波音737飞机关于FMV、VBV和FMV组合代码的排故原因说明

HNAT737技术问题说明提示单编号撰写校对批准/日期T1P737-2020-73-005赵斌符方洲曾品/2020.5.8标题关于FMW、VBV和FMW组合代码的排故原因说明一、适用性737NG二、背景描述在发动机自检时，遇到过FMV、VBV和FMV组合代码，在此对组合代码的成因进行简要分析。以便大家对此类型的发动机组合代码排故方向有更清晰的认识。三、解释说明1,手册说明FMV/VBV/FMV组合代码（另外FMV/HPTACCV/TRR也是一个组合），在FM73-25TASK故障解析中提到了下列内容：(3)Full Authority Digital Engine Control (FADEC)2;Channel A and Channel B;(a)Also,because the Channel A excitation circuit for the FMV position Linear Variable DifferentialTransducer (LVDT),High Pressure Turbine Active Clearance Control (HPTACC)position LVDT andthe Thrust Reverser Right (TRR)position LVDT are from a common source in the EEC,a short in oneof the three excitation circuits can set Channel A fault messages for all three systems.(b)Also,because the Channel B excitation circuit for the FMV position LVDT,HPTACC positionLVDT and the Thrust Reverser Left (TRL)position LVDT are from a common source in the EEC,ashort in one of the three excitation circuits can set Channel B fault messages for all three systems.(4)FADEC 3;Channel A and Channel B:Also,because the Channel A and Channel B excitation circuit for the Variable Stator Vane (VSV)position LVDT,the Variable Bleed Valve (VBV)position LVDT and the FMV position LVDT are from acommon source in the EEC,a short in one of the three excitation circuits can set Channel A or ChannelB fault messages for all three systems.从以上内容不难看出其实这些组合中的部件LVDT传感器，励磁电路都是来源于EEC的同一个激励源。那么实际上就有部件均真实不到位和激励源存在问题两种可能性方向。2,原理说明FMV/HPTACC/TR的LVDT励磁电压源、VSV/VBV/FMV的励磁电压源分别从EE的两个源头取电，示意图如下：SUPPLY是取电部分1/3