他山之石 – 第 121 页

液压油渗漏提升方案

SE-27-21-35509

有航司航前检查发现主轮舱内P/N 272A4453-76的液压管有个小孔漏油，原因与刀型封严保持座出现干涉，更换管路行，在事件被发现前没有异常的液压油勤务。也就是此类渗漏较难提前发现。

该航司为缓解液压油渗漏导致的延误取消事件，开展了液压系统渗漏检查和力矩检查工作，分析显示，对于老龄飞机的液压油渗漏事件有逐步增长的下降趋势，过去两年共142起，TOP问题有接头/管路松动（8），B螺帽裂纹（21），O型封圈（4），泵（28），其它（85），疫情停场后没有出现重大问题。

封存的737MAX机队出现大量的发动机进气道唇口腐蚀问题，根据SRM进行腐蚀清除，根据AMM封存程序对唇口进行保护，根据SL涂抹AECI3保护涂层，但在封存定期检查中，仍然能观察到点状腐蚀反复发生，封存地点位于迪拜，不算太潮湿，湿度在40%~60%之间，在同样环境封存的737NG就没有类似报告。航司认为唇口蒙皮材料的设计和规格上有差异，MAX采用的是2219-T42铝合金板材单片结构，NG采用的是三段式2219-O铝板，热处理至T62，所用材料热处理等级不同，航司已经投入大量资源来处理唇口反复腐蚀问题。

大风和沙尘天气特检的执行

每年春季大风和沙尘天气都会把特检工卡重新撸一遍，主要在于各航司解读。在2019年编写了SOP并获得各航司邮件批复后，这个疑问少了很多，但还是有相关疑问。整合疑问和波音的答复，有以下要点。

1，到底什么情况下需要执行特检 4-4417619877

The subject AMM conditional inspection is subjective. It is the operator’s responsibility to determine if the inspection is necessary when or after the aircraft has been exposed to the subject conditions.

2, 做什么样检查深度 3-3277500197

Boeing recommends that operators use their past experience to guide them in deciding whether or not an inspection is necessary, and the level of the inspections that are necessary. Boeings Extreme Dust/Sand Conditional Inspection criteria is a guide for operators to use when there are reports of sand intrusion and or extreme dust deposits on airplanes due to a wind storm. When operators are using Boeings Extreme Dust/Sand Conditional Inspection procedure and the careful documentation of the outcome can be used to further establish a baseline of Hainan Airlines own inspection.

3，停放的飞机需不需要做 3-4335252938

The dirt environments are areas with extreme dust or sand condition. Please note, that datum AMM Section 05-51-27/201 is written for cases where it was confirmed that the airplane was exposed directly to sand/dust during sand or dust storms. In general we recommend that operators use their past experience to guide them in deciding whether or not an inspection is necessary, and the level of the inspections that are necessary. If the environmental event is sufficient to create the possibility that static ports, pitot tubes, or other locations listed in the conditional extreme dust/sand inspection procedure to be reported to have deposits of fine-grained calcareous silt or clay material, then Boeing recommends performing the conditional inspections. Please note, that subject procedure is also applicable to parked airplanes, which were affected by the sand storm. Intervals provided in the SUBTASK 05-51-27-200-004 are flight hours.

4，钢索发现扬尘后的检查 4-4338594668

Boeing Service Request System We recommend cleaning and relubricating the cables, pulleys and any operating mechanisms affected. HNA may wish to inspect the control cables after approximately 3 months and 6 months to ensure no further damage has occurred to the control cables. Exposure to dust and/or sand will cause contaminants to accumulate on the control cable grease. If not cleaned, this can lead to shortened cable life as wells as higher control forces and sluggish operation of the associated flight control system.

5，经历沙尘后的建议 3-3277500197

Because dust and sand are inert particles, they will not cause harm to exterior fuselage/wing structure/airplane skin. Boeing recommends removing the dust/sand as soon as possible so that it does not get ingested into the engines, the air distribution system, or other internal areas of the aircraft. Dust/sand that blows through the area may also contain contaminants that can lead to premature corrosion of certain areas if those contaminants are not removed promptly.

VSV作动筒安装衬套磨损

自有案例。

运行中常在更换VSV作动器的时候，发现衬套磨损的情况，有几个件是常磨的，特对功用和材料做一解释。

实际上，VSV作动筒和曲柄组件的衬套材料为两种，一种是Inconel718（含铌、钼的沉淀硬化型镍铬铁合金），一种是填充了石墨的聚酰亚胺，其中有石墨的衬套为EIPC的280/290，是专门用于磨损，可以保护270（link）,作动筒杆端和曲柄组件孔，这种衬套发料也较多；其它衬套是镍铬铁合金，这种材料具有高的抗拉强度、疲劳强度、抗蠕变强度和断裂强度，尽管强度高，但在VSV作动筒作动时，这些衬套多少会受到往复冲击力，使得其防旋转表面和周向贴合面都会有少许的磨损，类似下图实物所示；这类磨损标准可以在在发动机手册中获取到，并不在AMM中体现。但建议直接更换，否则还得安排持续监控和更换。所以非必要时不要考虑参考发动机手册保留使用。