Bell 212 Helicopter

The Bell 212 (also known as the Twin Two-Twelve) is a two-blade, twin-engine, medium helicopter that first flew in 1968. Originally manufactured by Bell Helicopter in Fort Worth, Texas, United States, production was moved to Mirabel, Quebec, Canada in 1988, along with all Bell commercial helicopter production after that plant opened in 1986. 

The 212 is marketed to civilian operators and has a fifteen-seat configuration, with one pilot and fourteen passengers. In cargo configuration the 212 has an internal capacity of 220 ft³ (6.23 m³). An external load of up to 5,000 lb (2,268 kg) can be carried. 

Development

Based on the stretched fuselage Bell 205, the Bell 212 was originally developed for the Canadian Forces as the CUH-1N and later redesignated as the CH-135. The Canadian Forces took delivery of 50 starting in May 1971. At the same time the United States military services ordered 294 Bell 212s under the designation UH-1N. 

By 1971 the 212 had been developed for commercial applications. Among the earliest uses of the 212 in civil aviation was by Helicopter Service AS of Norway to be used in support of offshore oil rigs. Today the 212 can be found used in logging operations, maritime rescue and resupply in the Arctic on the Distant Early Warning Line or North Warning System.

The 212's main rotor is powered by a Pratt & Whitney Canada PT6T-3 Twin-Pac made up of two coupled PT6 power turbines driving a common gearbox. They are capable of producing up to 1,800 shp (1,342 kW). Should one engine fail the remaining engine can deliver 900 shp (671 kW) for 30 minutes, or 765 shp (571 kW) continuously, enabling the 212 to maintain cruise performance at maximum weight.

Early 212s configured with an Instrument Flight Rules (IFR) instrument package were required to have a large and very obvious fin attached to the roof of the aircraft, above and slightly behind the cockpit. This fin was initially determined necessary to alter the turning performance of the aircraft during complex instrument flight maneuvers, but is no longer required due to revised stipulations of the type certificate. Many aircraft still fly with the modification.

In 1979, with the purchase of eight by the Civil Air Authority, the 212 became the first U.S. helicopter sold in the People's Republic of China.

The ICAO designator for this aircraft as used in a flight plan is "B212". Bell developed the Model 212 further with the Bell 412; the major difference being the composite four-blade main rotor. The last Bell 212 was delivered in 1998.

Variants

• Bell Model 212 - Bell Helicopters company designation for the UH-1N.
• Twin Two-Twelve - Civil utility transport version. It can carry up to 14 passengers.
• Agusta-Bell AB 212 - Civil or military utility transport version. Built under license in Italy by Agusta.
• Agusta-Bell AB.212ASW - Anti-Submarine Warfare variant of AB.212
• Bell Model 412 - Bell 212 with a four-bladed semi-rigid rotor system.
• Eagle 212 Single - Single engine variant with a Lycoming T53-17 or T53-BCV engine produced by Eagle Copters of Calgary, Alberta, Canada.

Specifications (Bell 212)

Cockpit

General characteristics

• Crew: 1 (two for IFR operation)
• Capacity: 14
• Length: 57 ft 1.68 in (17.43 m)
• Rotor diameter: 48 ft (14.64 m)
• Height: 12 ft 6.83 in (3.83 m)
• Disc area: 1,809.5 ft² (168.3 m²)
• Empty weight: 6529.4 lb (2961.7 kg)
• Max. takeoff weight: 11,200 lb (5,080 kg)
• Powerplant: 1 × Pratt & Whitney Canada PT6T-3 or -3B turboshaft, 1,800 shp (1,342 kW)

Performance

• Never exceed speed: 120 knots (138 mph, 223 km/h)
• Maximum speed: 120 knots (138 mph, 223 km/h)
• Cruise speed: 100 knots (115 mph, 186 km/h)
• Range: 237 nm (439 km)
• Service ceiling: 17,400 ft (5,305 m)
• Rate of climb: 1,745 ft/min (532 m/min)
• Disc loading: 6.19 lb/ft² (30.22 kg/m²)

Source: Bell 212 Rotorcraft Flight Manual

Offshore Helideck Design Guidelines

 

