STS-132: Engineers successfully resolve hypergolic loading issues

by Chris Bergin

Pad operations continue to track a tight timeline ahead of the targeted May 14 launch, as engineers successfully worked through a number of Interim Problem Reports (IPRs) associated with the ongoing hypergolic loading operations on Atlantis’ stack. All eyes are now on next week’s Agency-level Flight Readiness Review (FRR), which will set the official launch date.

STS-132 Processing Latest:

It takes two to three days to complete the loading of hypergolics into the orbiter and Solid Rocket Boosters (SRBs). Due to the complexity of the operations, issues – listed as IPRs – are commonplace, especially when related to the Ground Support Equipment (GSE) used to transfer the extremely hazardous hypers into the vehicle.

The first issue to be cleared was IPR 0030, related to leaks in the Left Hand Aft Propulsion System (APS), found to be caused by flex hoses, which have since been replaced.

“IPR 0030 LH Aft Propulsion System (APS) fuel QDs MD421 and MD423 leaks: The flex hoses were found to be the source of the leaks. Flex hoses have been replaced and retested,” noted the NASA Test Director (NTD) in processing information (L2).

With that issue cleared, engineers picked up with S1287 operations – known as Orbiter Aft closeouts, while initial Aft Confidence instrumentation snap shots were completed. In support of hypergolic loading operations, Atlantis’ Payload Bay Doors (PLBDs) were closed to protect the STS-132 payload from potential contamination.

The skill and experience of the engineering teams then resolved four IPRs that were triggered during pre-launch Hypergolic Propellant Servicing – known as S0024 operations.

“New IPR 0031: Right Reaction Control System (RRCS) oxidizer tank could not be vented. Troubleshooting determined that Quick Disconnect (QD) MD 324 ground half was defective. Ground half QD was replaced, re-mated and successfully leak checked,” listed the NTD report on Friday.

“New IPR 0032: During servicing of the right Rock SRB Fuel Service Module (FSM), the fill QD picked up a visible leak while connected to the servicing cart bleed block. The QD was replaced and leak checked. SRB Hydraulic Power Unit (HPU) FSM loading was completed Thursday .

“New 0033: During IPR-0031 QD MD324 replacement QD MD524 was inadvertently de-mated instead of QD MD324. MD524 was re-mated and successfully leak checked.

“New IPR 0034: Slight oxidizer release when APS right RCS QD MD326 was closed. Cause is probable MD326 nose seal rolled when the QD closed. Troubleshooting completed successfully and Aft Propulsion System (APS) Oxidizer cross feed configuration was completed.”

With the successful resolution to all the IPRs, engineers will now press forward with a weekend of busy work, as May 14 – despite only having one day of contingency in the flow – remains a viable target for the launch date.

“Picked up a hyperload, will complete around midnight Friday night. After complete hyperload, will pick up with aft closeout this weekend. On track for launch on May 14,” noted KSC Ground Operations (L2).

“Weekend Work: Complete hypergolic propellant loading of the vehicle per S0024. Orbiter Aft Closeout,” added the NTD. “Crew Module hatch jettison T-Handle safing pin replacement. Install left pyro. canister and HI-POT electrical harness. Charge ET camera battery.”

SSP Flight Readiness Review (FRR):

Confidence in achieving a readiness to launch on May 14 was noted by Space Shuttle Program (SSP) manager John Shannon, who praised the teams involved in this week’s SSP FRR at the Johnson Space Center (JSC).

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“Thanks to the entire team for all the hard work prepping for the FRR. It went really well. Although the schedule is tight, and we have a lot of work still in front of us before we are ready to go fly, we are going to aim for the Friday, May 14 launch date. If things go well we should make that date.”

Five exceptions were noted during the meeting, which is expected based on the routine of carrying IFAs (In Flight Anomalies) over from the previous mission – as was the case with all but one of the aforementioned exceptions.

