Cold weather delays STS-130 pad flow – Right SRB undergoes troubleshooting

by Chris Bergin

Hypergolic loading of the STS-130 stack has suffered a slight delay due to unacceptable temperatures at Pad 39A, allowing for troubleshooting to take place with the Hydraulic Power Unit (HPU) on the right boosters. Endeavour is still tracking a February 7 launch date, although the schedule is tight, due to two Node 3 ammonia line solutions that are in work.

STS-130 Processing Latest:

With vertical payload pre-operations are scheduled to begin on Thursday, leading to payload transfer activities scheduled for Friday, Endeavour continues to be in a good stance to launch on February 7 – despite a couple of problems at the pad.

The first issue is out of the control of the talented engineers at the Kennedy Space Center (KSC), as cold weather delayed the loading of hypergolics into the STS-130 stack.

“Due to the cold temps experienced at KSC, HPU and APU (Auxiliary Power Unit) propellant temps were too low yesterday morning to begin flow,” noted Wednesday processing information on L2.

“APU and engineering developed a plan yesterday to direct warm purge air to the APU/HPU carts overnight in hopes of raising the temperature of the fuel. OMS Oxidizer load is scheduled for today as temperatures allow, and will be followed by OMS and APU fuel early Thursday on 3rd shift.

“HPU fuel load SCAPE (Self-Contained Atmospheric Protection Ensemble) operations will now be performed Thursday mid 1st shift. The team made the decision to stand down from loading operations for Tuesday to allow HPU to troubleshoot IPR-0036/37.”

This hardware issue – which has nothing to do with the cold weather – relates to the right hand booster, with pressure on the HPU’s Right Rock and Right Tilt FSM (Fuel Supply Module) suffering from a pressure drop/leak – which required troubleshooting.

There are two self- contained, independent HPUs on each SRB. Each HPU consists of an auxiliary power unit, fuel supply module, hydraulic pump, hydraulic reservoir and hydraulic fluid manifold assembly. The two separate HPUs and two hydraulic systems are located on the aft end of each SRB between the SRB nozzle and aft skirt.

A2The HPU components are mounted on the aft skirt between the rock and tilt actuators which steer the boosters and the vehicle. The two systems operate from T-28 seconds until SRB separation from the orbiter and external tank. The two independent hydraulic systems are connected to the rock and tilt servoactuators.

“(Right Rock pressure) from 124 PSIA to 24 PSIA since last power up (approx. 38 hours). Initial troubleshooting plan is to include greasing QD (Quick Disconnect) and cycling. Engineering evaluation is underway. Constraint is to Fuel Load completion, S0024.000,” noted processing information on L2.

“HPU: Right Tilt FSM pressure dropped from 127 PSIA to 106 PSIA since last power up (approx. 38 hours), (same troubleshooting and constraint note as per Right Rock).”

Good news was reported on Wednesday, when the NASA Test Director noted the Right Rock leak had decreased via initial troubleshooting, with work on the Right Tilt set to take place on Thursday.

“IPR 0036 (Right Rock FSM pressure decay) update: The leak rate has improved significantly as a result of troubleshooting performed yesterday, however there is still a small amount of leakage noted during bubble-soap leak checks. HPU is monitoring pressures and will determine if further troubleshooting will be required,” noted Wednesday processing information.

“IPR 0037 (Right Tilt FSM pressure dropping) update: Troubleshooting was rescheduled to Thursday.”

Flight Readiness Review:

Managers are continuing their preparations for the two main Flight Readiness Reviews (FRRs) that will review the status of STS-130 and set the launch date. The Level II Space Shuttle Program (SSP) FRR is scheduled for January 19th and 20th, while the Level I Agency FRR on January 27th will set the launch date.

Numerous departmental FRRs are already taking place ahead of the two day SSP FRR, while the Mission Operations Directive (MOD) review – 12 presentations available on L2 – has been completed.

STS-130 Specific Articles:

“We conducted the MOD Flight Readiness Review on January 7th. Excellent job by the entire MOD team to prepare for this significant milestone,” noted MOD’s 8th Floor News internal memo on L2.

“This mission installs Node 3/Cupola to the Node-1 port location, relocates the Cupola to Node-3 Nadir, and relocates PMA-3 from Node-2 zenith to the Node-3 port location. This mission also launches the Distillation Assembly, which is expected to recover waste processing capability in the US segment.”

A4The 8th Floor also noted the ongoing work to protect the February 7 launch date, following the rupturing of ammonia lines associated with Endeavour’s Node 3 payload.

“The most significant concern with flight readiness is the issue with testing of the ammonia hoses to be used to integrate Node 3 into the existing ISS thermal control system. Failures have occurred during qualification testing, which bring into question as to whether the hoses are acceptable. The ISS Program has organized a tiger team to fully investigate the issue.”

At Tuesday’s SSPCB (Space Station Program Control Board) meeting, the Tiger Team’s two main solutions – the primary being the welding together of several smaller spare NH3 lines to create a “Franken Line”, and a secondary back-up of beefing up the existing lines – were approved to proceed towards completion.

Engineers hope this will continue to support a February 7 launch date, though more will be known by next week as the schedule is tight. Regardless, this is a major turnaround from the initial fears of a shortened mission, and even a swap in the mission order.

“MOD is participating in the evaluation of various options that are under consideration, such as delaying launch if necessary to ensure the hoses are properly designed and built and updating mission requirements if the hoses aren’t launched on STS-130,” added the Jan 12 8th Floor update.

“As these options are considered, MOD’s main focus needs to be the nominal plan to ensure we are ready for a February 7th launch. So stay focused as the data leads us to the right decisions.”

L2 members: Documentation – from which the above article has quoted snippets – is available in full in the related L2 sections, now over 4000 gbs in size

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