Helideck

This article provide general guidelines for layout of Helideck on offshore platforms. It is important that the local aviation regulations are adhered to in all cases. Helideck design shall take into consideration the following items, as a minimum:

• Size and structural adequacy for selected helicopter
• Orientation with respect to prevailing winds
• Gas / exhaust emissions and turbulence environment
• Effects of vessel motions
• Suitable helideck height
• Clear landing approach and take-off paths
• Obstructions within permitted limits
• Falling gradient of 5:1
• Access and escape routes
• Parking arrangements, if provided
• Lighting
• Markings
• Friction surface
• Tiedowns
• Helideck net and perimeter safety net
• Refuelling facilities
• Firefighting equipment

The helideck should be located on the highest level of the platform to ensure that the helicopter approaching and departing the platform is free from any obstructions due to cranes, turbine exhausts, flare booms or any other tall structures.

Size of Helideck

For design purposes, the dimensions of the helicopter are critical for sizing the helidecks, while the maximum gross weight of the helicopter is critical in terms of the structural loads to be borne by the supporting helideck structure. The key characteristic used to size the helideck for design purposes is the “D Value” for the critical helicopter. This dimension reflects the maximum overall dimension of the critical helicopter when its rotors are turning. For a single rotor helicopter this means the length of the aircraft from the extremity of the rotor circle at the front of the helicopter to the extremity of the tail rotor at the rear of the helicopter. For example, the D value for Bell 212 helicopter is 17.46m and D value for AW 139 helicopter is 16.66m.

Orientation with respect to prevailing winds

The prevailing wind direction in the vicinity of the proposed helideck will dictate the direction of flight operations for helicopters landing or taking off from the proposed offshore structure. In the critical phases of touching down on, or lifting off, a helideck it is most important that helicopters are aligned into wind, since at these times these aircraft are susceptible to the effects of crosswinds.

All attempts should therefore be made to ensure that the approach and takeoff orientations are aligned as close as possible into the prevailing winds.

Exhaust emissions and turbulence environment

Offshore installations topsides tend to include a number of tall structures such as drilling derricks, flare towers, cranes, gas turbine exhaust stacks etc. Usually it is impractical to locate the helideck at a higher elevation. All such tall structures will cause areas of turbulence that may potentially pose a hazard to the helicopter. It should be noted that the location and configuration of drilling derricks can vary during the life of the field. The assessment of the helideck location should take into account the various derrick configurations that are expected to occur during the life of the installation.

Obstacle Free Sector

A minimum 210° obstacle free sector is required. Its point of origin on the inboard side of the deck is the apex of the chevron marked on the helideck. By extending a line out from each leg of the chevron, a check is required to ensure freedom from obstructions within the 210° sector by identifying items that are above deck level. Such items may not exceed 250 mm in height, and even then must be restricted to specified essentials such as lighting fittings, safety net rails, etc. as specified in CAP 437. Helidecks are normally located on the platform corners remote from the other facilities in order to comply with 210° obstruction-free sector, and for best aerodynamic performance.

Falling Gradient

The falling gradient sector comprises a 180° arc that falls within the 210° Obstacle Free Sector , and extends downward from the edge of the safety net of the helideck towards the water line at a slope of 5:1. Helideck should be provided with an unobstructed 5:1 falling gradient below the landing area. This unobstructed space permits the helicopter to descend safely after take off in the event of engine failure, so as to "fly away" climbing speed.

Access and escape routes

The personnel access and egress points must be optimally located in terms of their alignment relative to the helicopter parking position. The personnel access and egress points for the helideck must be situated in a position so that access can be gained to the helicopter without interference with the helicopter’s tail rotor. Similarly the passengers leaving the helicopter should not be exposed to the tail rotor. In other words, the access and egress points must be located away from the rotating tail rotor of a parked helicopter. The design should ensure that the egress from the helideck under emergency situations can be made in the safest possible manner.

