注意：确保单向活门已经安装，并且位置正确。

NOTE: Make sure that the check valve is installed and that it is in the correct position.

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从客舱再循环风扇（15）上拆下堵盖、从单向活门上拆下衬套。

Remove the blanking plugs from the cabin recirculation fan (15), the sleeve (1) and from the check valve (7).

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必须同时从飞机外部和飞机内部接近组件下游单向活门。建议由两个机械员来完成此程序。

Access to the pack downstream check-valves must be obtained from both outside and inside the aircraft. Two persons are recommended for this procedure.

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