Loss of Engine Cowling
I understand that the falling object may have been an Engine Cowling? There have been numurous incidents caused by aircraft taking off with the engine cowlings unlatched after maintenance. More recently this has been a problem with the A320 (V2500) where the unlatched catches are difficult to see as the engines are so low down. I do not know the cowling arrangements on a B707 and whether an unlatched cowl is easily spotted. But the results can be dramatic - severe pylon damage; tailplane damage, fusalage damage (I recall a passenger window being broken on an A320); the engine itself severly damaged e.g. fuel pipe rupture, engine controls jammed etc; and flap damage.
How easy is it to leave the cowlings unlatched and undetected on a B707 - I suspect someone out there will know! But I am not aware of such an incident causing an aircraft to crash.
Just a thought.
bizdev