STS-122: Reviewing Atlantis’ IFAs – Parachute failure tops list

by Chris Bergin

Atlantis, now undergoing post-flight deservicing inside OPF-1 (Orbiter Processing Facility), has already received her expansive mission report.

The IFA (In Flight Anomaly) Reviews have already been presented to the all-powerful PRCB (Program Requirements Control Board) – with the main focus of attention on the failure of one of the Solid Rocket Booster (SRB) parachutes, which damaged the left hand booster.

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**STS-122 Special: 29 Flight Readiness Review (FRR) Presentations, Baselines and Mission Overviews. **Click here for FRR overview articles: Article 1Article 2** Payload Presentations and vast amounts of live, uploaded images and presentations, movies (several) – already 3900 megabytes strong**

**STS-122 MMT Level now into post flight IFA Reviews.
**STS-123 L2 Special Build-up in full swing (MOD FRR Presentations and Processing). STS-124 Sub Section Build-Up.
**STS-125 Sub Section Special already over 1000mb in size.

**LIVE updates on Atlantis STS-125 Processing Flow and STS-122 Post Flight**

**LIVE updates on Discovery STS-124 Processing**

 **LIVE news updates on Endeavour STS-123 Processing**

STS-122 ECO related news content (all exclusives): *Scrub 1* – *MMT Debate* – *Scrub 2* – *Hale Memo* – *Forward Plan* – *Culprit Found* – *Tanking Test* – *Repair Options* – *MAF Plan**PRCB Debate* – *Plan Approved* – *Repair Schedule* – *Launch Date* – *New Issue* – *Hale Rallying Call* – *PRCB Launch Dates* – *New Connector Installed* – *Positive Test Results* – *Manifest Impacts* – *Optimism with forward plan* – *Flight Rationale* – *Repairs Finalizing* – *Root Cause Confirmed*

STS-122: Hose related news content (all exclusives): *Issue found/fleet to be checked (December)* – *Atlantis found to have problem* – *Managers discuss forward plan* – *Use of pole to aid retract* – *Successful Retraction*

STS-122 Post Flight Review:

STS-122 is being classed as the ‘cleanest’ flight – by way of TPS (Thermal Protection System) health and lack of issues with Atlantis herself – for many a year. However, the IFA review is a crucial process that is required on several levels.

Firstly, the review aids processing flow requirements to bring Atlantis back to flight readiness, in preparation for her next mission – STS-125 to service the Hubble Space Telescope. Secondly, any orbiter wide issues found with STS-122 can become a constraint to the next mission – STS-123 with Endeavour.

In a fitting conclusion to a delayed mission – due mainly in part to the ECO (Engine Cut Off) sensor system problems – Atlantis enjoyed a relatively issue free flight, according to the IFA review.

‘Mr. Hale congratulated the entire team on the success of the STS-122 mission, which represents a huge investment and sacrifice of time and effort of so many people around the Program,’ noted the latest Stand-up/Integration report on L2 – Hale’s last. ‘It was wildly successful in terms of what was accomplished.

‘Folks that prepared the vehicle for flight did an outstanding job. The list of post-flight funnies is remarkably small; this is a credit to the engineering team and all the folks who did hands-on work at the OPF. The propulsion systems operated flawlessly.

‘We were outstandingly successful in solving our problems with the ET circuitry (ECO related issues and LH2 Feed-through connector R&R).’

The Ed Mango led ECO sensor system resolution team can now class the issue as closed, with all future tanks now utilizing the soldering of the pins mitigation method on the LH2 Feed-through connector as the baseline. No further issues are expected for the remaining shuttle countdowns.

IFA Review: SRB:

As observed on cameras placed on the SRBs – used to capture ascent damage on the ride uphill, and the booster’s return to splashdown in the Atlantic – one of the three main parachutes on the left hand booster failed to inflate.

This was caused by a 25 foot long tear in the canopy, meaning the booster hit the ocean at a much higher speed than expected. Root cause evaluations still ongoing.

‘Exhibited large hole upon deployment and never able to inflate. Water impact velocity higher than normal. Significant damage to aft skirt assembly,’ noted the IFA Review presentation on the SRBs.

‘Nine previous failures of one damaged main parachutes. Anomaly Resolution Team formed. Post-flight inspection of ordnance ring, parachute bags, parachute and frustum interior found no evidence indicative of frustum contact.

‘Initial parachute inspection found no obvious areas indicating cause of tear. Detailed damage mapping of parachute on-going. Fault tree in work to establish potential failure modes. Closure efforts include review of pedigree, event times, repair history, and parachute material characterization.’

The damage to the aft skirt assembly is likely to see that element of the booster scrapped, especially after the damage resulted in the hardware leaking hydrazine, after it was recovered from the ocean.

