PPRuNe Forums - View Single Post - Pneumatic noise in 737 cockpit below 4000'
Old 30th August 2014 | 09:41
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172_driver
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Joined: Jan 2006
: CPL
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From: Between a rock and a hard place
It's the overboard exhaust valve opening at low differential pressures (around 4000 ft) ditching air from the E&E bay straight out on the street. At higher differential pressures I believe this air leaves "the normal way" via the outflow valve.
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