“All orgs polled go for proceeding to the Agency FRR on 5/5 and launch targeted for 5/14,” noted a summary of the SSP FRR findings, with 29 presentations from the FRR available on L2 (articles will follow in the run up to launch). “There were five exceptions logged, all of which are expected to be closed prior to the L-2 MMT (Mission Management Team).”

As reported, managers decided to advance STS-133 ahead of STS-134, due to the issues with Endeavour’s AMS payload, resulting in a delay to STS-134 to at least November. With Discovery advancing ahead of STS-134, she has become the LON (Launch On Need) support vehicle for Atlantis’ STS-132 mission.

“With delay of STS-134 to NET (No Earlier Than) November, STS-133 will serve as the LON for the STS-132 mission. ISS consumables support a September 16th LON launch date,” noted the FRR findings, backed up by FRR documentation that shows a very healthy CSCS (Crew Shuttle Contingency Support) level – the amount of time a stranded STS-132 crew could take up safe haven on the ISS – of 125 days.

Carried over from STS-131 was the on-orbit problems related to the Ku failure. With Discovery now back in her Orbiter Processing Facility (OPF), engineers have been able to repeat the failure and pinpoint the problem (more will follow at the weekend in a STS-133-specific article).

“Troubleshooting at KSC for the STS-131 Ku failure began on Tuesday and the failure was repeated,” added the FRR notes. “Indications are that the failure is in the Deployed Assembly (DA). It will be sent to (lab) for failure analysis.

“The MOD action related to the Ku failure on STS-131 will be closed at the 5/3 noon board (utilize same plan as STS-131 if Ku fails on STS-132 except that 3-D mode will be utilized for RCC inspections).”

As observed via Flight Day 2 and 3 inspection footage, Discovery lost a tile from her Rudder Speed Brake (RSB) during ascent.

As evaluated during the mission, the loss of TPS from this area of the vehicle held no impact to both the controllability or safety of the vehicle.

“The integrated In-flight Anomaly for the Rudder Speedbrake TPS liberation will be closed at the 5/4 SICB (Safety Integration Control Board),” added the FRR overview.

“Orbiter performed further analysis for liberation of one and two RSB tiles and concluded that although localized structural damage is possible, there is no issue with control or flight safety.”

More inspections will be carried out on the small ceramic inserts that surround the windows of the orbiter, following notes that STS-132 also suffered from liberated plugs.

Two areas of interest remain under evaluation, the first related to any potential downstream damage to the orbiter that may be caused by a liberating plug from the region of the windows, while flight history supports findings that any liberation from the Payload Bay Door hinges remains extremely unlikely.

“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 the FRR overview. “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). Presentation to noon board on Friday and discussion at 5/4 SICB.”

The final area of discussion referred to the pre-flight issue with the stuck helium isolation valve on the Right Reaction Control System (RRCS).

Following a Special PRCB (Program Requirements Control Board) meeting, and the subsequent debate at the STS-131 Agency FRR meeting, engineers and managers became confident that the system’s downstream regulators would provide the required amount of redundancy in the system.

They were proven right, with no issues reported on orbit with the RRCS pressure readings. However, a slight issue was observed on the L RCS helium isolation valve during the latter stages of STS-131’s mission.

As a matter of due course, engineers have checked the related hardware on Discovery’s two sisters, with Atlantis’ valves all deemed to be in fully functional condition.

“In addition to the right RCS fuel helium isolation valve stuck open preflight for STS-131, anomalies have been taken for the Left RCS helium B isol valve slow to close post-wave off and the Forward RCS helium A isolation valve slow to close during the post-flight valve test,” the notes added.

“Problem could be a valve problem or valve position indicator. IPRs have been opened for troubleshooting. All OV-104 (Atlantis) RCS helium isolation valve were verified functional this flow.”

The next two meetings for STS-132 will be the L-10 day Bench Review – or MMT STS-132 Prebrief/STS-131 Debrief – which will take place on Monday afternoon, followed by Wednesday’s key Agency FRR meeting at the Kennedy Space Center (KSC).

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