STS-132 heads into Agency FRR – Ku-band root cause found
NASA and contractor managers will set STS-132’s launch date during the Agency level Flight Readiness Review (FRR) on Wednesday. No major issues have been noted, while Atlantis continues to behave on Pad 39A, raising the likelihood May 14 will be set as the launch date. Meanwhile, engineers have pinpointed the cause of Discovery’s Ku-band system issues, observed during STS-131.
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Mirroring recent flows, Atlantis continues to enjoy a low IPR (Interim Problem Report) count, with only 37 issues being noted since she returned from STS-129. Notably, all recent IPRs have related mainly to Ground Support Equipment (GSE) as opposed to Atlantis herself.
“S0024 Pre-launch Hypergolic Propellant Servicing was completed over the weekend. Orbiter Midbody Umbilical Unit (OMBUU) mate was completed Monday,” noted NASA Test Director (NTD) processing information (L2).
“New IPR 0035 to OMS (Orbital Maneuvering System)/RCS (Reaction Control System). During Right Orbital Maneuvering System (ROMS) fuel tank fill the tank ullage pressure failed to be maintained. Current-to-Air transducer on a Ground Support Equipment (GSE) flow control valve failed. The transducer was replaced and ROMS tank loading continued.
“New IPR 0036 to APU (Auxiliary Power Unit). During Auxiliary Power Unit (APU)1 GN2 pressurization, QD (Quick Disconnect) MD12 Airborne Half Coupler (AHC) failed leak check and the GN2 tank pressure increased. The QD was cycled 3 times, and leak rate improved enough that APU pressurization was able to continue.
“New IPR 132V-0037 to OMS/RCS. During post Forward Reaction Control System (FRCS) fuel load, QD MD121 was leaking internally. An extended decay check on the QD was performed which verified the AHC leak rate was acceptable. FRCS fuel load was continued.”
A previous IPR (0029) – related to troubleshooting on a Partial Pressure Oxygen (PPO2) sensor C – ruled out the amplifier and sensor as culprits for the failure to calibrate. As such, troubleshooting results remain under evaluation.
The main aim of the flow this week is to prepare for Launch Countdown operations, known as S0007. Despite only one contingency day available in the flow, engineers remain on track to hit their target, allowing for the first launch attempt to take place on May 14.
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“S5009 Ordnance Installation completed. The vehicle is powered up and personnel are being cleared from the pad for post ordnance installation testing. Orbiter Aft closeout continues. Door installation for flight is planned for Friday,” added NTD processing information.
“Payload Bay Doors were re-opened to support bulb seal repair which is complete less 72 hour cure. Latch guide installation started today and will be finished after ordnance installation. Remote Manipulator System (RMS) elbow camera installation has been rescheduled.
“S0007 Launch countdown preps are in work and will continue through the week.”
STS-132’s Agency (SOMD) FRR is not expected to have any major talking points, thanks for the smooth flow of what is currently Atlantis’ final mission on the schedule. With all departmental FRRs now complete, the Agency FRR will set the launch date, ahead of follow-on reviews by the Mission Management Team (MMT).
“Agency FRR charts are due for the FRR on Wednesday that starts at 8:00 a.m. ET. The MMT pre-brief and STS-131 debrief (were conducted on Tuesday),” noted the KSC Integration manager on the latest Shuttle Standup/Integration report (L2), which included a late note on Atlantis’ Californian landing option.
“At Edwards (Dryden Flight Research Center), the main runways are back up. The Air Force will transition Ops over next weekend. Have both the Microwave Scanning Beam Landing Systems (MSBLSs) on 22 left and 04 right up and certified to support STS-132.”
As with all FRRs, the previous mission’s IFAs (In Flight Anomalies) make up a large part of the discussions, resulting in Discovery’s Ku-Band failure – and plans for any re-occurrence with Atlantis – being added to the meeting.
“On the Ku-band failure, the robotics instructors have tagged up with future crews to offer additional training for the docked inspection,” noted Flight Operations on the Standup report. “Feedback from the crews is that they feel they have been adequately trained and are in good shape should there be another failure.”
Charged as Discovery’s fourth IPR for her STS-133 flow, troubleshooting on her Ku-band hardware began shortly after she arrived back into the Orbiter Processing Facility (OPF-3), following the conclusion of STS-131.
“IPR-0004 Ku Band troubleshooting is Complete to Date. Ku band is still not functioning properly. Engineering is evaluating. More troubleshooting will follow,” noted the opening set of processing notes on the evaluations.
“Ku Band troubleshooting is complete to date. Verified that the 156 MHz reference signal was good going into the Deployed Assembly (DA). Signal was steady and had a good level. Tentative plan is to replace the DA.”
Over the weekend, engineers were planning to replace the DA on Discovery’s Ku-Band system, although this operation is currently on hold pending a decision on which spare DA will be installed on the veteran orbiter.
“The Ku-Band removed from OV-103 (Discovery) was received at the (Lab) Saturday morning. The team worked through the weekend troubleshooting. Isolated the failure to a Q6 transistor on harmonic phase comparator on the same exciter with the DEA. It was isolated to the DEA,” added KSC Logistics on the Standup report.
“That data will be turned over to the Engineering team for additional troubleshooting.”
“The last Ku failure was STS-92, and was a Q5 transistor. Was a different location, but the same transistor,” added the Orbiter Project Office (OPO) on the Standup report, who also referred to another ongoing topic for FRR discussion – the small ceramic inserts that have become a liberation issue during recent flights.
“The team working the SICB (Safety Integration Control Board) and ceramic inserts are working long hours and putting in a lot of overtime. Pulling a story together this quickly is impressive. Kudos to that team; they are doing an amazing job.”
Given previous discussions ahead of STS-131, this topic is very unlikely to be a problem for the FRR. However, further actions have been noted via the inspection and replacement procedures, while flight history continues to play a positive role in easing concerns relating to potential liberations from the Payload Bay Door hinges.
With all areas of liberation, potential impacts to downstream hardware is a concern that remains under constant evaluation.
“More discussion to come on window fasteners since STS-131 post-flight inspections determined one missing plug on window 6 and two protruding plugs on windows 5 and 6,” added pre-FRR notes (L2) from MOD’s 8th Floor (L2).
“Plan is to inspect and reinstall all plugs that have potential to come loose. As discussed prior to STS-131, the payload bay hinge line locations are not accessible at the pad. Only one plug has been liberated in our flight history – occurred on base of vertical tail (two other occurrences of loss of the insert/plug which is different failure mode).”
With the Rudder Speed Brake (RSB) tile liberation during STS-131’s launch also cleared via reviews, Space Shuttle Program (SSP) manager John Shannon noted his pride for his teams, referencing Associate Administrator for Space Operations) Bill Gerstenmaier’s acceptance speech at a recent award ceremony.
“The National Space Trophy was won by Bill Gerstenmaier. In his acceptance speech, he thanked the Space Shuttle team effusively for how much this team has done over the last several years to keep the Program on track and operating as safely as we have been. He really meant that,” noted Mr Shannon on the Standup report.
“The team is doing an amazing job of getting all of the issues turned around and all of the proper discussions. We are rolling into next week in good shape (Mr Shannon) agreed with the kudos. There was lots of good feedback on how great this team is doing. Keep it up, and we will see most of you down in Florida (for the FRR).”