teething problems (inadvertant inflation due to poor firing mechanism design) they seem to be working fine. I below the firing handle is now fitted in the front.

Give them a ring I am sure they can help you.

I agree with the comments about not putting things under seats if they are designed to deform as a mechanism to absorb vertical G forces. It's no good having a non-deforming box with a liferaft in if you have 16 stone of rigger with spinal injuries on top of it blocking access.

FNW

[RedWhite&Blue]

Brian, you say "Getting a raft out from under the seat following a ditching is going to be an interesting exercise in its self." I hope not.

Ours have three methods of deployment.

Firstly they can be elecrically deployed. Haveing fired the guarded switch in the cockpit the LHS car type door has its hinge pins withdrawn by a motor. Following a four second delay, to allow the door to fall/float away, a squib fires allowing compressed gas to fill bellows which push the raft out of its housing. One steps calmly aboard the raft in an orderly fashion, women and chilren first.;)

If that doesn't work the door is jetisoned in the normal manner and handles attached to bowden cables can be used to fire the squib to fill the bellows.

If everthing else has failed the raft can be manually haulled from its housing through either door.

Now everything has its pros and cons, you pays your money and takes your choice.

But, how in a heavy dithing will the conformal pod rafts fair behind their lightweight cowlings? What if the cowls open in flight?

And Geoffers, one of our 139 has alerady had the band/straps which hold the shells together (in which the life raft is held above the main gear sponson) break/un-weld in flight. Luckly only one of the three on each side went. A tethered life raft in the tail rotor might spoil your day! You can bet we check those straps well on a walk round!

I'm not saying anything is better than..... just some thoughts.

ATB

Red

[Geoffersincornwall]

Mmmmmm....interesting. Well the idea is the right one I have no doubt, that is having the right product designed and integrated at the design stage rather than having to produce a 'work-around' - even if it's a good one. The question, as always with choppers, does the design work in the real world. I hope the AW engineers are producing a 'fix' and I will follow that up when I see one of my colleagues from the factory.

Any chance of a piccy?

Thanks

G
:ok:

[peterperfect]

Geoffers,
I know your original thread requests underseat raft info, my view is that OGP is gently pushing for external conformals in all the 76s if possible.

However if you havn't seen it already there is some good reference reading concerning post-ditching survival and egress, just google: "caa helicopter ditching survivability" to obtain the 2005/2006 research paper,

also CAP 641 of course can be downloaded: that touches on post ditching issues and survival.

Anything to remove the passenger element of first having to locate the rafts and then deploy them must be a good thing, if the S76 conformal rafts are not deployed by the left seat pilot from inside ( a girt handle on the left side of the centre column) and the thing inverts there are always manual d rings either side on the underside of the hull.



I am not a great fan of the cargo-door mounted 'external' raft mod, it puts strain on the hinges and reduces boot space, and frankly is not too Jack-proof either

Not sure if the 76D will jave them as standard for offshore variant.

This is all on the mitigation side of the risk assessment, but lets face it, it would be a real shame to survive the ditching but not survive the survival.

Regards from the other side of the three spires, pp

[Brian Abraham]

RedWhite&Blue - sounds as though your set up is properly engineered with a great deal of thought and work. Ours was merely two rafts jammed under the seat and could be a hell of a job dragging them out while standing on the ramp, let alone being in the water and trying to do the same - hence the comment.
how in a heavy dit(c)hing will the conformal pod rafts fair behind their lightweight cowlings? What if the cowls open in flight
You certainly make a fair point about the pods surviving a heavy ditching, the things are packed so tight that I opine they may be OK. Never had any concern about them opening in flight and with over 10 years of operation have been trouble free. Would get rid of handles accessable to pax though.

[mtoroshanga]

On the subject of underseat fitment, the other dingy is a heath-robinson affair at the side of the Captains seat which can cause hastle when closing the door.

[Camp Freddie]

mtoroshanga,

we have exactly the same fit as RedWhite&Blue and the right hand raft is the same as the left except, the door jettison is not present, therefore it has 2 methods of deployment as against 3 for the port side.

the pilots door installation has gone on our aircraft years ago.

I think it is a good system

regards

CF