Re: Wing vs. tail-mounted engines?

Date:         09 Apr 2001 15:37:02 
From:         gbeaman@pei.sympatico.ca (Gord Beaman)
Organization: ISLAND TEL
References:   1 2 3 4
Followups:    1
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matt weber <mattheww@Qwest.net> wrote:
--cut--
>>
>>(I can't think of any case of failure of the wing box or root structure
>>causing an accident on a post-war commercial airliner -- can anyone?)
>That what caused the Two Electra accidents indirectly. The whirl mode
>failure of the engine mounts caused the wingbox loading to exeed the design
>limits, and the actual failure was the  wings came off the aircraft.  The
>fix was to stiffen the wing, and make the engine mounts stronger.

Bit more than that Matt,,,they discovered that the 'whirl mode'
problem was causing sympathetic vibration of certain stiffeners
and support structures in the wings and that the fix was to add
syncronization and syncrophasing of the propellers. This system
is now used on all twin and four engined a/c using Allison T-56
type engines. C-130, P-3, and Convair 580's are the types that I
know about, there's likely others. This system has the added
benefit of reducing crew fatigue due to less engine induced
vibration.