最近有人问到关于737NG新型电门式发动机起动手柄,误碰导致发动机空停的问题,在这里简单说一下吧。
旧件号的问题之前已经提过:
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之前老件号254A1221-7/-8的设计上有缺陷,电门提起后外筒能转动,如果不正确的操作导致电门外筒扭转,会使电门锁定功能失效。
厂家后面引入了新件号254A1221-13/-14,取消了锁片止挡设计,采用了止挡槽的设计,提高电门防扭转的能力,从源头上解决了这一风险。当前公司机队都已经换成了新件号。
但是,新件号254A1221-13/-14的起动手柄电门也存在一个问题,在之前的文章中也提到了:
新构型启动手柄254A1221-7和254A1221-13
就是起动手柄能够保持在CUT OFF和IDLE位之间的凸台上:
而此时与起动手柄相关的微动电门都已经到IDLE位了,所以此时发动机起动和运行都和正常的没有区别,但是由于没有进止挡槽,相当于电门处于提起状态,轻轻一碰电门就会移动。万一是往下碰的话,就会移动到CUTOFF位,相应发动机会关车。
10.1值班的时候,专门去找航材的备件254A1221-13试了一下,电门确实是能够不进卡槽,保持在CUTOFF与IDLE之前的中间位置,但是轻轻一碰就会移动到卡槽。
后来发现海航其实早就发现这个问题了:
以下图片和视频均来自 ISO-76-20-34129
From 2016, the new delivered aircrafts equiped with new model start level just like swtich. Recently, HNA met one case need to replace the start level pack, HNA fond there is some IFSD risk about the new spare(PN 254A1221-13). When move the switch from cutoff to idle, the swich can stop at the plate between IDLE and CUTOFF location as attachment photos show, we measured the resistance of the IDLE Micro switchs, the idle Micro switchs has closed, so this means the pilot can start the engine when the switch stop on the plate, if the pilot did not notice it, The pilot may accidentally touch the switch to the cutoff position. HNA looked for another 3 spares, they are same with the first one. HNA would like to ask if any other operators experienced the same situation or check your spares. Please post your experience if you have similar issue.
▲起动手柄电门没有进止挡槽
针对新构型电门式的起动手柄,存在未卡住导致误碰移动到CUTOFF位的空停风险,建议机组在每次启动好发动机后,往下扳一下电门,确保电门已经卡住不会动。
737NG 机组经典的手柄“三拍”检查:
当前针对新构型电门式的起动手柄的空停风险,也没有什么好办法避免,估计顶多也就是在FCOM加上确认起动手柄卡在IDLE位的步骤,还是老传统经验不能忘。
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