Helideck Markings

Markings provide critical information to flight crews when approaching, operating on, and departing from a helideck. They are an essential safety feature for the operation of aircraft using the helideck and are required under the ICAO Annex 14 standards. Particular markings that must be provided on a helideck are:

• A large “H” marking, placed in the centre of the helideck, oriented in the direction of the flight approach, conforming to a specified size and dimensions
• A Touchdown/Position Marking surrounding the “H”
• An Obstacle Free Area Marking denoting the origin and direction of the Obstacle Free Surface
• A Helideck Perimeter marking
• The Helideck D-Value
• The Helideck Name
• The T-Value of the heaviest helicopter for which the helideck is designed to accommodate

Rescue and Fire Fighting Services

The purpose of having a fire-fighting capability on a helideck is not to safeguard those who may be present on the structure at any time, but to provide an ability to suppress a fire on a helicopter that may be on fire when landing on the helideck, or catches fire after landing. The essential purpose of helideck fire suppression is therefore related to the operation of the helicopter, and the need to suppress or extinguish a helicopter fire, especially a fuel fire, and to enable occupants of the helicopter to escape from a burning aircraft. As far as the Rescue & Fire-fighting requirements for helidecks is concerned, ICAO Annex 14 Volume II establishes that the fire-fighting requirements specified for helidecks in the ICAO Heliport Manual should be met. This defines the required helideck fire-fighting capabilities to comprise those required under the “Code for the Construction and Equipment of Mobile Offshore Drilling Units” published by the International Maritime Organisation (IMO). The IMO requirements specify that helidecks should be equipped with the following:

• At least 2 dry powder extinguishers having a total capacity of not less than 45kg
• A suitable foam application system consisting of monitors or foam-making branch pipes capable of delivering foam solution to all parts of the helicopter deck at a rate of not less than 6 L/min for at least 5 min for each square metre of the area contained with a circle of diameter “D”
• Carbon dioxide extinguishers of a total capacity of not less than 18kg or equivalent
• At least two dual purpose nozzles and hoses sufficient to reach any part of the helicopter deck

The above are the current requirements for helideck fire-fighting capability, which are not mandatory as far as ICAO is concerned, although it is noted by ICAO that these requirements ‘should’ be met.

Source: Piping World

Aerocraft: Rooivalk Attack Helicopter, South Africa

Aerocraft: Rooivalk Attack Helicopter, South Africa

1.Specifications:

Key Data:

Crew

Pilot, weapon systems officer

Missions

Anti-armour, ground suppression, anti-helicopter, ferry, reconnaissance and counter-insurgency

Dimensions:

Main Rotor to Tail Rotor

18,732mm

Main Rotor Diameter

15,580mm

Overall Height

5,187mm

Weights:

Maximum Take-Off Weight

8,750kg

Minimum Operating Weight

5,730kg

Maximum Internal Fuel

1,469kg

Engines:

Powerplant

2 x Makila 1K2

Twin-Engine Take-Off Rating

2,243kW

Single-Engine, Super Continence

1,660kW

Performance:

Fast Cruise Speed

150kt

Maximum Sideways Speed

50kt

Maximum Rate of Climb, Twin-Engine Operation

2,620ft/min

Maximum Rate of Climb, Single-Engine Operation

1,280ft/min

Maximum Range, Internal Fuel

700km

Maximum Range, External Fuel

1,260km

Maximum Hover Ceiling (OGE) Out-of-Ground Effect

17,900ft

Maximum Hover Ceiling (IGE) In-Ground Effect

19,200ft

Excess Hover Power margin OGE, Sea-Level Anti-Tank Mission

39%

Weapons:

Missiles

8 or 16 anti-tank missiles, 7in SAL missile or HOT3
Air-to-air missiles, infrared guidance

Rockets

38 or 76 70mm unguided rockets, variation of warheads

Cannon

20mm F2 cannon, high-velocity ammunition (900 rounds)

Sighting Systems

Dual Helmet-Mounted Sight and Display (HMSD)
Stabilised nose-mounted sight with FLIR, TV, laser rangefinder, laser designator and autotracking

Avionics

Total mission modes
Target acquisition
Flight control
Health and usage monitoring
Communications
Threat detection and control
Flight and fuel

2.Introductions:

The Rooivalk is a latest-generation attack helicopter from Denel Aviation of South Africa. The South African Air Force ordered 12 Rooivalk AH-2As, the first of which entered service in July 1999. The helicopters form part of No. 16 Squadron at Bloemspruit Air Force Base (near Bloemfontein).

