针对飞机液压导管的疲劳裂纹提出了一种超声表面波检测方法，根据裂纹形貌及导管端头的结构特点，设计制作了对比试样和频率为7.5 MHz的四通道表面波聚焦探头，匹配专用夹具工装和高信噪比的四通道探伤仪可实现长为3 mm，深为0.1 mm的平管嘴根部缺陷以及长为3 mm，深为0.14 mm的喇叭口根部缺陷的检测。该方法解决了导管内液压油、装配及遮挡等多种因素的干扰问题，达到了操作便捷和检测结果可靠的目的，满足了在役检测的需求，可为同类型薄壁导管的检测提供借鉴。

Surface acoustic wave testing was proposed for fatigue crack in aircraft hydraulic pipe. According to the crack morphology and the structural characteristics of pipe head, reference samples and four-channel surface wave focusing probes of 7. 5 MHz were designed and manufactured. After matching special fixture and four-channel instrument with high signal-to-noise, the root defect of smooth nozzle with length of 3 mm and depth of 0. 1 mm, and the root defect of bell mouth with length of 3 mm and depth of 0. 14 mm can be well detected. This method solves the interference of hydraulic oil, assembly and shielding in the pipe, realizes the purpose of convenient operation and reliable detection results, satisfies the requirements of in-service testing, which can provide reference for testing of the same type of thin-walled pipes.