internal joints of the nozzle metal parts have been redesigned to
incorporate redundant and verifiable O-rings at each joint. The
nozzle steel fixed housing part has been redesigned to permit the
incorporation of the 100 radial bolts that attach the fixed housing
to the case's aft dome. Improved bonding techniques are being used
for the nozzle nose inlet, cowl/boot and aft exit cone assemblies.
The distortion of the nose inlet assembly's metal-part-to-ablative-parts
bond line has been eliminated by increasing the thickness of the
aluminum nose inlet housing and improving the bonding process. The
tape-wrap angle of the carbon cloth fabric in the areas of the nose
inlet and throat assembly parts was changed to improve the ablative
insulation erosion tolerance. Some of these ply-angle changes were
in progress prior to STS 51-L. The cowl and outer boot ring has
additional structural support with increased thickness and contour
changes to increase their margins of safety. Additionally, the outer
boot ring ply configuration was altered.