某型航空发动机在完成总运转时间2 081 h后进行拆解检查，在一件TC6钛合金高压压气机Ⅵ级转子叶片上发现沿叶片纵向分布有两条裂纹。通过宏观观察、断口分析、金相检验、能谱分析及硬度测试等方法对裂纹产生原因进行了分析。结果表明：该裂纹为试车过程中产生的疲劳裂纹。发动机在完成阶段性试车后进行拆解检查，复装后叶尖间隙不满足设计要求，导致在随后的试车过程中叶尖与机匣封严涂层发生严重刮擦，造成局部超温、掉块，形成疲劳裂纹源并最终扩展为裂纹。

A certain type of aero-engine was disassembled and inspected after 2 081 h of total running time. Two cracks along the blade longitudinal distribution were found on a TC6 titanium alloy high pressure compressor stage VI rotor blade. The causes of cracks were analyzed by means of macro observation, fracture analysis, metallographic examination, energy spectrum analysis and hardness test. The results show that the cracks were fatigue cracks produced during the test run. After the engine was disassembled and inspected after the stage test run, the clearance between the blade tip and the casing seal coating does not meet the design requirements, resulted in serious friction between the blade tip and the casing seal coating during the subsequent test run. It caused local over-temperature and block falling, formed fatigue crack source and finally expanded into cracks.