Re: A320 and Noisy Hydraulic Pumps

From: (Steve Howie)
Organization: Aunt Sengas Mealie Puddin' Factory
Date:         09 Apr 95 22:37:12 
References:   1 2
Followups:    1 2 3
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George Hull ( wrote:
: In article <airliners.1995.347@ohare.Chicago.COM>,
: (Tony Heatwole) wrote:

: > I learned from talking to the captain after the flight that the sound
: > (which they couldn't hear in the cockpit) was the cycling of an electric
: > motor maintaining hydraulic pressure. Since they had to deploy the
: > flaps slightly for the de-icing operation and the engines were off,
: > they had get hydraulic pressure for the flaps from the motor. The
: > captain noted that DC10s, especially, have a reputation for noisy
: > hydraulic pumps.

I'll add the 767 to the list with noisy pumps. I was seated about halfway
down, aisle seat in the middle row on an Air Canada flight from SFO to
YYZ.  When we were on our descent to Toronto, the hydraulic pumps would
make a low-pitched but LOUD "ZZZZSSSSHHHHHH" noise when we were
manuevering, seemingly only when we were banking. When the flaps were
extended for landing, a much higher-pitched, but quieter pump seemed to be
working. Are there different pumps for different control surfaces??

Steve Howie				Email:
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