24-10-2012, 02:12 PM
Providing a Turn for the Better
ABSTRACT
Engineers are tasked with designing new systems every day to meet changing or unexpected technical requirements. After
the tragic explosion of the Space Shuttle Challenger on January 28, 1986, NASA engineers embarked on a complete overhaul
of many of their long-standing quality systems and procedures. When the official cause of the accident was determined to be
an O-ring failure in the right Solid Rocket Booster, NASA’s Shuttle Program initiated a thorough redesign of the rocket
boosters’ clevis ends, which are the O-ring’s mating surfaces. One of the unique systems that NASA engineers developed as
a result of this effort included a heating assembly that is coupled to the outside of the rocket boosters. When the assembly is
affixed to the external surface of the boosters, the very nature of its design allows for the warming of the O-rings prior to
launch. After the engineers completed the assembly’s design, however, they found that it was nearly impossible to tighten the
spanner nuts required for attaching the system, given the minimum amount of clearance they had in the limited and confined
space. Under these circumstances, the standard wrenches typically used for tightening these types of nuts did not work, and
there were no other existing devices to solve the problem. NASA engineers embraced the challenge, developing a torque
wrench tool adapter that allowed for a full rotation of spanner nuts in confined spaces. The tool, which is similar to an
open-ended crowfoot wrench and a fixed-face spanner wrench, contains two dowel pins that center and lock the wrench onto
the nut.