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Aviation History
1987
1987 - 0036.PDF
powers the airborne early warning Boeing E-3, its KE-3 tanker derivative, and the Boeing E-6 Tacamo submarine commu nications aircraft, for which applications 130 engines are on order. CFMI is anticipating competition for further KC-135R re-engining contracts from IAE with the V.2500, and is ready to respond by offering the more-fuel- efficient CFM56-5. General Electric expects the logistic advantages of staying with the -2 to weigh against a change of engines, however. The runaway success of Boeing's 737-300 has ensured the success of the CFM56 and guaranteed it a place in the propulsion hall of fame as the biggest civil engine programme of the 1980s. So far 1,435 CFM56-3s have been ordered, not only for the 737-300, but more recently for the stretched, 150-seat -400. Boeing's imminent launch of the short-body 737-1000 can only add to the success because the CFM56 is the only engine available on this range of airliners. Airbus is a new outlet for CFMI, but one the partners are pursuing with deter mination in the face of fierce competition from the five-nation, seven-company IAE consortium. The 25,0001b-thrust CFM56-5 is the A320 launch engine, and powered the European 150-seater on its February 22 first flight. Certification of the engine is scheduled for August, a year ahead of the competing V.2500, and so far some 170 -5s are on order to power A320s. The two engines are locked in a major battle to power the 150 A320s ordered by Northwest Airlines and the GPA leasing group. Recent experience suggests that CFMI has a tough fight on its hands, but IAE has encountered development setbacks with the V.2500, and CFM56 performance improvements are on offer to back up CFMI's arguments of greater reliability and lower maintenance costs. The CFM56 line has effectively split into two families. The original CFM56-2 combines a 68in-diameter Snecma fan with General Electric's F101 core. The 20,000-22,0001b-thrust CFM56-3 intro duces a 60in-diameter GE-designed fan, but the rest of the engine is unchanged and is interchangeable during production. For the latest 23,5001b-thrust -3C power ing Boeing's 737-400, CFMI has "tuned the airflow" through the engine, gaining a 2 per cent reduction in s.f.c. This tune-up will be available on CFM56-2 and -3 engines from 1988. The CFM56-5 is more than a tune-up: it is a major redesign retaining commonality in mechanical design with the -2/3 but with an all-new airflow path from the re-optimised 68in-diameter fan to the low- pressure turbine, incorporating tech nology from GE's larger CF6-80C2. The major feature is a GE/Snecma full- authority digital engine control (Fadec) system, which gives greater capacity for optimisation. The 25,0001b-thrust CFM56-5-A1 for the A320 is 11 per cent more fuel-efficient than the original -2 engine. For the long- range A340, and a possible stretched A320, CFMI has offered a 28,6001b-thrust CFM56-5-S2 with a 2 per cent lower s.f.c. Part of that improvement comes from the Production of the original CFM56-2 (F108) continues to re-engine US Air Force KC-135s long-duct mixed-flow nacelle, which makes sense on the long-range A340, says CFMI. The 28,6001b thrust rating was demonstrated by the first -5 to enter test. Advent of the 30,0001b-thrust IAE V.2500SF SuperFan, promising a 10 per cent s.f.c. reduction over the basic engine as an A340 powerplant, has prompted CFMI to study a 30,0001b-thrust CFM56-5. This is within the fan's capa bility, and will not require a major redesign, says CFMI, which is currently investigating the engine's ultimate limits. As well as the increased thrust, CFMI is offering a 3 per cent s.f.c. reduction, half of which Airbus is currently using in its A340 proposals to airlines. While CFMI has signed a memorandum of understanding with Airbus to certifi cate the 28,6001b-thrust CFM56-5 in 1990 to meet the A340's 1992 in-service dead line, that agreement has yet to be amended to cover the 30,0001b-thrust engine. There can be little doubt, however, that Airbus would like the extra thrust, and reduced fuel consumption, to compete more effectively with the McDonnell Douglas MD-11. Airbus says it has commitments from nine airlines for 104 A330/A340s, more than enough to launch development if financial backing is forthcoming, but it refuses to divulge what proportion are for the long-range four-engined A340 or which engines have been specified. The European consortium has confirmed, however, that while only SuperFan power is available on the 294-passenger A340-300, the CFM56 will be offered on the 262-seat A340-200 if CFMI can guarantee availability of the 30,0001b- thrust engine. According to Airbus figures, the CFM- powered A340-200 will fly 7,000 n.m., 700 n.m. less than the SuperFan-powered version, but the consortium admits that IAE's engine is significantly more expensive. CFMI will no doubt emphasise the proven reliability and maintainability of the CFM56 and make much of the fact that SuperFan has a gearbox between its V.2500 core and 107in-diameter variable- pitch fan. With Boeing considering stepping-up production of the 737-300/400, and General Electric and Snecma gearing up to build 50 CFM56s a month in response, CFMI is confident of meeting their target of 5,000 engines sold by 1992, despite the increasing competition. At that time Boeing will introduce its 150-seat 7J7, powered either by IAE's SuperFan or General Electric's open-rotor UDF. If the airlines choose UDF power, Snecma will take a 35 per cent share in development and production of the engine. O FLIGHT INTERNATIONAL, 4 April 1987
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