The blades on the 2nd stage compressor of one kind of aeroengine are frequently damaged components.Recently a fault of blade body fracture happened

which is different from the usual blade corner fracture.Judging from the shape of the fractured blade

it is a new type of fault

which is different from the corner fracture caused by the 2nd twist vibration.The fatigue started from the upper middle of the blade.The resulted crack expanded vertically up and down

and then turned horizontally in different directions.Finally

the upper part of the blade flew away.The flown part is about one third of the whole blade and the fracture shape is of "S" form.This paper provides an analytical conclusion drawn from the research work including:metallographic analysis of the blade fracture

scanning electron microscope analysis

computation and analysis of the vibration characteristics

the measurement of the static frequency and vibration mode of the blade

the test of fatigue breach

the measurement of the 10th relative vibration stress

and estimating of the fatigue life-time of the blade.The paper concludes that the mechanism of this new type fault is the 10th vibration of the blade

which occurred at 0 8 rating rotation of the aeroengine and the basic cause is the resonance and the flaw of the blade basin surface.