The helicopters have been delivered and were to be fitted with the Mokopa ZT-6 anti-tank missile. A production order for the Mokopa was placed in March 2004. Delays with the development of the missile mean that it is unlikely to be integrated on the Rooivalk.

The helicopter is planned to achieve initial operational capability in late 2009 but full capability with an anti-tank missile is not currently planned.

Rooivalk cockpit

The cockpits are in stepped tandem configuration. The weapon systems officer (WSO) is seated in the front cockpit and the pilot is seated in the cockpit above and behind the WSO. The cockpits, which are fitted with crashworthy seats and are armour-protected, are equipped with hands-on collective And stick (HOCAS) controls.

A Thales Avionics TopOwl helmet-mounted sight display (HMSD) provides the crew with a head-up display of information for nap-of-the-earth flight (NOE). TopOwl incorporates an integrated measurement system for directing an articulated weapon such as the cannon, or air-to-air missile seeker heads. It has an integrated Gen IV image intensifier and FLIR capability and provides transition from day to night use at the push of a button.

The Rooivalk has a crash-resistant structure and is designed for stealth with low radar, visual, infrared and acoustic signatures.

Weapons

The Rooivalk carries a comprehensive range of weaponry selected for the mission requirement, ranging from anti-armour and anti-helicopter missions to ground suppression and ferry missions. The aircraft can engage multiple targets at short and long range, utilising the nose-mounted cannon and a range of underwing-mounted munitions.

The 20mm, F2 dual-feed, gas-operated cannon fires high-speed (1,100m/s) ammunition at a firing rate of 740 rounds a minute. Two ammunition bins hold up to 700 rounds of ready-to-fire ammunition. The slew rate of the cannon is 90° a second. The cannon is chin-mounted on the helicopter.

The Rooivalk was to be armed with the Mokopa long-range anti-armour missile developed by the Kentron Division of Denel. Mokopa has a semi-active laser seeker head and is equipped with a tandem warhead. Range is over 8.5km. Rooivalk can also fire Hellfire or HOT 3 missiles.

“The Rooivalk is armed with the Mokopa long-range anti-armour missile.”

Rooivalk can carry four air-to-air missiles such as the Denel Aerospace Systems V3C Darter or MBDA (formerly Matra BAe Dynamics) Mistral.

The V3C Darter has an infrared seeker and a helmet-mounted sight for target designation. The Mistral, which has been selected by the South African Air Force, has an infrared seeker and range of up to 6km.

Rooivalk is equipped to fire 70mm folding-fin aerial rockets (FFAR), from the company Forges de Zeebrugge of Belgium, with a range of warheads, selectable according to the type of targets being engaged.

Countermeasures

The Rooivalk’s electronic warfare suite is the fully integrated helicopter electronic warfare self-protection suite (HEWSPS), incorporating radar warning, laser warning and countermeasures dispensing system. The system is flight-line programmable and in-flight adaptable to match the threat library with the mission’s area of operation.

The radar warner features low-effective radiated power (ERP) / pulse Doppler radar detection beyond radar detection range, ultra broadband frequency coverage, high pulse density handling and internal instantaneous frequency measurement.

The laser warner provides broadband laser frequency coverage to detect and display rangefinding, designating and missile guidance laser threats.

The countermeasures dispensing system, which is operated in manual, semi-automatic or fully automatic mode, is charged with chaff and flare cartridges.

Fire control and observation

Target detection, acquisition and tracking are carried out using the nose-mounted stabilised sight, TDATS. The TDATS sight is equipped with a low-level television sensor, Forward-looking infrared (FLIR), autotracker, laser rangefinder and laser designator.

“The Rooivalk has a crash-resistant structure.”

Navigation and communications

The Rooivalk is equipped with an advanced navigation suite including Doppler radar velocity sensor, Thales Avionics eight-channel global positioning system, heading sensor unit and an air data unit.

The communications suite consists of two VHF/UHF transceivers with FM, AM and digital speech processing, one HF radio with frequency hopping and secure voice and data channels, and an IFF transponder.


source: WILI PHIEU