scope:

Description of Driving Event:

Inspection of the Nose Landing Gear (NLG) tire revealed a 1/4" cut which appeared to have a small piece of wood embedded in it. The investigation of the tire included: (1) X-Rays that verified the position and size of the wood chip; (2) review of the standard holography inspection data that verified the technique failed to reveal the defect; and (3) sectioning of the tire to determine the origin of the chip. The wood chip came from the cart used to transport the tread gum rubber to the tire builder and was built into the tire. The wood chip became visible only after inflation. All existing orbiter tires were X-Rayed to screen for similar defects and tire inspection techniques were changed to include X-Rays. The wood chip caused a delamination sufficient to produce a tire failure under some worst case, but feasible, landing scenarios (maximum permissible cross wind at KSC). However, the other NLG tire would have supported the orbiter following this failure.