INTERNATIONAL FIRE TRAINING CENTRE

Transcription

1 INTERNATIONAL FIRE TRAINING CENTRE FIREFIGHTER INITIAL INCIDENTS INVOLVING HELICOPTERS Throughout this note he means he/she and his means his/hers. Areas in bold type are considered to be of prime importance. INTRODUCTION It is essential, if incidents involving helicopters are to be dealt with swiftly and safely, that all RFF personnel are familiar with the correct tactics and techniques for both fire fighting and rescue. This note should be studied in conjunction with the helicopter manufacturers information notices, other training notes available at IFTC covering aircraft fire fighting tactics and techniques, ICAO Heliport Manual, Second Edition 1985, Airport Services Manual Part 1 Third Edition 1990 and CAP 168 Chapter 8. The most important factors having a bearing on effective rescue at a survivable helicopter accident will be the previous training received, the effectiveness of extinguishing agents and equipment and the speed with which RFF crews can bring them into use. Although the amount of fuel carried by helicopters is usually less than that carried by fixed wing aircraft, a more serious fire situation can develop very rapidly. This is mainly due to the fact that the fuel tank(s) is located underneath the occupied section of the fuselage and close to the engine. AIMS To introduce the student to the hazards associated with helicopters and the need for and the specific fire fighting tactics and techniques required when dealing with an incident involving a helicopter. OBJECTIVES At the end of this instructional session dealing with this subject, after detailed study of this note and the practical sessions on the fireground you will be able to state: The role of helicopters The construction materials used The associated hazards with helicopters The correct approach and positioning on helicopters. The correct firefighting tactics when dealing with a helicopter incident. CONTENTS Introduction Role of the helicopter Construction and materials in use Hazards Helicopter accidents Approach and firefighting tactics Summary

2 GENERAL INFORMATION The Role of the Helicopter The helicopter is often selected for use because of its capability of gaining access to areas which are completely inaccessible to most other type of aircraft. It is able to fly close to the sides of mountains, hover over clearings or offshore platforms and can fly at low altitude. It is frequently required to operate in hostile environments. Over many years the helicopter has proved its versatility in a wide variety of roles. These include: Short range public, company and private transport Search and rescue both on and off shore Casualty evacuation Fire fighting Police surveillance Utilities are now using helicopters in main role In various other civil roles In various military roles CONSTRUCTION MATERIALS IN USE General The construction of the airframe of a helicopter is similar to the fuselage frame of fixed wing aircraft but generally it is lighter. There are several reasons for this i.e. it is not stressed to carry a mainplane, the cabin is not pressurised for high altitude flight, the undercarriage assemblies are comparatively small, therefore the structure of the helicopter is more likely to include structural members of smaller cross-section. Sheet metal is of very thin gauge and light alloys are used such as Aluminium, Duralumin, Alcad, Magnesium and Elektron. The modern tendency is towards composite materials such as Carbon Fibre Reinforced Plastic (CFRP) and Aramid Reinforced Plastic (ARP). Composite materials are corrosion resistant, very light in weight and very strong. HAZARDS Undercarriages The undercarriage of a helicopter is usually small compared to fixed wing aircraft. It can be fitted with skids, skids and wheels or wheels alone. Some undercarriages are retractable into the fuselage and are fitted with shock-absorbers which may have a pressure of between Bar. Water Actuated Devices Water actuated devices known as buoyancy bags or inflatable bags are fitted to helicopters that operate over water. These bags can be found in wheel hubs, carried in sponsons which are braced to the fuselage by fixed struts, mounted on skids or integral. The bags are intended to give stability to the helicopter on the water in the event of the aircraft having to ditch. On some helicopters an Automatically Deployable Emergency Locator Transmitter (ADELT) is fitted. This unit when released from the aircraft transmits a continuous signal on frequencies and MHz simultaneously thereby allowing responding searching craft to, home in. The ADELT unit maybe attached to the fuselage or the tail cone with the direction of deployment to the rear, downward and slightly outwards. The unit itself deploys by

