Technicians and engineers at NASA's Kennedy Space Center in Florida have identified the likely source of what caused heaters on a fuel line for space shuttle Endeavour's auxiliary power unit-1 (APU-1) to fail on Friday, scrubbing the first launch attempt for the STS-134 mission.
The failure appears to be a power problem within the aft load control assembly-2 (ALCA-2), a box of switches controlling power feeds.
The plan is to remove and replace the box, but that work and related testing will take several days to complete. Once the new box is installed, the team must verify it's working properly -- at least a two-day process -- and perform forensics on the failed box.
Managers are expected to meet over the next day or two to determine the next launch attempt, but it is expected to be no earlier than May 8.
Workers at Kennedy's Launch Pad 39A have drained space shuttle Endeavour's external fuel tank of all cryogenics. The Rotating Service Structure was moved back around the spacecraft in order to protect the shuttle from the elements and to gain access to Endeavour's aft section.
After returning to NASA's Johnson Space Center in Houston, the six STS-134 astronauts will be involved in some additional training before they return for the next launch attempt.