在某型机大修后外场的例行检查过程中，发现外置机匣接耳存在涡流检测信号异常，着色检测无相关显示的问题。针对该疑似裂纹信号，借助荧光检测和数字射线实时成像等无损检测方法进行分析和探讨，并进行热处理去应力试验和微观观察，结果说明疑似裂纹信号源于试件表面或近表面的微裂纹，与可能存在的试件内部应力，以及近表面夹杂、气孔等体积型缺陷无关。表明涡流检测技术对试件表面或近表面微小裂纹具有很高的检测灵敏度和可靠性。

During routine field inspection after overhaul of a certain type of aircraft, it was found that the eddy current flaw detection signal of the outer casing attaching lugs was abnormal, and there was no problem of relevant display in coloring flaw detection.Aiming at the suspected crack signal, the nondestructive testing methods such as fluorescence flaw detection and real-time digital radiography are further analyzed and discussed, and the stress-relief experiment and microscopic observation of heat treatment are carried out, and the final results show that the signal of suspected crack originates from the micro-cracks on or near the surface of the specimen, which is independent of the volume defects such as internal stress, near-surface inclusions and pore.Eddy current testing has high sensitivity and reliability for detecting micro-cracks on or near the surface of specimens.