FRCS issue on Atlantis relates to wiring – 24 hour fix

by Chris Bergin

United Space Alliance engineers have been troubleshooting an issue with Atlantis’ FRCS (Forward Reaction Control System) oxidizer gaseous helium isolation B valve, which is “stuck” in the open position.

Updating status, engineers at the pad found a loose grounding wire, which – following repairs or replacement – should clear the valve as operational by the end of the weekend, keeping STS-122 on track for a December 6 launch date.

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The issue was noted during pre-launch processing on Atlantis, as she moves closer to her December launch on STS-122.

The valve isn’t closing when commanded, so engineers this morning are conducting a ‘wiggle test’ on the wires, as part of an evaluation into whether the problem is electrical, or if the valve itself is faulty.

‘Picked up an IPR (Interim Problem Report) on FRCS oxidizer gaseous helium isolation B valve, which isn’t closing when commanded to do so.

‘Plan is to go into fuel loading, access this area tomorrow, do wiggle test on wires, and verify whether valve is stuck open or there is an electrical problem,’ noted the latest Stand-up/Integration report.

‘Engineering going through troubleshooting plan. Three teams formed to work on this plan: Team 1 will look at troubleshooting plan and ensure coordinated with all engineering communities. Team 2 will look at path to fly as is. Team 3 will determine what it will take to repair this valve.

‘Will have data and a recommendation by Monday.’

‘RH (Right Hand) door will be removed and a BOB (Break Out Box) will be installed at the 22P66 connector. Electrical checks will be performed to determine if the problem resides in the valve assembly or vehicle wiring,’ noted processing information on Friday. 

‘If the determination is that it is the vehicle wiring, then an alternate power path will be provided to the valve. This will verify that the valve functions nominally and that an alternate power path may be a feasible alternative. Further discussion will be required to determine technical direction ‘

UPDATE: During continuity checks at the pad, engineers found that the problem does indeed relate to wiring, which will be repaired this weekend. Following this process, the valve should work properly, when the vehicle is next powered up.

Meanwhile, Flight Director Holly Ridings noted that the launch date for STS-122 is now back on track for December 6.

‘With the extra work our crew has done on orbit and a tremendous amount of effort by the team on the ground, I am proud to tell you we have anominal plan for a 1E launch on 12/6,’ noted Ridings to her team.

‘This was accomplished without any major reduction in content; simply smart and proactive management of the activities by the entire E16 team and the incredible efficiency of our crew.’

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