Space Shuttle Endeavour sits poised for launch at NASA Kennedy Space Center's Launch Pad 39A after technicians replaced the Load Control Assembly-2 (LCA-2) in its aft section. Located in Endeavour's aft avionics bay 5, the LCA-2, which distributes power to nine shuttle systems, is believed to have caused fuel line heaters for Endeavour's auxiliary power unit-1 (APU-1) to fail 29 April during the first launch attempt for the STS-134 mission and has been replaced. Systems will be retested before the launch is rescheduled.