However, this was the only ‘major’ issue observed with the boosters during their flight, with ‘No Operations and Maintenance Requirements and Specifications Document (OMRSD) or Launch Commit Criteria (LCC) violations, added to ascent data assessment indicating nominal SRB system performance.’

Classed as ‘Squawks’ – several other elements of the booster were focused on, mainly relating to slight TPS (Thermal Protection System) impacts – all of which are nominal. However, another area of interest also related to the booster parachute system, noted as a ‘suspect SWAR (Sea Water Activated Release) failure to release.’

The SWAR provides a method of disconnecting main parachute from SRB after splashdown, with the immersion in seawater closing an electrical circuit to release a shear pin from the riser about two seconds after immersion. This failed on the right hand booster.

The SWAR was fully implemented in 1998 on STS-95, in order to increase diver safety by eliminating need to cut parachute lines. The problem with STS-122’s booster is believed to be associated with a known failure mechanism with pyrotechnic train, when the primer fails to breach three millimetres stainless steel booster closure cup with enough energy to ignite charge in booster.

This issue will undergoing follow-up evaluations, though it is not a constraint to STS-123, given the lack of flight safety risks.

IFA Review: Orbiter Systems:

Atlantis performed extremely well on orbit, with only a handful of issues reported. Three IFAs have been reviewed, with none a constraint to STS-123’s upcoming launch on March 11.

‘APU (Auxiliary Power Unit) 3 Drain Line Off-Nominal Heater Cycles: APU 3 Fuel Seal Cavity Drain Line heaters exhibited heater off set-point shifts. Shifts noted on both drain line temperature sensors with corresponding shifts in drain line pressures. A total of four anomalous heater cycles were seen,’ listed one of the IFA review presentations.

‘To avoid a heater failure during crew sleep, ‘A’ heaters were deactivated and the ‘B’ heaters activated. Most probable cause is the controlling thermostat. Post-Flight Plan:• OV-104: Troubleshoot, and R&R thermostat. OV-105/103: None.’

‘Fuel Cell 3 O2 Flowmeter Erratic: Fuel Cell 3 O2 flowmeter reading went off scale low for about two minutes, then displayed unreliable and erratic data for remainder of mission. A review of the electrical bus did not show any anomalous indication at the time of the failure. Considered failed, and on-board class 3 FDA limit was inhibited.

‘Fuel cell flowmeters failures have been seen before (obsolescence issue). No impact to mission or crew ops. Post-Flight Plan: OV-104: T/S to verify the failure is in the flowmeter. OV-105/103: None.’

‘Aft RCS (Reaction Control System) Manifold 5 Heaters Failed: On Flight Day 12, an electrical current spike across all three fuel cells was observed. Within five minutes injector temperatures on L5L, L5D, R5D, R5R began decreasing indicating their respective jet heaters had lost power.’

This issue occurred near the end of Atlantis’ mission, with the venier thrusters in question not required for the deorbit or re-entry phases of the mission.

‘The spike observed was consistent with the amperage and duration required to open the 5 amp internal fusible link in the Hybrid Driver of Load Control Assy 3. L5L annunciated fail leak and was auto-deselected by RCS RM. VRCS attitude control was lost; Alt PRCS was used for remainder of flight.

‘It is likely there was a short circuit in one of the heaters, the wiring to the heaters, or within the Hybrid Driver itself that cause the observed signatures. Post-Flight Plan: OV-104: T/S plan in development. OV-105/103: None.’

IFA Review: Debris:

Tagged as the cleanest flight since Return To Flight, ET-125 performed extremely well, added to various other ‘debris’ hazards associated with Atlantis’ ascent.

Systems Engineering & Integration (SE&I) IFA review presentation noted only eight debris related IFAs, with the focus of attention pointed at a stinger tile that was observed falling after SSME (Space Shuttle Main Engine) ignition.

Several camera views caught the stinger falling off the aft of Atlantis, recorded at T-3.463 seconds.

While no damage resulted from the loss of the tile, it will be evaluated for database purposes, along with post flight processing inside the OPF.

Other debris related IFAs – classed as impacting the vehicle – all caused nothing more than cosmetic damage. They are listed as:

‘Multiple Debris Pieces seen at MET (Mission Elapsed Time) 132 sec. LH2 acreage loss adjacent to Xt 1129 Lo2 feedline base closeout (multiple pieces released). Exceeds mass allowable. Ascent Debris impact to SSV.

‘Debris seen at MET 440 sec Impacting Orbiter. LH2 acreage loss aft of +Y bipod. Exceeds mass allowable. Ascent Debris impact to SSV. Debris seen at MET 93 seconds. LO2 umbilical cable tray foam loss (aft of Xt-2058). Exceeds mass allowable. Ascent Debris impact to SSV.

