Q&A:起飞后起落架手柄不能收上检查单为什么有要求不能收起落架?

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回答一个问题：

Q









有这个关于起落架问题想咨询你，就是起飞后起落架手柄不能提到UP位。如果是空地电门故障故障了，检查单中就要求一直放下起落架去就近合适机场落地。

如果此时我遇到一些紧急情况，比如空速不可靠，记忆项目需要收上起落架来执行10/80或4/75的记忆项目。再或者就是有越障风险，比如单发情况下，我需要收上起落架来增加飞机越障余度。此时我违背检查单也要超控将起落架收上，会对起落架有损害吗？特别对起落架的放下有影响吗？如果能收上，，放不下来就惨了。






A

不建议收。QRH估计这里有考虑可能是起落架减震支柱卡在压缩位导致起落架空地信号异常或地面扰流板内锁活门没有关闭，起落架卡在压缩状态收起落架会导致起落架和机身结构损伤。



这个其实在检查单里能隐约看出来，关键是不要被表面现象迷惑，要分析造成这种现象背后的真正故障：



在检查单这里，并没有让机组继续去判断到底是空/地系统1失效还是地面扰流板连锁活门没有关闭导致的起落架手柄不能解锁，因为两者中的任何一个都可能是起落架卡在压缩位导致的。





两者导致收襟翼后出现起飞警告的原因：





并且空地信号在地面与内锁活门不在关闭位的故障现象也是不一样的，那么QRH为什么就没有进一步来判断呢？

如果我们分析两者的共同点，就不难发现，起落架空地信号和内锁活门位置控制都与减震支柱伸出还是压缩有关。



▲地面扰流板内锁活门开关控制钢索（推拉钢索），位于右主起上



当起落架处于压缩状态时，推拉钢索打开内锁活门，这样就能允许液压A系统压力去作动地面扰流板。当起落架处于伸出状态时，推拉钢索关闭内锁活门，不让液压压力通过，此时操作减速板时，地面扰流板不会作动。

后面咨询了厂家，QRH也确实是这样考虑的。

A.1

If the landing gear lever will not move beyond OFF to UP after takeoff, the Landing Gear Lever Will Not Move Up After Takeoff NNC (attached) must be performed before a decision is made to retract the landing gear. Pulling the landing gear override trigger and raising the landing gear without guidance from the NNC may result in damage to the landing gear and airframe, in-flight ground spoiler deployment, illumination of the TAKEOFF CONFIG warning light, sounding of the cabin altitude/configuration warning horn, failure of the cabin to pressurize and improper autobrake operation.

If a main landing gear leg remains compressed after becoming airborne, which would result in the Air/Ground system sensing an on ground condition, airframe and landing gear damage may result from the compressed landing gear leg retracting into the airplane structure.If the ground spoiler interlock valve remains open in flight due to a failure or because the right main landing gear is compressed, there is a risk of in-flight deployment of the ground spoilers. Air/Ground system sensing an on ground condition in flight may result in airborne illumination of the TAKEOFF CONFIG warning light, sounding of the configuration warning horn, failure of the cabin to pressurize and the AUTO BRAKE DISARM indication.

The Landing Gear Lever Will Not Move Up After Takeoff NNC mitigates all of these system effects, provided that landing gear is not retracted unless directed in step 4.

A.2

The flight crew must be aware that checklists cannot be created for all conceivable situations and are not intended to replace good judgment. In some situations, at the captain's discretion, deviation from a checklist can be needed. If performance were to require landing gear retraction contrary to the Landing Gear Lever Will Not Move Up After Takeoff NNC, the crew must be aware of the possible consequences described in answer 1 above.

所以这里并不建议机组去收起落架，除非实在是不收就要撞上了。

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