PPRuNe Forums - View Single Post - B738 Air Systems (Recirculation fans, Temperature control, Press controller)

20th Jan 2012, 08:12

#3 (permalink)

unintentionallyblank

Join Date: Nov 2007

Location: Up the mountainside, far above the clouds

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Thanks for your answer.

What confuses me is that the recirc fans do not have an on-mode, only AUTO and OFF, and quoting the FCOM (my emphasis):

Quote:

AUTO –
• in-flight–

• the left recirculation fan operates if both packs are operating unless either PACK switch is in HIGH
• the right recirculation fan operates if both packs are operating unless both PACK switches are in HIGH.

• on the ground–

• the left recirculation fan operates unless both PACK switches are in
HIGH
• the right recirculation fan operates even if both PACK switches are in
HIGH.

It does not specify any condition where the fan will be operating unless both packs are operating. (Except on the ground, where it makes no mention of it.)

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