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BOEING DEVELOPS NEW CHINOOK VARIANTS

By Karl Schwarz

If you walk through the hangars of Boeing in Philadelphia, you feel moved back in time by decades. The typical silhouette of the tandem rotor transport helicopter Chinook is being assembled inside and on the apron. This model dates back from 1962 and has hardly changed its shape in the meantime.

However, first impressions are deceiving. Since the YCH-47A took off on her maiden flight on 21 September 1961, the possible payload has more than doubled, the range has been improved significantly and so has the aircraft's reliability. The US Army and more than another dozen customers from all over the world would not want to do without their workhorse for heavy loads.

Boeing is currently working on improved versions of the CH-47 in order to guarantee continuing success for the Chinook. The new standard model intended for the international market is the CH-47SD ("Super D"), while the Improved Cargo Helicopter (CH-47F) is being developed for the US Army. Both models will ensure that the factory will be working to full capacity until 2015.

Foreign customers will get an even better deal as far as technology and performance is concerned. The CH-47SD incorporates all the improvements, which have been added for various customers. Among these are:

• increased take-off weight
• larger fuel capacity (7,827 instead of 3,914 litres). There is a fuel tank in each of the side fuselage fairings
• Honeywell-(AlliedSignal-)T55-L-714A-engines. They are rated at 4,075shp (3,039kW) and are 22 per cent more powerful in "hot and high" conditions (high temperatures, high altitudes) than previous aggregates. With Full Authority Digital Engine Control (FADEC) they are more responsive in all flight envelopes. The characteristic fuel consumption of these engines is three per cent better, and they need less maintenance.
• cockpit with colour liquid crystal displays and two input devices. Pilot and co-pilot have one monitor each for flight position and navigation display as well as one large multiple function display. System data is presented by two centrally placed monitors. Naturally flights with night vision goggles are also possible.
• improved avionics. The ACMS (Avionics Control and Management System) integrates instruments like two flight data computers, redundant digital GPS/INS naviagation, three axis auto pilot and radar altitude meter. Additional systems like a colour digital map, FLIR, field of vision instrument (HuD) and data loader or Health and Usage Monitoring (HUMS) can be adapted without any problems.
• longer nose for installation of weather radar
• improvement of the airframe in several areas. Some ribs are maschined from a single piece. This makes the cell more sturdy and durable. Another important effect is the reduction of vibrations in the cockpit area, which makes some dampers redundant.

Work on designing the CH-47SD started in 1997. However, Boeing announced the new model officially on 5 March 1998, after securing a contract with an "unnamed" customer (probably Signapore).

The "Super-D"-Chinook made her maiden flight on 15 August 1999. Jack Jordan and Armand Barreault were the test pilots on board, supported by Joe Schluck and John Williams. After an hour and a half in the air and another flight on the same day Jordan was very happy with the aircraft. By now deliveries have already started.

As well as Singapore, Taiwan has signed a contract for nine CH-47SD at the turn of the year. This contract is worth over $300m (DM580m) including spares and logistics. Boeing's fly-away-price for the Super-D is "less than $30m". Together with Greece's order of seven CH-47D, manufacturing is ensured until 2001. Turkey and some South East Asian countries have also expressed interest. Naturally Boeing is responding to the joint tender by Sweden, Norway, Finland and Denmark for a new multiple purpose helicopter.

Boeing is currently working on the first CH-47F for the army. The US Army has to make do until 2020 with this variation, which is derived from changing the existing CH-47D. By then there might be a Joint Transport Rotorcraft for all US Forces. Studies for a renewed Chinook modernisation program started after the Gulf War at the beginning of the 1990s. Because of lack of funds the army had to give up ambitious plans like the introduction of a four-bladed rotor and larger tanks. What remained was a leaner specification for the ICH (Improved Cargo Helicopter), which has the following main points:

• new cockpit instrumentation by Rockwell Collins. Boeing chose the company for this task in April 1998, yet already existing systems are used throughout. Pilot and co-pilot are each given three liquid crystal displays, however the engine instruments remain analogous.
• Mil-Std.-1553-data bus. Additionally there are systems like digital map generator, data loader and improved radio sets.
• strengthening of the airframe in order to decrease the level of vibration and reduce the risk of cracks, which may develop. The cockpit section is manufactured from scratch, since it is cheaper than labour intensive alterations.
• repair of airframe damage if required
• changes to the rear rotor mast, which will make it easier to dismantle the entire engine unit for air transport.

There are also improvements which are either already underway or planned for the entire Chernook fleet:

• installation of T55-GA-714A engines with higher output and lower operating costs. This means that existing -712 engines are being altered. The CH-47Ds have gradually been upgraded with these engines since 1999.
• new rotor head, in which elastomer bearings are being used, which make maintenance a lot easier. The number of parts is reduced by 60 per cent to about 120. To begin with there is a development program, which costs $23m. Great Britain is also involved in this.
• additional tanks in the cabin. Robertson Aviation is building an improved system, which comprises three containers (9,080 litres altogether). It can be used in all Chinooks after some small alterations have been carried out.

As a result of this the US Army will receive Chinooks which are suited to conditions on the battlefields of the 21st century: more exact navigation, improved communication, lower operating costs and the regaining of performance reserves are the most important points. The CH-47F should be able to transport an M198-Howitzer weighing 7,260kg over a distance of 90km even in poor climatic conditions. Boeing intends to show the abilities of the new Chinook versions in the summer of 2002 during field trials in Fort Campbell. For this purpose two CH-47Ds are currently being converted to the latest standard. They arrived in January 1999 in Philadelphia and were completely taken apart and inspected.

The CH-47F's maiden flight is planned for June 2001. The order for a preliminary series could be given as early as in December. Deliveries would start in March 2003. This would mean that the first squadron would be ready for action in September 2004. According to current plans the US Army intends to convert 302 of its CH-47D, a program, which would run until 2015.

The entire cost is estimated at about $3bn (DM5,8bn). It is probably not a bad investment, since the Chinook will not take her leave from the US Army before 2033. This would add up to 72 years since her maiden flight.

From page 50 of FLUG REVUE 3/2000