某型通用飞机在定期检查中发现固定刹车扭力板的自锁螺母腐蚀严重，且有少量的螺母完全断裂，导致与之相连的螺栓出现松动。根据同型飞机在5个机场运行环境中该型螺母状态的统计分析，选取了10件样品进行了研究。采用3D光学显微镜、扫描电镜（SEM）和能谱仪（EDS），对腐蚀螺母的宏观、微观形貌进行观察，对螺母外表面和断裂横截面的元素进行对比，并根据镀层特性和运行环境，分析了该型螺母腐蚀的原因。结果表明：恶劣的外部环境、实际运行条件和人员操作方式造成了螺母表面镀层的损伤，镀层的损伤是刹车区域该型螺母腐蚀的主要原因，地区酸雨和潮湿环境加剧了螺母的腐蚀；镀层的损伤和长时间腐蚀造成螺母的失厚率较大。

In the periodic inspection of a type of general aircraft, it was found that the self-locking nuts of the fixed brake torsion plate were seriously corroded, and a small number of nuts were completely broken, resulting in the loosening of the bolts connected to them. According to the statistical analysis of the nut status of the same type of aircraft in five airport operating environments, 10 samples were selected for research. The macro and micro morphology of the corroded nuts were observed by 3D optical microscope and scanning electron microscope (SEM). The elements of the outer surface and the fracture cross section of the nuts were compared by energy dispersive spectrometer (EDS). According to the coating characteristics and operating environment, the causes of corrosion of this type of nuts were analyzed. The results showed that the harsh external environment, actual operating conditions and personnel operation mode caused the damage of the coating on the nut surface. The damage of the coating was the main reason for the corrosion of the nut in the brake area. The acid rain and humid environment aggravated the corrosion of the nut. The damage and long-term corrosion of the coating caused a large thickness loss rate of the nut.