在尝试循环起落架手柄后，如果不成功，则 L/G : KEEP DOWN。我之前以为是要再把轮放下，但又没有 “L/G LEVER ... DOWN”的动作。
空客回复才让我发现自己理解错了，这个故障可能只是某个起落架没收上，而不是全部起落架。所以这句话只是说“保持收不上的起落架在放下位”，手柄还是在收上位的，而不是要把其他起落架也放下。
具体请参考 TechRequest 原文：
Q: L/G RETRACTION FAULT
Why there's no L/G LEVER DOWN if recycling is not successful? According to the procedure, we just L/G: KEEP DOWN with the lever up after recycling.
A:
IF RECYCLE NOT SUCCESSFUL OR AFTER 50 seconds, ECAM requests; L/G KEEP DOWN, this is done by selecting the L/G Lever DOWN.
Q_2:
“IF RECYCLE NOT SUCCESSFUL OR AFTER 50 seconds”，the lever is up and the L/G are still down. So we already KEEP DOWN them. There's no action line requiring crew to select lever down again, that's a risk.
A_2:
The purpose of keeping the L/G LEVER UP is to set all the operational landing gears in the retracted position. In this configuration, only the defective gear(s) will remain down during the rest of the flight (limiting the risks of operational disturbance or mechanical damages).
