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Aviation History
1984
1984 - 0014.PDF
CIVIL HELICOPTERS Now get out of that We will shortly hit the water. After check ing that our seat belts are tight, hoods up, and life jackets secure, we grip the seats tightly, straightening our backs, ready for impact. Immediately after impact, water gushes in through the open escape hatches and the unstable fuselage begins to capsize and sink. Before going under, one hand is moved to the seat belt buckle and the other to the edge of the escape hatch or the next seat so that we do not need to open our eyes underwater, and we should not suffer disorientation. As the frothing water reaches knee height there is a sudden impulse to release the seat belt and attempt to escape from the cabin before being submerged. This urge must be resisted, because if you do unbuckle you will be thrown around the rotating cabin like washing in a spin drier. You will not know which way is up, or more importantly, which way is out. As the water reaches chin height we are rotating through about 30° and we all take what will be our last breath for a while. It is important to time this right. Take your breath too early and you will be thinking very hard about a second one while hang ing upside down in your seat underwater. Too late, and you risk a mouthful of water and then you have to release the seat belt and go for the air pocket, always upper most in the cabin. Instead of allowing the water to submerge our heads as it rises, we push our heads under deliberately towards the nearest escape hatch. This helps to prevent the last-minute panic, and we are now surrounded in a swirling, rotating Ian Parker tries the Robert Gordon Institute of Technology's method for escaping from a capsized and sinking helicopter. world of bubbles, distorted images, and strange sounds. The angular momentum of the fuselage is high, so it rotates past the inverted and oscillates a few times. This takes a few seconds to stop, but we remain strapped in while the motion dies away. Otherwise the escape hatch is moving as you try to go through it and you get the edge across the back of the neck or up the nostrils. All this seems to take a very long time, but at last we are in inverted equilibrium. Seat belts are released and we exit quickly. I surface first, followed by three others and we all inflate our life jackets. We swim to the edge of the pool and climb out. Being in a ditched helicopter is one of the offshore oil worker's worst fears. It is a very rare occurrence, but unless the sea is calm there is some chance that the heli copter will capsize and sink. Flotation bags are often fitted, but a helicopter is unstable on the water because most of the weight—engines, dynamics, rotors, etc— is at the top. Operators brief their passengers on how to escape from a ditched helicopter and survive in the water, but of greater benefit is actually experiencing it under con trolled conditions. At the Robert Gordon Institute of Technology's (RGIT) Offshore Survival Centre in Aberdeen, oil workers and aircrew can practice survival techniques. The centre's Helicopter Underwater Bouyancy tanks at either end turn the Huet over when the hydraulic brake is off. A circular track and roller allow rotation Escape Trainer (Huet) is one of only two such devices in the UK, and it allows people to practice the escape procedures so often only shown on diagrams or pointed out by flight attendants. Flight had the opportunity to experi ence the Huet recently. Students are introduced to the full capsize in stages. The first exercise simulates a controlled ditching in which the aircraft remains upright, but floods to about knee depth. An orderly evacuation through the normal exit is practised. On the second lowering the Huet sinks until the occupants are submerged. Each person counts seven seconds to allow the imaginary rotor to stop turning and then escapes. Survival centre assistant manager David Hill says "We have to make sure that shorter students occupy the outer seats. Their heads will go under first and they may be well into their seven-second count before the taller ones start counting". The shorter students therefore try to escape first and if they are in the middle, it can be disturbing for them to find some large chap in the way. People do tend to count at different rates, but the onboard instructor gives everyone leave to provide "encouragement" to any sluggish neigh bour, and the instructor ensures a safe and orderly departure. The capsize exercises are optional, but about 97 per cent of swimmers and 64 per cent of non-swimmers go through all stages. Non-swimmers are identified by red helmets so that a special eye can be kept on them. There are always two scuba divers in the water waiting to extricate anyone who has difficulty. Apparently the divers watch trainees' eyes for signs of panic. Building confidence is seen as a major part of RGIT's training and no one is forced to go through the Huet. Some trainees are understandably worried at the thought of being "dunked", but most come out smiling and some are keen to have another go. About 100 trainees a week go through the Huet, usually as part of a general survival course, but if Huet training only is required, it can be completed in an afternoon for £40 a person. About 5,000 people have been through it to date, and the equipment operates 46 weeks a year. Aircrew training is made more realistic by additional exercises carried out in dark ness and with all participants exiting through one window. Some years ago it was realised that an escape trainer would be a valuable addi tion to the survival training facilities at the Offshore Survival Centre and, after RGIT staff had visited the Royal Navy 14 FLIGHT International, 7 January 1984
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