某型航空发动机试车后故障荧光渗透检测时，发现某级涡轮叶片存在线性显示。为了确定该线性显示的形成原因，对显示部位进行剖切及理化检测分析后确定：该线性显示为热裂纹，裂纹产生于铸造过程，且在试车过程中未出现扩展。结合该结论，针对涡轮叶片在制造阶段X射线检测工序和荧光渗透检测工序没有检出裂纹及裂纹形成的原因进行了分析，制订了相应的铸造工艺和无损检测工艺改进措施。

During the fault detection after the test run of an aero-engine, the linear indication of a stage turbine blade was found by fluorescent penetrate testing. In order to determine the formation reason of the linear indication, the indication area was cut and it can be determined by physical and chemical analysis that the linear indication was a hot crack, which was generated in the casting process and did not expand during the test run. Combined with this conclusion, the reason was analyzed why crack was not detected in the X-ray inspection process and fluorescent penetrate testing process in the manufacturing stage of turbine blades and the reasons for the formation of cracks. Corresponding improvement measures for casting process and nondestructive testing process were formulated.