‘I/T (Intertank) to LH2 Flange closeout foam loss. Foam loss at I/T to LH2 flange closeout at 5-6th stringer +Z of –Y thrust panel (MET 85 sec) and 3rd stinger +Z of +Y thrust panel (time of loss unknown). Outside of risk assessment for time of occurrence and frequency of release. Ascent Debris impact to SSV.’

IFA Review: Flight Software:

A few issues were noted with Atlantis flight software, mainly relating to the Rendezvous Proximity Operators Program (RPOP) and the KFX Payload General Support Computer (PGSC) – which required rebooting.

‘Suspect PGSC 3Com Network Card: On Flight Day 11, Orbiter Communications Adapter (OCA) officer reported an intermittent problem with the KFX Payload General Support Computer (PGSC) dropping off the network,’ added the related IFA review presentation.

‘Problem persisted until the Ethernet PCMCIA (3Com) card was swapped and system rebooted. No mission impact due to availability of four spare 3Com cards.’

A post flight plan has been activated, which will see the hardware tested. Notably, the presentation adds that, starting with STS-123, new wireless access points will replace 3Com network hardware.

‘Backup RPOP Not Receiving TCS Data During Undock: During rendezvous and docking operations, the HHL was operational but its data was not downloaded to the Rendezvous Proximity Operators Program (RPOP) PGSC.

‘Post-docking analysis of downlinked RPOP and Trajectory Control Sensor (TCS) data indicated that the backup RPOP/TCS laptop did not receive TCS data during rendezvous,’ listed the presentation on the other issues.

‘The problem was reproduced during rendezvous tools checkout on FD11, and the RS-422 Quatech card was replaced to restore proper operation. No mission impact due to availability of three spare cards and redundant TCS PGSC.’

‘Handheld Lidar (HHL) Data Not Feeding Into RPOP: During rendezvous and docking operations, the HHL was operational but its data was not downloaded to the Rendezvous Proximity Operators Program (RPOP) Payload General Support Computer (PGSC).

‘During rendezvous tools checkout on FD11, the RS-232 HHL interface cable was replaced in the course of completing the checkout procedure and verifying proper operation. No mission impact due to availability of spare cable and manual workarounds for HHL use.’

IFA Review: Range and Communications:

Several presentations also referenced communication issues, some of which relate to the KU Band Antenna and high speed tracking data.

However, one pre-launch communication issue between the range and controllers at the Johnson Space Center (JSC) resulting in a couple of seconds of delay/latency on the data relay. This gained a large amount of attention on the IFA review presentations.

‘During the STS-122 count Cape DRSD (Distributed Range Safety Display) to JSC was experiencing timing delay in excess of two seconds,’ noted unclassified information from the 45th Space Wing’s IFA review report.

‘The delay was determined to be within the MOC (not due to circuit). DRSD was rebooted and the excessive delay went away, but it returned less than one hour later.’

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The cause of the issue has already been determined to be the ‘estimation processor’ and technicians have created a workaround to be in place for STS-123 and subsequent launches.

‘During the system start-up the Estimation Processor is overloaded with the task of processing all initialization sequences. Once all sequences have been completed and displays have been initialized, a simple re-initialization of the Estimation Processor resets the timing.

‘This workaround will have no effect during launch and only takes one minute to complete. Work around has been tested several times and has proven to reset the timing sequence within expectable limits.’

Hale: Great start to the year:

Bar those already known, such as the slightly protruding blanket on the starboard OMS Pod – which did not prove to be an issue during re-entry – the other IFA review presentations epitomised the relatively issue free flight Atlantis enjoyed.

Activation problems with the Columbus module were soon resolved by controllers on the ground, along with minor issues with the video downlink that was not picture perfect during some elements of the mission.

Some confusion remains on the status of Atlantis’ starboard aft radiator retract flex hose – which required troubleshooting at the pad pre-launch, due to an omega kink during Payload Bay Door closure.

Despite the crew reporting that all four hoses retracted without issue on orbit – ahead of re-entry – some unconfirmed reports claim the starboard aft radiator retract flex hose once again kinked.

However, and importantly, the loop did not leak its freon coolant, which was the only concern relating to such a kink in the hose and would have seen the implementation of the loop being isolated during re-entry and landing.

Overall, the health of Atlantis’ TPS was the cleanest since RTF – despite more Regions Of Interest (ROIs) being noted on this mission, compared to previous RTF missions. Those ROIs were all cleared as not being any issue and were mainly cosmetic.

‘(Mr Hale) is impressed by everything, and the results are that we have the Europeans firmly established on the International Space Station,’ added the latest Stand-up.

‘The international aspect of this project has come to the forefront, and the IFAs will support us and future projects. Packing on the middeck going up and down was also unbelievable.

‘It was a great flight and is a start to a busy year.’

L2 members: All documentation – from which the above article has quoted snippets – is available in full in the related L2 sections, updated live.

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