Fuel Cell forces Atlantis scrub

by Chris Bergin

NASA have been forced to scrub Wednesday’s launch of Shuttle Atlantis, following a “lost phase A on the FC coolant pump motor” on Fuel Cell 1.

Engineers are working on a troubleshooting plan, although Atlantis will not be able to launch in the early September window if a replacement of the Fuel Cell is called. Live updates are being posted, along with supporting presentations that are being evaluated by NASA. See live update pages below.

**L2 STS-115 Coverage: L-2 and L-1 MMT Notes. ALL related handbooks, from Final Flight Plan to EVA Presentations (550mb of 115 presentations downloadable)**

**STS-115: Launch Attempt: SCRUB Update Page** – One stop LIVE updates.

KEY EVENTS: (Colour code: Red ‘No Go’ – Green: ‘Go’)
External Tank Weather Orbiter Range.

Key Points/Newsflashes: Expect rollback of the vehicle. Update: 21 PDFs going to MMT available to download on L2.

Follow the above live update thread for live updates from internal NASA reports.

Current News Roundup

‘Launch scrubbed for 24 hours due to fuel cell problem,’ noted the official document being sent around NASA officials. ‘Plan is to meet w/ vendor in the morning.’

While the next attempt will take place on Thursday, a replacement of the fuel cell would rule out the current 6th to 8th launch window. A Mission Management Team (MMT) meeting will take place at midday to evaluate.

All three fuel cells need to be working to allow for a launch to proceed.

‘Fuel Cell 1 Summary: EGIL and KSC saw indications that FC 1 had lost phase A on the FC coolant pump motor,’ continued the internal report. 

‘There was a current spike on AC1 ÖA of approximately 0.9 amps. This was followed by an increased continuous load of 0.11 and 0.07 amps on phases B and C, respectively.

‘Phase A then dropped to approximately 0.5 amps below the previous run current. FC 1 is currently connected to MNA in order to bring up the operating temperature. This will place the FC in a better condition if KSC decides to stop the pump package to evaluate the coolant pump.

‘KSC opened an (note of problem). Meeting at 0200 (7am UK time): No go for launch today. No confidence in phase B and C.’

The coolant pump is a motor and requires 3 phases of AC to work properly (although 2 phases may or may not work in some cases). The higher currents on that phase (A of AC1) may indicate that the pump is the problem. 

It is likley engineers will take the pump off line and see if the indications on AC1 change, this will help narrow down the origin of the problem.

Other issues noted on the report included less minor issues – all of which will not affect another attempt tomorrow, if possible. 

‘Ascension Island down – ETRO 1600 GMT, 7 September – They have a computer difficulty which requires some hardware. There was some word about trying to get up for the next couple of passes, but the official ETRO remains the same.

‘Post Insertion Checklist – Shaded pictorials on pages 014, 015, A11 do not have panels for OV-104. Non-shaded, boxed switch configurations are correct. Crew has been informed.’

NASA has a launch window at the end of September (Sept. 24), if required. Documents on L2 show the opportunity exists, should the lighting restriction on ET photography be dropped. The next ‘lighted’ window opens at the end of October. 

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