NASA/Lockheed Martin managers approve ET-124 repair plan

by Chris Bergin

Repairs proper will begin on Friday for ET-124, following the NASA/United Space Alliance TIM (Technical Interchange Meeting) on Wednesday, and Lockheed Martin’s presentation to the powerful PRCB (Program Control Requirements Board) meeting on Thursday.

While there’s a long way to go in the process, documentation confirms they will proceed with repairs on ET-124, rather than calling for a change of tank to ET-117, which would have pushed STS-117 to June. A May launch date appears most likely at this stage.

**The most comprehensive collection of STS-117 onwards related presentions and mission documentation – not available anywhere else on the public net – are available to download on L2 **

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Related Notes and Presentations on L2, including: New FAWG Manifests – Post ET Damage. Daily Ops Reports. NASA and Lockheed Martin Presentations on the ET damage (VAST AND DAILY), plus new images and many downloadable presentations. ET Manifest (Lockheed Martin) ET-117 Production Milestone Presentations, ‘through to’ STS-124 Baseline Mission Presentations, plus more, available to download on L2.

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Currently, the best estimated launch target for Atlantis remains late April, but planning documentation continues to reference the 45 day repair and certification plan that will be conducted in the VAB, which was outlined as one of the four manifest options for the refined launch date, listed – in this scenario – as NET (No Earlier Than) May 11.

During the referencing of a moisture level requirement on a Thursday United Space Alliance presentation, the 45 day stay in the VAB was once again listed as the current timeline the tank repair flow.

‘PLBD Drying: The 45 day VAB stay, coupled with the minimum 22 days required for pad processing, remain within the bounds for PLBD moisture requirements under the current conditions. Updates incorporating actual (past) data with projected 70 percent humidity will be performed each week.’

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Continued refinement is expected as repairs proceed, and another major meeting has been set for next week (on the 21st) to update the status of the timeline and repairs.

This meeting is required to further evaluate the ‘non standard’ repairs on the tank, which involves new foam being sprayed on to some of the damaged areas. Certification efforts will be focused on such repairs to ensure the tank would be safe to fly.

‘Group generally concurred with proposed methods for hardware assessment and repairs. Existing data, planned testing and demonstration were appropriate to support disposition and flight rationale,’ noted a summary of the TIM meeting, in a PRCB presentation on Thursday.

‘Actions issued to support verification primarily associated with residual risk of undetected crushed foam (ice and TPS debris) and LO2 tank repair flight history assessment – Includes correlation of STS-96 to STS-117 hail environments and additional assessment of STS-96 performance (debris due to undetected damage / ice).’

While a small level of repairs have already started on ET-124 – including the application of red dye to aid the assessment process and LO2 Ogive Foamtrim/sanding – the official go-ahead to proceed with full repairs on the tank has been given.

‘Team concurred with rationale to proceed with standard repairs (allowed per engineering). Dispositions in work. Repairs possibly starting Friday,’ added the presentation. ‘Additional data required for approach proposed for non-standard repairs (i.e. forward ogive demonstration / verification, damage < 0.25”deep) and undetected damage.’

This was an important milestone, given the opposing option – waiting for ET-117 to arrive from the Michoud Assembly Facility (MAF) in April – would have moved STS-117 to a June launch target. However, this “tank swap” option remains on the table.

MAF documentation shows that ET-117 will be ready for shipping at the end of March, for an April 4 arrival at KSC. The next tanks in the flow (ETs 120, 125, 126 and 128) are all on schedule.

Repair evaluation presentations have continued to be produced on a daily basis, as the plan to bring ET-124 back up to an acceptable flight status continue unabated. The latest presentations (Thursday) note an increased area that will be trimmed from the top of the LOX area of the ET, now reaching around 300 degrees of the circumference.

Further meetings are planned to discuss and evaluate the status of the repair effort, working on both the engineering and technical standpoints, as the assessment process refines the areas of damage that need to be repaired. A further 106 areas of damage were listed on Wednesday.

‘Senior Management Review scheduled for 3/21 to review approach for non-standard repairs and acceptance of undetected damage,’ noted the PRCB presentation. ‘Forward ogive repair technical data review tentatively scheduled for early April (week of 4/9).

Meanwhile, repairs on Atlantis’ left wing, which suffered a small amount of damage from the freak hail storm, are almost complete.

‘6 repairs remain needing repair,’ a United Space Alliance presentation on Thursday listed, which also noted the need for further access requirements. ‘Need high crew access. Platform installation to commence this week. Work scheduled for next week.’

Further articles will follow. Please refer to the live update pages on L2 (for NASA presentations, memos, emails and images) and on Atlantis’ section (open to all).

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