Engineers evaluating radiator hose issue on the fleet

by Chris Bergin

While the focus continues on the replacement of a suspect connector inside Atlantis’ External Tank, engineers are evaluating a problem with a radiator hose on Discovery – which is causing a launch constraint concern with STS-122.

While the hose will likely be replaced on Discovery, engineers are assessing if they need to gain access to Atlantis’ cargo bay, in order to carry out boroscope inspections – due to the possibility of finding a cracked hose – which may cause a Freon leak on orbit.

**The most comprehensive collection of Shuttle, Ares, Orion and ISS related presentations and mission documentation, plus expansive daily processing documentation and updates are available to download on L2 **

L2: STS-122 to STS-127 documentation already available.

STS-122 L2 Special NOW LIVE. **Click here for sample of L2 menu and content**

**STS-122 Special: 12 MOD Flight Readiness Review (FRR) Presentations, Baselines and Mission Overviews. 17 Shuttle FRR Presentations. Payload Presentations and vast amounts of live, uploaded images and presentations. Installation Movies (several) – already 1700 megabytes strong**

**COMPLETE Section on ECO/Feedthrough Connector issues and troubleshooting, graphical and data based – expansive.**

**LIVE updates on Atlantis STS-122 Troubleshooting Latest**

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**Click here for FRR overview articles: Article 1Article 2**  – Click *HERE* for all our articles on the STS-122 ECO/Feedthrough Connector issue.

ET-125 Troubleshooting Latest:

All three orbiters are currently powered down for Christmas, with work continuing on the preparations for the removal of the LH2 Feed-through connector inside of ET-125. A carefully planned TPS (Thermal Protection System) foam removal procedure was drawn up by United Space Alliance and Lockheed engineers, in order to protect the rest of the tank.

‘Will return on December 27 and complete remaining foam removals and removal of connectors,’ noted processing information on L2. ‘Will then repressurize the tank and complete work around December 28/29.

‘Continuing to work through various R&R scenarios as discussed for STS-122/ET-125. Now working through and prioritizing what makes sense as begin gathering additional information on processing and hardware performance. Key activities include development of dissection plans for TPS.

‘Are removing cable trays and preserving electrical connector on ET-125 as much as we can. Building up test hardware and doing development work on facilities to perform cryo test of hardware.’

Aft Radiator Hose Issue:

Due to the focus on the suspect connector, the usual troubleshooting – which is a natural part of any pad flow – has not required the full attention of shuttle management. However, a new issue has now been elevated for evaluation by the Orbiter Project Office’s of NASA and the United Space Alliance.

‘Issue on OV-103 (Discovery). When closed doors recently, noticed right aft radiator retract hose didn’t retract back into box. Excess hose that connects Freon loop to radiator kinked in door. Hasn’t happened before,’ noted the Stand-up report on L2.

‘Have done boroscope of area, and video is available, but doesn’t show any obvious root causes. Will cycle door to determine how hose reacts. Safety folks involved and are concerned of possible crack in hose that may cause Freon leak.

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‘Plan is to determine as much information as possible and have door in safe configuration before holidays. May need to R&R hose. Program assuming remote possibility that we may be able to fly hose as-is based on rationale and X-rays verifying no internal damage to hose.’

Given Discovery isn’t due to fly again until STS-124, time is on the side of engineers in the Orbiter Processing Facility. However, the first-of-its-kind issue has raised questions on the status of the hose on the other two vehicles – especially Atlantis.

‘Radiator hose concern is constraint for STS-122. When looked for root cause, found no obvious blockage. KSC may need to determine a way to go into bay and inspect these hoses. For now, performing door cycles and visual observations, which probably won’t get us to a root cause.

‘Need to understand configuration for OV-104 and there would then be a risk discussion relative to flight rationale.’

Additional Atlantis Troubleshooting:

Troubleshooting is also taking place on the ATVC (Ascent Thrust Vector Control) box – a system used to move the orbiter’s main engine nozzles during launch – in Avionics Bay 5. Access to Atlantis’ aft is available due to the recent the ECO (Engine Cut Off) sensor troubleshooting.

This box had previously suffered issues on Discovery ahead of STS-121, due to a phenomenon known as ‘tin whiskers’ – which caused a major evaluation by shuttle managers, following a dissenting opinion by the Aerospace Corp. However, Atlantis’ issue is not serious, with a spare available, should engineers need to replace it.

