Double spider stiffening assembly for fan blades

Claim 1

A fan blade spider arm mounting assembly of the type including hub and spider arm sheet metal workpieces for mounting fan blades, wherein the mounting assembly is defined by two sheet metal workpieces, each having integral angularly spaced fan blade mounting arms joined to a central hub portion at the root of each arm, the workpieces angularly aligned and in superimposed relation, to thereby define double-thickness hub and spider arm portions, an outwardly extending rib at the root portion of each spider arm, the ribs of one workpiece oppositely facing the ribs of the other workpiece to thereby define a closed cavity at each spider arm root portion, the cavities being of lesser width than the width of the spider arms, the hubs and arms of the two workpieces being in abutting, facing relation to each other, the two workpieces being fastened to each other at their arms radially outwardly of said root portions, whereby each spider arm is stiffened by both compressive and tensile loading of its corresponding cavity walls when a transverse force is applied to that arm.