The failure of the root of the elbow tube in the hydraulic tube system of a certain type of aircraft was studied.First,according to the location of the tube and the fracture morphology,the tube’s rapid fatigue fracture failure was due to excessive bending stress and wearing of the flat nozzle.Then,through the modal analysis,it was found that the bending mode of the elbow tube coincided with the driving frequency band of the engine,a resonant mode which mainly for horizontal bending was expressed,resulting a large bending stress,which caused the wall to wear and matched with the fault.Thirdly,three improvements were proposed:adjusting the position of the floating clamp,reducing the initial installation stress and reducing the length of the elbow tube.The improved direction was determined after the simulation analysis and comprehensive comparison.Finally,based on the strain measurement method and engine test,the feasibility and validity of the improvement direction were verified by the test data.