Saffron:
there is a big difference between a skin and a plank,any electra engineer knows that the wing is not of the usual airliner constuction,these planks have had a corrosion problem. Because the planks are much thicker than your average wing skin they have a much greater stuctural load,the corresponding spars & stringers are lighter,an engineering trade off,whilst it is not economical or practical to reskin an airliner wing,many electras have had their wings replanked
The Electra wing planks as you call then are the wing skins. Large aircraft wing skins range in thickness from 1/4" to 3/4" and are machined from large planks of aluminum. If I remember correctly the Electra planks are 1/4" to 3/8" thick from inboard to outboard. As for the corrosion problems, name me one Lockheed aircraft that hasn't had wing corrosion problems?
Again I ask you to name me one large aircraft that doesn't use machined planks as wing skins?
By the way one of my job at Lockheed, for a short period of time, was at the Electra desk in the product support center.