Are floats strong enough to......
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Joined: Nov 2003
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From: east
Are floats strong enough to......
Flying offshore,it is very cold,sea is iced but not thick enough to support the helicopter.so I was thinking,if we had to ditch,the fragmentized pans of ice could damage the float bags,????????
Better red than ...
Joined: Aug 2004
Aviation Qualifications: CPL
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From: Appleby-in-Westmorland Cumbria England
Depends on the thickness of the ice pan?
And the force of impact on touchdown? I guess 'running on' would be more damaging than a firm vertical touch on the ice?
Take extra woolly hat and gloves if practicing.
And the force of impact on touchdown? I guess 'running on' would be more damaging than a firm vertical touch on the ice?
Take extra woolly hat and gloves if practicing.
Joined: Apr 2002
Posts: 687
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From: Up north
Floats are highly unlikely to be damaged by ice so long as they are inflated before touch down and touch down is vertical. The rubberised fabric they are made of appears tougher than our liferafts and will lift the nose gear of a Dauphin just about clear of the tarmac. (done that!!)
HF
HF
Joined: Oct 2003
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From: Over here
Popout floats don't even last that long in warm, flat seas all the time. The only thing the floats are for is to give you time to get out of the helicopter. In cold seas, wear an immersion suit, have a life raft handy, and get into it ASAP. The floats will will fail, sooner or later, and with lots of ice, probably sooner. A twin-engine helicopter would be a wonderful idea.
Look on my works, ye mighty, and despair.
Joined: Apr 2002
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From: Floatin' on th' Black Pig, Yarr!
It depends on the type of float and where they were manufactured. The best material......and the most expensive.......is kevlar coated with polyurethane. Modern spinny wing things like S92 and EH101 use this material.
Older materials such as s61 tend to be nylon/polyurethane or nylon/rubber and are less resistant than the modern ones.
If your purchasing department get their spares from a PMA shop in the outback of mexico then you had better take off with a drybag and a flask of soup.
Older materials such as s61 tend to be nylon/polyurethane or nylon/rubber and are less resistant than the modern ones.
If your purchasing department get their spares from a PMA shop in the outback of mexico then you had better take off with a drybag and a flask of soup.
Joined: Mar 2002
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From: Iceland
B212 float test.
It is important to land vertically with as little or no forward motion as possible if the floats are released in flight. I have been told that they can be ripped of if landing with forward airspeed as they are designed to lift the helicopter up and not act as water brakes
For those that do not know. The B212 & B222 have 4 float sensors under the belly and if two of them are submerged the floats will release within 2-3 seconds automatically with the floats armed.
The floats are usually armed for take offs/ landings over water below 500´ & 50 kts.
It is important to land vertically with as little or no forward motion as possible if the floats are released in flight. I have been told that they can be ripped of if landing with forward airspeed as they are designed to lift the helicopter up and not act as water brakes
For those that do not know. The B212 & B222 have 4 float sensors under the belly and if two of them are submerged the floats will release within 2-3 seconds automatically with the floats armed.
The floats are usually armed for take offs/ landings over water below 500´ & 50 kts.
Joined: Jun 2003
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From: Off the Planet
Aesir:
This is a myth that cannot go uncommented; the following is taken verbatim from AC 29.801 - look particularly at paragraph (C):
There are separate critieria for helicopters which have not been certificated for ditching and are equipped with emergency floats.
It is important to land vertically with as little or no forward motion as possible if the floats are released in flight. I have been told that they can be ripped of if landing with forward airspeed as they are designed to lift the helicopter up and not act as water brakes
b. Procedures. The following guidance criteria has been derived from past FAA/AUTHORITY certification policy and experience. Demonstration of compliance to other criteria may produce acceptable results if adequately justified by rational analysis. Model tests of the appropriate ditching configuration may be conducted to demonstrate satisfactory water entry and flotation and trim characteristics where satisfactory correlation between model testing and flight testing has been established. Model tests and other data from rotorcraft of similar configurations may be used to satisfy the ditching requirements where appropriate.
(1) Water entry.
(i) Tests should be conducted to establish procedures and techniques to be used for water entry. These tests should include determination of optimum pitch attitude and forward velocity for ditching in a calm sea as well as entry procedures for the highest sea state to be demonstrated (e.g., the recommended part of the wave on which to land). Procedures for all engines operating, one engine inoperative, and all engines inoperative conditions should be established. However, only the procedures for the most critical condition (usually all engines inoperative) need to be verified by water entry tests.
(ii) The ditching structural design consideration should be based on water impact with a rotor lift of not more than two-thirds of the maximum design weight acting through the center of gravity under the following conditions:
(A) For entry into a calm sea--
(1) The optimum pitch attitude as determined in 337(b)(1)(i) with consideration for pitch attitude variations that would reasonably be expected to occur in service;
(2) Forward speeds from zero up to the speed defining the knee of the height-velocity (HV) diagram;
(3) Vertical descent velocity of 5 feet per second; and
(4) Yaw attitudes up to 15°.
