Date: 09 Apr 2001 15:37:02 From: email@example.com (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.