ENGINE CF34-8E Highly Recommended Service Bulletins Minimum Workscope CF34-8 Engine Shop Manual, applicable Aircraft Maintenance Manual and other CF34CF34-8 Technical Manual Index September 1, 2016 Following is the CF34-8 Component Maintenance Manual Section of the Technical Manual Index. The GE CF34 turbofan, developed from the GE TF34 used on the Republic A-10 and Lockheed S-3, is an efficient and quiet engine that has a 6.2:1 bypass ratio.