(B) For entry into the maximum demonstrated sea state--
(1) The optimum pitch attitude and entry procedure as established in
(2) The forward speed defined by the knee of the HV diagram reduced by the wind speed associated with each applicable sea state;
(3) Vertical descent velocity of 5 feet per second; and
(4) Yaw attitudes up to 15°.
(C) The float system attachment hardware should be shown to be structurally adequate to withstand water loads during water entry when both deflated and stowed and fully inflated (unless in-flight inflation is prohibited). Water entry conditions should correspond to those established in paragraphs AC 29.801(b)(1)(ii)(A) and (B). The appropriate vertical loads and drag loads determined from water entry conditions (or as limited by flight manual procedures) should be addressed. The effects of the vertical loads and the drag loads may be considered separately for the analysis.
(D) Probable damage due to water impact to the airframe/hull should be considered during the water entry evaluations; i.e., failure of windows, doors, skins, panels, etc.
(1) Water entry.
(i) Tests should be conducted to establish procedures and techniques to be used for water entry. These tests should include determination of optimum pitch attitude and forward velocity for ditching in a calm sea as well as entry procedures for the highest sea state to be demonstrated (e.g., the recommended part of the wave on which to land). Procedures for all engines operating, one engine inoperative, and all engines inoperative conditions should be established. However, only the procedures for the most critical condition (usually all engines inoperative) need to be verified by water entry tests.
(ii) The ditching structural design consideration should be based on water impact with a rotor lift of not more than two-thirds of the maximum design weight acting through the center of gravity under the following conditions:
(A) For entry into a calm sea--
(1) The optimum pitch attitude as determined in 337(b)(1)(i) with consideration for pitch attitude variations that would reasonably be expected to occur in service;
(2) Forward speeds from zero up to the speed defining the knee of the height-velocity (HV) diagram;
(3) Vertical descent velocity of 5 feet per second; and
(4) Yaw attitudes up to 15°.
(B) For entry into the maximum demonstrated sea state--
(1) The optimum pitch attitude and entry procedure as established in
(2) The forward speed defined by the knee of the HV diagram reduced by the wind speed associated with each applicable sea state;
(3) Vertical descent velocity of 5 feet per second; and
(4) Yaw attitudes up to 15°.
(C) The float system attachment hardware should be shown to be structurally adequate to withstand water loads during water entry when both deflated and stowed and fully inflated (unless in-flight inflation is prohibited). Water entry conditions should correspond to those established in paragraphs AC 29.801(b)(1)(ii)(A) and (B). The appropriate vertical loads and drag loads determined from water entry conditions (or as limited by flight manual procedures) should be addressed. The effects of the vertical loads and the drag loads may be considered separately for the analysis.
(D) Probable damage due to water impact to the airframe/hull should be considered during the water entry evaluations; i.e., failure of windows, doors, skins, panels, etc.
Look on my works, ye mighty, and despair.
Joined: Apr 2002
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From: Floatin' on th' Black Pig, Yarr!
.....and to be honest it depends on your reason for ditching.
The best chance of survival is to make as controlled an impact into the water as possible and let the auto inflate decide when to deploy the floats.
Many years ago a ch46 driver on an unplanned rapid decent deployed the floats before hitting and tore the aircraft in half along the centre like it had a zipper. it makes exit very rapid but through the door is better than through the floor.
The best chance of survival is to make as controlled an impact into the water as possible and let the auto inflate decide when to deploy the floats.
Many years ago a ch46 driver on an unplanned rapid decent deployed the floats before hitting and tore the aircraft in half along the centre like it had a zipper. it makes exit very rapid but through the door is better than through the floor.
Joined: Mar 2002
Posts: 814
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From: Iceland
Aesir wrote:
quote:
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"It is important to land vertically with as little or no forward motion as possible if the floats are released in flight. I have been told that they can be ripped of if landing with forward airspeed as they are designed to lift the helicopter up and not act as water brakes."
Back to the original post regarding ditching in icy waters.. the floats could get ripped off if landing with forward moment where ice is present no matter what any certification requirements say.
I was probably not clear enough about what I meant.
quote:
--------------------------------------------------------------------------------
"It is important to land vertically with as little or no forward motion as possible if the floats are released in flight. I have been told that they can be ripped of if landing with forward airspeed as they are designed to lift the helicopter up and not act as water brakes."
Back to the original post regarding ditching in icy waters.. the floats could get ripped off if landing with forward moment where ice is present no matter what any certification requirements say.
I was probably not clear enough about what I meant.
