The blade end-bend technique is applied to the first and second stators of the HP compressor of a twin-spool engine to ameliorate the flow on the second and third rotors. The tests of the modified engine show that its surge margin and efficiency are enhanced by 7.3 and 4.1 percent respectively

but the flow and pressure ratio vary only a little. The flight tests prove that the shutdown of the engine which occurred in flight has been eliminated

so that the engine can operate reliably and stably within the overall flight envelope

and the performances of the engine and the aircraft has been improved significantly.