3 means of a release mechanism squib and subsequent spring pressure to eject the ADELT away from the aircraft. Extreme care should be taken by personnel working in the vicinity of ADELT systems as heavy applications of water could cause deployment. Interior Furnishings The cabin space in helicopters is usually a high proportion of the total volume of the fuselage. Upper reinforced fire bulkheads can be found in the fuselage along with other reinforced bulkheads. Interior furnishings can be similar to fixed wing aircraft with plastics, wool, nylon, rubber etc. being used. Seating arrangements are similar to fixed wing with single or double seats being used. They can be forward facing, aft facing or side on or a combination of each. An elevated flight deck is common on larger helicopters with seating for one or two pilots with the captain sitting in the right hand seat. Engines Most helicopters have turbo shaft engines geared to drive a rotor. The Rolls Royce Gem and Gnome are examples. Positions of engines vary depending on the design of the helicopter. They can be found in the nose section, mounted above the cabin, or pod mounted on the rear rotor pylon as in the Chinook. Where two engines are mounted side by side fire-resisting bulkheads separate them from each other and from the cabin area. Fire access panels are fitted in the engine cowling if enclosed engines are used. Open engines have no need for fire access panels. Some of the smaller helicopters are fitted with piston engines of the open type. The Kawasaki Bell 47 is an example. Fuel Tanks Helicopters such as the Bell 47 have metal tanks mounted on either side of the engine. Most helicopters have fuel contained in tanks positioned under floor. These tanks are similar to those used in fixed wing aircraft such as integral, flexible and rigid. Auxiliary fuel tanks can be fitted to most helicopters and can be either internal or external. Fuel tanks are routed from the floor area through the fuselage to the engines. Rotors The number of rotor blades varies from helicopter to helicopter but normally it is between 2-5 blades but in some cases more. The diameter can be as much as 19m. They are usually constructed of light alloy such as aluminium or titanium. There is a tendency with modern day construction towards a combination of metal and CFRP. This blade can shatter on contact with the ground. Portions of the blade can be thrown considerable distance with great force. Tail Rotors The number of tail rotor blades does vary but is normally between 2-5. The tips of the rotor blades on most helicopters are painted in bright colours for identification purposes. The tendency of today s design is to have ducted tail rotors as in the Dauphin. HELICOPTER ACCIDENTS Being of light construction the helicopter is more likely to suffer structural damage than a fixed winged aircraft under crash conditions from altitudes below 15m. Undercarriage components, rotors and tail sections may break off leaving the fuselage as the main wreckage. This part of the wreckage will normally contain engines, passengers and fuel tanks. The

4 lack of mainplanes make the helicopter more likely to roll onto its side. Thus resulting in possibly 50% of exits being unavailable for egress. Also ladders may be required to gain entry up to the aircraft and also down into the main section. Cutting tools may be necessary to extricate trapped occupants. Military helicopters may be armed with various weapons and under crash conditions great care must be taken with regard to approach, fire fighting and rescue. APPROACH AND FIRE FIGHTING TACTICS Approach The approach to any incident involving aircraft can be extremely hazardous depending on the nature and seriousness of the particular incident. It is impossible to set down precise instructions and the following is therefore intended to provide guidance in order to assist the decision making process on arrival. Factors to be considered position of aircraft damage sustained by aircraft type of aircraft i.e. military or civil any passengers or crew visible on arrival fire situation on arrival are engines running? are rotors turning? RFFS personnel should on arrival at the scene of an incident involving a helicopter take particular care when deciding on the initial positioning of appliances. It must be remembered that rotor blades invariably extend a considerable distance from and around the main body of the aircraft. When attending incidents involving military helicopters RFFS personnel should consider the required tactics for dealing with military aircraft in general. Never approach military aircraft directly from the front or rear as these are the main danger areas in relation to any weapons on board. Approach military helicopters at a 45 o angle from the front or rear. Helicopter incidents at which engines are running and rotors turning If on arrival at the scene aircraft engines and the rotors are still turning, urgent consideration must be given as to the need to approach close to the aircraft. In such situations urgent contact with the aircraft crew should be established and only action required to save life or prevent fire from affecting the fuselage should be taken. In this case great care must be exercised in approaching the aircraft paying particular regard to both main and tail rotors. Personnel should approach in a crouching position bearing in mind that that as the rotors slow they will continue to sag and in many cases sagging below average height head level. Extreme care must be taken when fire fighting and working rescue equipment under such conditions, with equipment at the scene being carried below waist level. In situations where the pilot is conscious and able to give instructions, approach in full view of him and follow his directions. Avoid blind areas of the helicopter where the pilot cannot see you. Under crash conditions where the pilot is incapacitated it may be advisable to approach from the rear of the helicopter. Keep to the opposite side of the tail from that of the stabilising rotor and remain close to the fuselage. Entry into the main fuselage can be made with the minimum of danger to the firefighter as the main rotor is designed to rise above the tail. This applies only to crash conditions. Normally approach in full view of the pilot and obey his instructions. Approach the helicopter from the downhill side if possible. Never approach or leave from the uphill side. Carry tools or equipment below waist level and make sure chinstraps are secure on helmets. Do not slam the doors on helicopters; close them gently and do not let them swing in the wind.

