Increasing life cycles and lowering costs with the new CFM56-7 When Boeing delivered the first of its new generation 737 family towards the end of 1997, the event also marked the entry into service of CFM International's latest CFM56-7 engine, bringing with it significant advances in operating and maintenance costs.

The new high bypass turbofan builds on existing CFM56 models, but incorporates a series of design innovations which add up to sizeable operating savings. Maintenance costs on the new engine have been brought down by 25% compared with its predecessors, thanks to more durable high temperature components. Specific fuel consumption has been cut and the exhaust gas temperature margin raised, to improve engine performance and durability.

The resulting engine, rated at 84-117kN (18,500-26,300lb), offers an overall improvement in time-on-wing of as much as 20%. The Awards judges were impressed with the work that CFMI has carried out to improve operating economics for its customers. As the sole powerplant offered on the new generation 737 the CFM56-7 is already part of the world's best ever selling engine/aircraft combination.

CFMI, the joint venture between General Electric and Snecma, worked closely with Boeing to help improve access for line maintenance and component replacement. Together they defined the engine's configuration and installation using digital mock-ups and solid modelling techniques.

The design also includes use of single crystal materials for high-pressure turbine blades and nozzle to improve durability, while the fan is 1,550mm in diameter for maximum specific flow, incorporating 22 solid titanium, wide-chord blades. The resulting 92% combustion efficiency is believed to be the best in the industry.

An optional double annual combustor, adapted from the CFM56-5B, is also offered on the new engine. The DAC will lower harmful nitrous oxide emissions by as much as 45%over the standard engine.

Source: Flight International