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RAF Chinook

RAF Chinook

U.S. Army Chinook loads a howitzer gun.
Description
Role Medium transport helicopter
Crew 3 (pilot, copilot, crew chief/combat commander)
First Flight September 21, 1961
Entered Service (RAF) December 1980
Manufacturer Boeing Integrated Defense Systems
Dimensions
Length 98 ft 9 in 30.1 m
Rotor Diameter 60 ft 18.29 in m
Height 18 ft 8 in 5.7 m
Weights
Empty 22,450 lb 10,185 kg
Loaded 26,680 lb 12,100 kg
Maximum Takeoff 50,000 lb 22,680 kg
Capacity 44 troops or 24 litters and 2 attendants
Powerplant
Engines 2 Avco Lycoming T55-L-712 turboshafts
Power 2 x 3,750 hp kW
Performance
Maximum Speed 183 mph 295 km/h
Combat Range miles km
Ferry Range 1,280 miles 2,060 km
Service Ceiling 8,500 ft 2,590 m
Rate of Climb 1,980 ft/min 605 m/min
Thrust/Weight
Power/Mass hp/lb kW/kg
Avionics
Avionics
Armament
Guns 2 x M-134 miniguns and 1 x M-60 machine gun
Bombs
Missiles
Rockets
Other

The Royal Air Force is the second largest operator of the Boeing CH-47 Chinook of the 16 nations which use the type.

RAF Chinook's have been widely deployed; serving in the Falklands War, Operation Desert Storm, large peace-keeping commitments in the Balkans, the evacuation of Sierra Leone, Afghanistan and the 2003 Iraq War. The RAF's Chinooks force also provides more routine support of the British Military, particularly in Northern Ireland. One Chinook is maintained as part of the Falklands Garrison.

Contents

HC.1

The Chinook CH-47A entered service with the US Army in 1962. Following the unsuccessful Bristol Belvedere project, a similar design to the Boeing helicopter, the RAF ordered 33 Chinook HC.1s in 1978. These aircraft were comparable to the CH-47C, fitted with Lycoming T55-L-11E engines. 8 more HC.1s were delivered from 1984 to 1986 with the CH-47D's Lycoming T55-L-712 turboshafts.

The replacement of the HC.1's metal rotor blades with glass fibre rotors saw these aircraft designated HC.1Bs. The main cargo of the merchant ship Atlantic Conveyor, which was sunk during the Falklands War, was three Chinook HC.1s and five Wessex helicopters. One Argentine CH-47C was captured during the war and returned to RAF service as a HC2.

HC.2

The US Army's next generation Chinook, the CH-47D, entered service in 1982. Improvements from the CH-47C included upgraded engines, fiberglass rotor blades, a redesigned cockpit to reduce pilot workload, redundant and improved electrical systems, an advanced flight control system (FCS) and improved avionics. The RAF returned their original HC.1s to Boeing for remanufacture to CH-47D standard, the first of which returned to the UK in 1993. Three additional HC.2s were ordered with delivery beginning in 1995.

A RAF HC.2 crashed into the Mull of Kintyre on June 2, 1994 while carrying 25 senior members of the British security forces (RUC, Army and MI5) from RAF Aldergrove, near Belfast to Inverness, Scotland. In 1995 an RAF board of inquiry found that there was no conclusive evidence to determine the cause of the crash. However two air marshals, on reviewing the evidence, found the two pilots guilt of gross negligence.

This ruling has proved highly controversial, a subsequent fatal accident inquiry, House of Commons Defence Committee report and Commons Public Accounts Committee have all either left open the question of blame or challenged the original conclusion. Computer Weekly and Britain's Channel 4 News have suggested that the FADEC software was responsible for the crash. FADEC was the cause of an incident in 1989 and its caused a delay in the entry into service of the HC2. The Ministry of Defence successfully argued with Textron Lycoming, the FADEC and engine producer, that it was the engine and not RAF procedure which caused the 1989 crash.

6 further Chinooks were ordered in 1995 as HC.2As. The main difference in these and the standard HC.2 was the strengthening of the front fuselage to allow the fitting of a aerial refueling probe in future.

HC.3

Ordered at the same time as the HC.2As, 8 Chinook HC.3s were to enter service as dedicated Special Forces helicopters. These were to effectively be low-cost variants of the US Army's SF Chinook, the MH-47G. The upgrade would include improved range, night vision sensors and navigation capability. The eight aircraft were to cost £259 million and the forecast In-Service Date (ISD) was November 1998 (defined as delivery of the first six aircraft). As work proceeded, it became evident that displays for the weather radar and other systems anticipated for an avionics upgrade programme (put to contract in 1997) would not fit inside the existing cockpit.

One potential solution was to adopt a fully digital cockpit, as used by Chinooks purchased by the Royal Netherlands Air Force. However, this was not affordable within the funding available for the HC3 programme, and a hybrid solution was adopted, incorporating elements of the existing analogue cockpit and the new digital systems and displays. In March 1998 the new ISD was set at January 2002.

The problem seems to have been a lack of definition of requirements by the Ministry of Defence. Of 100 separate requirements only 30 were defined in the contract. All the aircraft were accepted from Boeing by December 2001, meeting, and in some cases exceeding, the contract. But none have so far been accepted into service. A key issue is that the Chinook HC3's unique, hybrid digital/analogue cockpit is reliant on software to operate. However, the contract did not specify that software documentation and codes should be analysed in accordance with UK standards in order to demonstrate the integrity of the software. It has not, therefore, been possible to demonstrate that the flight instruments meet these standards. The idea that the systems would be proved by the RNAF aircraft proved unfounded due to the unique configuration of the HC3.

One of the main contractors for the avionics system has recently indicated that it would allow access to some software data. However, the process of analysis is time consuming and expensive and, in addition, there is no guarantee of a successful outcome because the legacy software is not amenable to the techniques required to confirm the robustness of software design. Consequently, the Chinook HC3 is currently restricted to day/night flying above 500 feet in clear weather, and where the pilot can fly the aircraft solely using external reference points without relying on the flight displays. These restrictions mean that the helicopters cannot be used other than for limited flight trials.

Another problem is the corrosion allegedly suffered during the helicopters storage at Boeing. It was reported in 2003 that the US Army were interested in buying the 8 HC.3s, allowing the RAF to purchase MH-47Gs. However following inspection of the aircraft the US Army declined this option. One HC.3 was damaged during delivery, rolling backwards into a crane at Bristol docks on July 20 2001. Damage was significant but repairable. If and when the HC.3s enter service they will join 7 Squadron at RAF Odiham.

Chinook squadrons

Sources

  • HC.3 information edited version of NAO: Battlefield Helicopters
    "All material may be downloaded, copied or reproduced free of charge in any format or medium without requiring specific permission."
Last updated: 05-23-2005 13:53:41