Atlantis suffers slight damage to radiator – FCV plan eases for STS-125

by Chris Bergin

Managers are close to approving a switch to an advanced May 11 launch date for STS-125, as engineers evaluate damage to Atlantis’ left radiator panel, following an impact from a torque wrench socket. Meanwhile, it has been decided to defer the modification of a doubler plate to the downstream Flow Control Valve (FCV) lines, until after STS-125 and STS-127.

STS-125 Pad Flow Latest:

The Hubble servicing payload has been successfully installed into Atlantis’ Payload Bay and is currently undergoing battery charging, as the pad flow remains on track for either a May 11, or May 12 launch date.

“S0600 vertical payload operations: Payload installation into Orbiter was completed on Wednesday,” noted Thursday morning processing information on L2. “Payload battery connector mates complete, battery charging in work. Orbiter Mid-body Umbilical Unit (OMBUU) mate is scheduled for today.”

As reported by this site on Tuesday, managers are attempting to move the launch date to May 11 in order to allow for three launch attempts, prior to handing over the range to the next Delta IV launch. The latest status noted the possibility of moving up the launch date is promising, with only a few “boxes to tick” until it could become official.

Launching earlier is also desirable, due to the short turnaround time ahead of Endeavour’s STS-127’s planned launch the following month.

However, a smooth pad flow between now and launch is required, with tTwo issues currently being worked by engineering teams, relating to the Camera/Flash system located in Atlantis’ ET Umbilical Well and damage to her left radiator panel – as noted on Thursday morning processing information on L2, along with hi res images.

“A 1 1/8” socket from a torque wrench fell from the PCR (Payload Checkout Room) level 4, impacting the Orbiter Port Aft Radiator,” noted the processing update.

“The impact point is approximately 5.5 inches forward of the trailing edge of the aft port radiator and approximately two inches out from the inboard edge of the radiator.”

a217An investigation into both the incident and the damage is taking place. Such accidents are possible when the tether – which stops the socket from falling any great distance – fails

Importantly, the impact managed to avoid one of the Freon loop lines which run through the radiator panels and allow for heat to be dispersed from the orbiter whilst on orbit. It also managed to miss the newly installed HST payload.

“Inspections have revealed the impact point was in between two Freon lines striking honeycomb material and causing no damage to the Freon lines,” added engineering notes on Thursday. ” The payload was not impacted in this incident. Engineering inspections and evaluation continue. Constraint is to vehicle power up.”

It is possible that no repair will be called for until Atlantis returns home to her Orbiter Processing Facility (OPF) after the completion of STS-125. Had the impact occurred on one of the Freon loop lines, repairs would have been required – likely leading to a delay in the launch date.

See also: Endeavour: MMOD hit to radiator
See also: Atlantis: MMOD hit originated from another vehicle

FCV Latest:

One of the other milestones in STS-125’s pad flow relates to the installation of Atlantis FCVs, which have been “cherry picked” for this flight as part of the short term mitigation plan for avoiding pieces of the valve’s poppet lips from liberating – as observed during STS-126.

Click here for articles on the FCV issue since STS-126.

a314Because one of the threats to a liberating piece of FCV is the potential puncturing of line at the 90 degree elbow bend – which is located immediately downstream of the valves – engineers have been working on a doubler plate, which would be installed to add protection to the line.

That plan is now likely to be initiated for future flights, but not for STS-125 or STS-127 – which some engineers favored – after it was decided to defer the installation until at least STS-128 with Discovery.

“The FCV manifold elbow doubler discussion was discussed and the decision was made to not pursue that for STS-125 and STS-127,” noted engineering logs on Thursday morning.

The installation of the FCVs is set for completion by the end of the month, which is well within the requirement for advancing the launch date to May 11.

STS-400/127 Pad Flow Latest:

Over on Pad 39B, Endeavour continues to be processed without issue, as she is prepared for her STS-400 Launch On Need (LON) support role for Atlantis’ STS-125 mission. Following the standdown, Endeavour will be moved to Pad 39A for her primary STS-127 mission.

“Engine and aero surface flight readiness testing (V1046), Ball Seal leak checks, and helium signature tests continue through tomorrow,” noted Thursday morning processing information on L2.

“Preparations for Prelaunch Propellant Servicing (S0024) began yesterday and continue into Saturday. Propellant load picks up on Monday with Call to Stations at 2200 EDT. OMBUU mate is scheduled for tomorrow. Crew compartment hatch functional was completed yesterday.”

“Launch Countdown Simulation (S0044) was successfully completed yesterday.”

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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