megan: "From information provided I calculate the point of wing tip contact is some 14 feet below the top of the embankment. The impact scar from the wing is as near vertical as can be estimated (ignoring dihedral), and the scar across the railway lines is vertically above the wing tip point of contact ie the angle of bank was pretty much 90°, and backs up the CAB statement, “about 85°”.
Haven't seen the wing impact evidence on the embankment, and apologize for being late to the discussion. If the impact scar was caused by a wing, the angle would depend on the velocity of the wing tangential to the obstruction, no? An embankment has a grade, what was it? A wing has dihedral, and a heading, plus a velocity of its own. Those are a lot of factors to be considered to arrive at a conclusion "the wing had a ninety degree aspect at impact".
I may be way too behind to merit comment here, but my initial queries would include:
Did the pilots have aileron command? Was the Rudder operating as designed? Were the pilots trying to gain directional control by differential thrust? If there was a severe vibration before impact, was its origin determined? Collecting serial numbers of each propellor blade, was it possible to recreate the path of each?
Having experienced Whirl Mode on an early Electra as pax, abeam the wing, I can testify to the alarming behavior of wing/power plant. It would have been an extremely difficult recovery in normal flight, let alone one hobbled by inop ailerons. What about walk around, controls checks? Depending on the orientation of the prop strikes, would it be possible to determine if the power plants were even still attached prior to impact? Had one separated prior to impact would certainly explain inversion of the airframe.