‘ATVC problem on OV-104 (Atlantis). Actuator signature is erratic until after the box has been on for awhile and is warm, which is when everything goes back to normal. Could be due to thermal issues inside box or due to wiring between box and actuator.

‘Troubleshooting plan is to swap driver output and swap twp actuators at the box and determine if problem follows swap. Part of plan is to look at MDM where signal comes out of box. Should be able to isolate problem. If problem is in box, have spare for R&R. More to come on this; have a good plan to isolate root cause.’

STS-123 Processing Latest:

With the launch date for STS-122 still anywhere between January 10 and March, Atlantis’ younger sister, Endeavour, has seen processing milestones for her mission, STS-123, remain under evaluation.

Following a slight hiccup in her processing flow, with a leaking Main Landing Gear (MLG) strut, which required engineers to changeout the seals inside the gear, Endeavour is to all intents and purposes ready for rollover to the Vehicle Assembly Building (VAB). That, of course, is on hold, pending the reviewed launch date for Atlantis/STS-122.

‘Completed aft structure leak checks. Also working troubleshooting on Shuttle Orbiter Repackaged Galley (SORG); there’s a potential tank R&R that would occur after holidays. Retracting gear, doing step and gap, and performing landing gear functionals after holidays,’ noted processing information.

‘Tank and booster activities – Continuing with closeouts on system tunnels. Moved ET/SRB mate date to no earlier than January 2.

‘Not much work planned over the holidays. When they get back, they will be able to go into the OTS (Orbiter Transporter System) operations, weight and C.G. (Center of Gravity), etc. Will try to get into a position to roll out on January 8, which is a day earlier than originally planned.

‘Want to try to get to a point where they are not in competition with launch (STS-122) on January 10, 2008 (No Earlier Than). If they can get over on January 8 they will be able to secure vehicles by January 10 and not have any interruption of operations. Plan on having about 60 people working through the holidays on the ET, and will take the two days off that have been outlined.’

While STS-122’s launch date remains fluid, managers are continuing to plan ahead with the upcoming flights, to ensure they are in a strong posture in the event Atlantis manages to launch in January.

‘Started looking at FRR (Flight Readiness Review) for STS-123. It looks like the Level 1 FRR will be on February 8, 2008, per Mr. Gerstenmaier’s request,’ added the Stand-up. ‘Will look at doing the Program FRR the week before, depending on where we get on STS-122.’

STS-124 Processing Latest:

Back with Discovery, her post flight (STS-120) processing is continuing, ahead of her next flight (STS-124). In addition to the aforementioned issue with the radiator hose, Discovery has seen four of her RCC panels removed, following the issues with weakened SiC to carbon substrate adherence, or ‘debonding’ of the top layer of the panels. The issue is currently going through the process of a Tiger Team level evaluation.

STS-124’s crew also visited the Michoud Assembly Facility (MAF) in New Orleans to look at the External Tank they will be flying uphill with, ET-128 – which is a modified tank that will debut the final changes to the Ice Frost Ramps (less foam – replaced by titanium), in what will be a test of the new tank ahead of the flagship mission to Hubble (STS-125).

‘STS-124 crew at MAF to look at ET-128. Have installed two of the titanium yokes. All ice frost ramps, LOX and LH2 tank are in work, and are preparing for a longeron spray. LNC feedlines are in final checkout and ready to be installed,’ noted processing information.

‘Critical path remains through ice/frost ramp installation activities and longeron sprays. Have all lower ice/frost ramp pours in place; puts them in position to begin faring installations and pressurization line installation activities.’

Preparing for 2008:

Despite failing to make it four flights in a year for the first time since 2002, the amazing recovery from major processing issues, such as the hail damage to STS-117’s External Tank, the leaking MLG strut on Discovery and the ambitious processing flow plan for dual High Bay use, has seen 2007 become an overall success for the shuttle program.

This was noted by deputy shuttle program manager Kim Doering at the latest Stand-up meeting, with her added emphasis on 2008 – arguably the most important year of shuttle operations for a decade, with around five missions, including the final trip to service Hubble.

‘It has been an amazing year. This is the time to recuperate, because next year will be busy as well,’ Ms Doering noted. ‘Many folks had to sacrifice time away from friends and family. Hope when you reflect back on accomplishments, that you feel it was time well used.

‘Have done good work here and are proud of the team.’

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