Pad 39A repairs move to spray mode – STS-125 ET/SRB mate delay

by Chris Bergin

Engineers repairing damage to the flame trench at Pad 39A have started to spray Fondue Fyre into the damaged areas of the concrete wall – and remain on track to have the pad ready to accept Atlantis in time for the October launch of STS-125.

Meanwhile, the schedule date for Atlantis’ External Tank (ET-127) mate with the twin Solid Rocket Boosters (SRBs) has taken a three day hit, due to replacement work on a damaged valve on the tank.

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Over in OPF-1 (Orbiter Processing Facility) Atlantis is moving towards the closure of her Payload Bay Doors (PLBD) this coming weekend, as her flow remains issue-free.

“SSME carrier panel installations should be completed by today. Hubble Space Telescope mid-body highly sensitive cleaning continues through this week,” noted Tuesday processing information on L2. “Orbiter and OMS closeouts for flight continue this week.

“Wing leading edge sensor battery installation/checkout was performed on Monday and continues today. Master timing unit oscillator frequency adjust call to stations occurred yesterday and will be worked through Wednesday.

“Final Ku-band antenna self test will be performed today. Completed Inertial measurement unit (IMU) checkout and calibration yesterday. GPS battery R&R occurred on Monday. Scheduled to perform GPS functional today. Payload Bay Door closure is targeted for Saturday.”

As managers prepare to discuss the possibility of moving the launch date up next month, to as much as October 2 for STS-125 – in order to hand flexibility to STS-126’s launch window in November – work in the Vehicle Assembly Building (VAB) has taken a small hit from the work required to replace a damaged GH2 valve on Atlantis’ ET-127 tank.

“Foam application and trimming continues. GH2 2 inch disconnect repair preps and foam removal are in work. Engineering is evaluating the forward plan,” noted Tuesday processing latest from the VAB’s High Bay 4 checkout cell, where the tank is located.

“ET/SRB mate is now planned for August 2, due to the 2 inch disconnect valve work. An ET/SRB mate review is scheduled for Friday, July 25.”

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A three day hit to the mating operations for both ET/SRB and Orbiter, will be covered by contingency days at the pad, with regards to the current October 8 launch date target.

“On ET-127, still tracking to 15-day plan. Picked up an issue on the 2 inch GH2 disconnect. The decision was made to R&R that. Over the weekend, started removing the foam from around that disconnect,” added the latest Shuttle Stand-up/Integration report.

“Expect Boeing team to be at KSC on July 24 to take up with the 2 inch disconnect work and also the angle and tip load. The disconnect issue will probably be a three-day serial impact to ET mate and orbiter mate, but have contingency time at the pad they’ll use to make up for STS-125 flow.”

All ETs are housed in the checkout cells after arriving from the Michoud Assembly Facility (MAF), where they are fully inspected after their five day barge journey.

Any work that is required to be carried out, can then place ahead of ET/SRB mate – and in the case of ET-127, this includes the possible correction of a few minor scuffs that have been found on the tank.

“Engineering is evaluating scuffed Helium braided flex line and 3 voids in foam,” added the processing report. “LH (Left Hand) Vertical strut TPS (Thermal Protection System) Anomaly Bucket (completed. LO2 feedline to crossbeam foam repairs are complete and in closure.

“PDL (foam) pours planned for today: LH2 AFT dome, RH Vertical Strut, and LH2 Recirc line.”

Pad 39A Repair Status:

Engineering work at the pad has been proceeding extremely well, despite the challenge of repairing a flame trench that liberated literally thousands of bricks during Discovery’s STS-124 launch.

A multi-phase approach has been undertaken by various contractors, who have completed the removal of unstable bricks that remained in the wall. This was followed by hydroblasting the walls in order to remove residual epoxy.

To firm up the structure ahead of the coating of Fondu Fyre, the installation of additional anchors and plates took place to secure voids found during tap tests.

Heavy rain in the KSC area, along with stubborn epoxy residue, has failed to delay operations that are now moving into Phase II of the repair, with the follow-on contractor (Metcon) – who have started around the clock repair activities.

“Phase II, includes anchoring and installation of the Fondu Fyre material. The Phase II effort is scheduled to be completed by 8/11/08,” noted a previous status report on the repair process.

“The contractor started to locate rebar on the East wall to allow drilling of holes for the wall anchors. Rebar location of the East wall was completed on Wednesday and West wall should be completed on Thursday of last week. Fondu Fyre materials, wall anchor bolts, and steel grid sheets arrived mid-week.

“The existing vertical “dovetail” steel channels require additional corrosion removal before the Fondu Fyre is applied. The Fondu Fyre contractor arrived Monday (Yesterday) morning and prepared for spraying applications.

“Severe Weather initially delayed the start of the Fondu Fyre application yesterday (Monday), but the contractor picked up spraying both East and West walls shortly after the weather passed.”

Fondu Fyre – a concrete material – has remained the only refractory material qualified for use at KSC, and that performance during the program has been satisfactory, with increased maintenance and process modifications.

The material’s performance has managed an average of five launches between major maintenance/refurbishment, along with modifications to the material over the history of the program.

It was chosen as the preferred repair option not long after the pad damage was evaluated by shuttle managers..

“1. Rebuild the Flame Trench wall system per the original design (complete or incremental): Known design and performance. Large demolition requirement complicated by Asbestos removal. Long lead times for components,” noted a presentation on the downselected repair method.

“2. Rebuild the Flame Trench wall system utilizing Fondue Fyre similar to what is used on the Flame Deflectors (complete or incremental): Known design and performance, though much larger application. Large demolition requirement complicated by Asbestos removal. Short lead times for repair.

“3. Apply Fondu Fyre over top of the existing wall system (complete or incremental): Unknown performance due to state of wall system. Small demolition requirement to remove loose bricks. Short lead times for repair.

“4. Use as is was not considered due to the damage which would occur to the main concrete structural wall currently exposed.”

“Recommend Option 2 Partial with Risk Mitigation B. Repair all severally eroded areas + damaged area: Bottom 25′ (East/West Wall). Meets Flight Safety and Program objectives. Confidence that repair will be successful.

“Design will be certified against defined environmental loads. Similar configurations successfully used at Pads A and B throughout Shuttle program. Monitor and evaluate after each launch. The Recommended repair approach (partial spray with Fondue Fyre) will support the current manifest.”

Another note of interest is the pad will be kitted out with new sensors, embedded into the flame trench. It is not known if all the sensors will be installed in time for STS-125’s launch, but the long-term plan is set.

“An Engineering Review Board (ERB) was held to status the team on the progress of the design for instrumenting the flame trench,” noted associated information. “Several locations have been identified as likely candidates for installing sensors.

“The team thinks that some instrumentation can be implemented in time to support the STS-125 launch. Additional sensors may be added for subsequent launches.”

The application (spraying) of the Fondu Frye is expected to be completed by the end of the month, which places the completion of the pad’s repair on August 11.

“At Pad A, the flame trench activity is proceeding extremely well. Have the anchors installed in both the east and west walls. The grid steel system installation is continuing,” added the latest Stand-up report.

“We will begin the refractory application. On track to be completed by August 11.”

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