The CFM56-3 was designed for Boeing 737-300/-400/-500 series aircraft, with static thrust ratings from 18,500 to 23,500 lbf (82 kN to 105 kN). A cropped fan derivative of the -2, the -3 engine has a smaller 60in fan diameter and lower bypass ratio, but retains the original basic engine layout.
A significant challenge for this series was the size of the wing-mounted engine for ground clearance. This was partially overcome by mounting the accessories at the lower corners, and flattening the nacelle bottom and intake lip, thus giving a distinctive appearance of the Boeing 737 with CFM56 engines. The engines were also moved forward and raised, with the top nacelle surface essentially level with the upper surface of the wing, and tilted 5 degrees up. This not only helped increase the ground clearance but also directed the exhaust downwards which reduced the effects of pylon overheating and gave some vectored-thrust effect, assisting take-off performance.
It was first certified by the US Federal Aviation Administration in January 1984. It became the most numerous turbofan variant in aviation history with 3,975 engines produced for the 737-300/-400/-500. It is very reliable and has a high resale value.
Leading particulars for the -3B1 are bypass ratio 5.0, overall pressure ratio 27.5, airflow 655lb/s, static thrust 20000 lbf.