波音737飞机关于油门杆活动线束断裂导致自动油门故障的说明

HNAT737技术问题说明提示单编号撰写校对批准/旧期T1P737-2021-22-007赵金良许敬远曾品2021.07.19标题关于油门杆活动线束断裂导致自动油门故障的说明一、适用性737NG二、背景描述机队曾出现数起起飞阶段按压TO/GA电门间歇性无反应或者AT间歇性自动脱开故障，最终排故确认均是由油门杆底座附近线束中导线断裂所导致的故障，咨询波音也接到过类似故障的案例，本文对此故障做出以下说明。三、解释说明1、实物情况左右侧油门杆上各有一个A/T脱开电门(S113/S114)和一个T0/GA电门(S786/S787),AT电门有衔接保持和断开复位两个通道，TOGA电门有A和B两个通道，每个通道的两根导线用黄色热缩管缩在一起，线束沿油门杆下行，先经过并固定在油门杆底部四分之一圆弧凹槽，然后左侧油门杆的线束从左侧结构框穿过，右侧油门杆的线束从右侧结构框穿过，向前绕大约四分之一圆弧后用卡子固定在结构框上。因此，从油门杆底端到固定卡子这部分导线会随着油门杆前后移动而活动，同时这部分线束上安装了透明的防磨套。图1.右侧油门杆线束走向2、导线断裂的原因对于该处导线断裂的原因，波音认为可能与油门杆移动过程中线束反复承受较大拉力及磨损有关。Response to Q1:Intermittent open circuit wiring located near the base of the throttle level in the quadrant canbe caused by high tension in the wire loom and can also occur if the wiring is rubbing against the quadranthousing,causing chaffing to occur on the sleeve of the wire loom.Over a long period of time,the wiringcontinues to rub against the quadrant housing,causing more chaffing to occur until the wire breaks (opencircuit)eventually.If the wire loom can be lengthened a little bit and/or routed such that it avoids makingcontact with nearby structure,that would help prevent this condition from developing in the future.The wiresthat are susceptible to this condition are:1/4