Leak tests fail on Discovery delaying rollover – Atlantis’ ET arrives

by Chris Bergin

Discovery’s Right Main Landing Gear strut underwent further leak testing on Friday evening, following inspections that noted it was dripping hydraulic fluid on Friday. Engineers were unable to fix the problem to allow an on-time rollover for the orbiter ahead of STS-120. Rollover will be delayed a day or two, pending repairs.

Earlier, External Tank ET-125 arrived inside the Vehicle Assembly Building (VAB) following its barge trip from the Michoud Assembly Facility (MAF) in New Orleans. ET-125 will fly with Atlantis on STS-122.

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STS-120/Discovery status – UPDATED

The leak was observed by engineers inside OPF-3 (Orbiter Processing Facility) – which immediately underwent troubleshooting. Early indications on processing reports noted that it would not be a constraint to rollover.

‘Orbiter jackdown/weight/CG (Center of Gravity) completed yesterday (Thursday); OTS (Orbiter Transporter System) Operations scheduled for today,’ noted Friday’s processing report.

‘Picked up (problem), RMLG (Right Main Landing Gear) strut has higher than acceptable leak rate (allowed 1 drip/hour, currently seeing 1 drip every 20 seconds).

‘Gear was cycled five times last night with the following results: 1st cycle no drips. 2nd cycle 1 drip. 3rd cycle 5 drips. 4th cycle no drips. 5th cycle 1 drip. Strut is now extended with diaper installed. This issue may delay transporter operations, but should be no threat to rollover.’

However, further testing showed the leak was unacceptable, requiring repairs. This will carried out on Monday or Tuesday, leading to a slight delay to the rollover date, possibly by a couple of days.

‘All work for OV 103 (Discovery) has been cancelled due to main landing gear seal work,’ noted information on Saturday. ‘Repair estimated Tuesday or Wednesday.’

The launch date should not be affected unless they require the seals to be changed out – as there is remaining contingency in the current STS-120 flow, which is ultimately targeting a launch to the International Space Station (ISS) in a launch window that opens on October 23.

‘Payload bay doors closed in OPF. Did final power down at end of first shift. Strong backs removed from payload bay doors. Crew module hatch closed,’ summarized the latest Shuttle Stand-up Integration report.

STS-122/Atlantis status

Meanwhile, STS-122’s flow continues to remain within schedule, just, with the arrival of ET-125 marking a major milestone for the December mission. The tank – which had one of its LO2 Feedline brackets repaired during the final days of processing at MAF – will be integrated into its checkout cell over the weekend.

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Atlantis herself is enjoying a smooth processing flow, with her left hand Orbital Maneuvering System (OMS) pod set for installation late Friday.

‘MPS (Main Propulsion System) helium tank leak checks are complete and good. Had to change out a seal on helium tank #8,’ added the Stand-up. ‘Bolt seal bonds are in cure for LH OMS pod, and plan to lift and install pod on second shift Friday.’

The main constraint has been the lack of High Bay (HB) capacity for stacking the STS-122 boosters.

However, the recently drawn up mitigation plan appears to have worked out, with repairs to the High Bay 3 door proceeding ahead of schedule, which would see the boosters being stacked on the Mobile Launch Platform, a week before the STS-120 stack rolls out of the VAB from High Bay 1.

‘ET-125 goes to HB 4. Will have a Readiness Review with Ground Ops before move MLP in and before ready to process in HB 3, which will be around September 22 or 24. Will try to use HB 3, and have things in place there,’ noted processing information.

‘Everything on track in VAB HB 3 to process STS-122. Turnover for flight hardware processing is expected September 22.’

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