NASA ready for final STS-116 approval

Discovery, on launch pad 39B, enjoyed an uneventful TCDT (Terminal Countdown Demonstration Test), with only a CRT – part of the orbiter’s control system displays – failing during the two day test. That CRT has been replaced at the pad.

Other pre-launch activities are proceeding to plan, with the completion of orbiter APU (Auxiliary Power Unit) hydrazine loading, added to the loading of oxidizer into the OMS RCS (Orbital Manoeuvring System Reaction Control Systems).

Some troubleshooting exists – as with any pad flow – mainly relating to electrical elements on the orbiter, including the Advanced Health Management System (AHMS), which will debut on this flight.

‘Plan to troubleshoot MTU signal after SCAPE is complete,’ noted the expansive Shuttle Stand-up/Integration Report for November 20 (on L2). ‘Will install hydraulic trays and hoses to re-run SSME FRTs. SSME actuator calibration coefficients were not written to the new AHMS, which was their procedural error.

‘Caught error and will re-run FRTs on engine Wednesday. If complete FRTs, will power down this weekend. Have much powered-down work to perform.’

The AHMS is suffering from some teething problems, but will not have any constraints on STS-116, given it will be installed on one of Discovery’s SSMEs (Space Shuttle Main Engines) to test its own reactions to the pressures endured during ascent. It will not have any control over the engine on this flight, along for the ride as a passive system.

‘Working on command sequence discrepancy (for SSME actuator calibration coefficients not written to new AHMS) with USA Avionics. Concur that need to repeat engine 3 actuator calibration test performed at launch pad,’ added SSME managers at Pratt & Whitney.

‘Problem is calibration coefficients are written into temporary memory (S-RAM) and a command is required to transfer memory contents to EPROM (permanent memory). The command failed the checkout.’

Also relating to SSMEs is an investigation into a crack on one of the blades on an engine pump that flew with Atlantis on STS-115 earlier this year. The fault is deemed as minor.

‘Dye penetrant inspection on STS-115 pump 8222 showed indication on one first stage blade on platform (.020 X .030 X .020 inch deep). Broke platform open, and metallurgy reports said appeared to be anomalous grain. Size of crack is well below critical initial flaw size for area (.045 inch). Mr. Hale (Space Shuttle manager) asked for more information as investigation continues.’

Meanwhile, on Atlantis herself – set to fly on STS-117 next spring, her related processing flow continues, ready to support her sister as the LON (Launch On Need) rescue ship. Work is proceeding along the scheduled timeline.

‘Down to 102 tile cavities to bond. Plan to bond 11 this week. Chin panel fit checks in work. Plan powered-on testing today,’ added the report. ‘Plan SCAPE operations at 5:00 a.m. EST tomorrow to backfill manifolds for thruster R&R performed last week. Plan waterproofing Friday and Saturday.’

Stacking in the VAB (Vehicle Assembly Building) of the twin Solid Rocket Boosters (SRBs) that will help power Atlantis off the pad will begin on December 4, following the delivery of the segments that make up the boosters. Repair work on the VAB doors will also begin on December 4.

On the External Tank front, workers at the Michoud Assembly Facility (MAF) have one again proved their worth, with ET-124 (required for LON and STS-117) still on schedule to be shipped out of New Orleans on December 17. However, a couple of production issues might delay the shipping by a few days – which is still within the required timeline for LON support of STS-116.

This tank also saw the remaining pressure on its schedule removed when NASA’s Critical Design Review (CDR) on the modification of three IFR (Ice Frost Ramps) decided to leave the ramps ‘as is’ – given wind tunnel testing showed there was no notable improvements gained from ‘sliming down’ the ramps. Further evaluations will continue for future tanks.

‘Wrapping up preparations for reinstallation of composite nose cone. Should secure nose cone this (week). LOX ice/frost ramp extensions trimmed. Trimming acreage spray on PAL ramp footprint. Bipod installation in work; about 20 percent complete on final routing and bonding of bipod heater and temperature sensor harnesses.

‘Intertank venting and machining in progress (machining about 95 percent complete). Camera antenna about 99 percent complete, and should closeout next Monday. Harness routing on intertank about 85 percent complete associated with antenna. LO2 feedline fairing installed. Will spray 1979 drip lips tomorrow.

‘These have been problematic, so have gone back on proficiencies and are taking results to technical subcommittee today for review. Completed last four 2026 drip lips. Preparing to install upper ice/frost ramps. Shakedowns are in work all over tank. Are few days down from December 17th delivery date, but are rerunning assessment today to replan with same target date.’

With many tanks now in various stages of processing, ready to support the busy final schedule for the Shuttle program, MAF continue to keep up the pace on the tanks required from the other missions of 2007.

ET-117 is now in Cell A at MAF, heading into final assembly. This tank is only a few days behind schedule. ET-120 is also moving through the MAF factory.






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