Extra platforms required for sensor fault troubleshoot

by Chris Bergin

United Space Alliance workers will be installing extra work platforms around the aft engine compartment on Discovery, in order to search for a double sensor fault noted from last week’s Tanking Test.

Shuttle manager Wayne Hale described the April 14 test as an ‘outstanding day’, but not long after his press conference, workers were disheartened to hear that one of the four faults discovered on the Tanking Test was potentially troublesome.

A fault with an Engine Cut Off (ECO) sensor was detected, with a second ECO failing during the drain of the liquid Hydrogen from the External Tank (ET). The Shuttle has four ECOs – with all four needing to be operational or else a launch attempt would be scrubbed.
Various information was received at the time on what is to blame for the double anomaly, with one source noting how he ended his shift late on Thursday with the news from a colleague that he’ll be needing his “Bunny suit (clean suit) and a hammer” – as it was believed both faults were with the ET and couldn’t be solved on the pad.
Such a situation would almost certainly see the Stack rolled-back into the Vehicle Assembly Building (VAB) given access to correct the fault would be through the aft dome closeout/access panel, which had already been foamed and closed out on the ET.
However, latest information is pointing to the fault being on the Orbiter itself, with access through the aft fuselage engine compartment to find and correct the problem. The doors leading to that area of the Orbiter are routinely removed as part of the flow ahead of launch, yet extra platforms are being installed to gain access to where the fault is believed to have originated.
While it’s not cut and dry that this is the area that needs work, confidence is at least high that the troubleshooting will be targeted at the aft fuselage engine compartment section on the pad.
High winds at the Kennedy Space Center have so far hampered efforts to install the platforms in question.

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