5 Personnel must avoid engine air intake and exhaust efflux areas. When water actuated devices are fitted into the wheel hubs care must be taken not to stand directly at the side of the wheels in case the disc which covers the device blows off. This could cause serious injury to nearby persons. A direct jet of water could activate the device. Helicopter incidents at which aircraft engines and rotors have been shut down prior to arrival If on arrival at the scene it is apparent that the aircraft engines and rotors have been shut down, action, in the case of civilian helicopters, can in general follow the tactics and techniques used for fixed wing aircraft. However RFFS crews should bear in mind devices peculiar to helicopters such as floatation devices and ADELT systems as referred to above. In addition crews should bear in mind that owing to the particular design features of a helicopter any fire occurring may quickly enter the cabin if not speedily dealt with. Owing to the fact that helicopter design results in the use of lightweight (thin) construction materials, it is imperative that the fuselage is immediately isolated from any fuel fire taking place. All fuel spillage s which have occurred must be covered with aspirated foam and this blanket maintained throughout the duration of the incident. Initially and in order to ensure a rapid knockdown of any fire, appliance mounted monitor(s) should be put to work immediately on arrival with supporting aspirated foam side lines being simultaneously deployed. In order to conserve media, monitors should be knocked off immediately the fire is brought under control and the side lines charged and brought into operation. Once the initial fire has been extinguished, supplies of fire fighting media should be preserved by their carefully considered use. An entry into the aircraft cabin and cockpit areas to carry out rescue is the priority which must be considered simultaneously to controlling the fire. Any evacuating crew and/or passengers should be removed to a place of safety upwind on the incident. Charged guard branches (aspirated foam) must be maintained throughout the duration of the incident. At incidents where pressurised flammable liquids or running fuel fires are involved the use of a dual application of foam/dry powder foam CO 2 foam/halon should be considered. Care must be taken when working with pressure jets to ensure that any water actuated devices fitted to the aircraft are not inadvertently activated (see above section dealing with hazards). Owing to the potential for a fire to subsequently ignite or re-ignite whilst rescue operations are in progress charged lines should be taken into enclosed cabin areas by rescue crews and manned charged guard lines maintained outside. Under no circumstances should water supplies feeding hose lines at work inside the aircraft be cut off. Some helicopters have large amounts of magnesium or composite materials used in their construction. Magnesium, being a combustible metal, will burn readily if its ignition temperature is reached. Water spray can be used to accelerate the rate of burning and to cool the unaffected parts keeping them below their ignition temperature but great care must be exercised when doing this as magnesium will react violently to water and most fire service media s except a D Class powder. Full protective clothing must be worn with visors down. In general, carbon fibre composites when used in aircraft structural applications will not readily ignite. They will resist ignition for some time even when exposed to the high temperatures likely to be encountered at the scene of an aircraft fire situation. All RFFS personnel should be dressed in full protective clothing ensuring that helmet chinstraps are secure. Where personnel are required to work in smoke and/or fumes or it is suspected that other airborne contamination may be present breathing apparatus should be worn.

6 Fires involving large passenger carrying or laden cargo aircraft may be protracted, particularly if casualties are trapped inside the wreckage. Where such a situation exists early consideration should be given to the provision of additional water supplies. SUMMARY Incidents involving helicopters can, if not dealt with speedily and effectively by the Rescue and Fire Fighting Services (RFFS), quickly develop into a serious fire situation in which loss of life may occur. Following a serious incident, the most important factors which can improve the chances of survival are: The previous training and experience of the RFFS crews involved The effectiveness of the extinguishing agents, equipment, tactics and techniques employed The speed with which the RFFS respond, gain control over any resulting fire situation and effect rescue Although the approach and tactics may be similar to that of fixed wing aircraft. RFFS crews should be aware of the additional hazards such as: Rotors Water actuated devices; ADELT transmitters Military aircraft Isolation of the fuselage from any fire should be undertaken with the utmost haste. REMEMBER Always exercise caution around helicopters. Be alert around the helicopter and live