Re: 747 vibration

From:         Tony Maddern <>
Organization: University of New South Wales
Date:         03 Sep 96 01:16:58 
References:   1
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> John Maddaus asked two questions about airframe vibration in B747-400s and an unexpected violent jolt on climb.

I often experienced airframe vibration in the -400 on intial climbout
during flap retraction. We investigated whether or not it was flap
assymetry causing disturbed airflow over the tail or if it was a wheel
vibration coming through the hull. Boeing assisted in the investigation
but we never came up with a satisfactory explanation.

The 'severe jolt' sounds like wake turbulence when you flew across the
wake of another aircraft. Although wake turbulence is normally
associated with take-off or approach and landing it can be experienced
at any altitude. At altitude it is normally experienced as a very short
violent jolt because the aircraft transits the area of wake turbulence
so quickly.

Rgds, Tony Maddern (ex 747-400 driver )