Endeavour into safing operations – Left gear brake fire investigated

by Chris Bergin

Following the conclusion to her flight career, Endeavour is now undergoing safing, ahead of being stripped of her numerous propulsion elements in preparation for shipping to her California retirement home next year. As managers review her performance, one item of interest relates to a small fire on her Left Main Landing Gear (LMLG) during rollout on the Shuttle Landing Facility (SLF) runway.

Post STS-134 Early Reviews:

Endeavour put the finishing touches to her honorable legacy, by leaving the International Space Station (ISS) – she helped build – in a good configuration for its long term future, along with installing the flagship AMS-2 particle physics payload to the outside of the orbital outpost.

In total, her mission was the 134th mission supporting the Space Shuttle Program (SSP), completing 4,677 orbits of Earth for a total of 122,833,151 miles and 299 days in space – as noted in a loving tribute via the normally technical NASA Test Director (NTD) report. 

(Animated image resized from hires/full screen version and sequence photo dumps on L2′s STS-134 Flight Day image section – several hundred megabytes strong.) 

“First launched in May 1992 on STS-49, career highlights include: the first 3-person EVA and longest since Apollo 17 (STS-49), the first Hubble servicing mission (STS-61), delivery of the Unity module to the Zarya module of the ISS (STS-88), 11 missions supporting ISS assembly and crew rotation; including delivery of the Kibo module (STS-123), Node 3/Cupola (STS-130) and, most recently, the Alpha Magnetic Spectrometer (STS-134) among many other significant contributions to our nation.

“Welcome home Endeavour! Thank you for your service to our country’s Human Spaceflight Program.”

Click here for Endeavour’s full history:
Part 1: http://www.nasaspaceflight.com/2011/04/space-shuttle-endeavour-a-new-beginning-part-i/
Part 2: http://www.nasaspaceflight.com/2011/04/ov-105-endeavour-a-long-standing-dream-realized/

Apart from the cosmetic damage to her Thermal Protection System (TPS) – which was ably cleared by the Damage Assessment Team (DAT) and the Mission Management Team (MMT) via a Focused Inspection (FI) – Endeavour’s performance on orbit was once again impressive.

Her final mission milestones, prior to coming to one final wheels stop under her own power, all went to plan, according to the Mission Evaluation Room (MER) post landing evaluation report (L2).

“The STS-134 mission was successfully completed with a landing at Kennedy Space Center (KSC), Florida. Both Payload Bay Doors (PLBDs) were closed nominally by 153/02:48:23 GMT [15/13:54:16 Mission Elapsed Time (MET)] in preparation for landing,” noted the documentation.

“The deorbit maneuver for the first landing opportunity at KSC, a dual-engine firing, was performed on orbit 248 at 152/05:29:03 GMT (15/16:32:35 MET). The burn was 158.3 sec in duration with a Differential Velocity of 298.4 ft/sec. The resulting orbit was 23.2 by 188.5 nmi. Entry interface occurred at 152/06:03:06 GMT (15/17:06:38 MET).

“The main landing gear touchdown occurred KSC runway 15 at 152/06:34:50 GMT (15/17:38:12 MET). The drag chute was deployed at 152/06:34:53 GMT. The nose gear touchdown occurred at 152/06:35:00 GMT. Drag chute jettison occurred at 153/06:35:19 GMT. Wheels stop occurred at 152/06:35:33 GMT. The rollout was normal in all respects.”

While the return was – as noted – normal, a later report noted Endeavour’s rollout down the SLF was the second shortest in the history of the Space Shuttle Program (SSP), notable not least because no Detailed Test Objective (DTO) into a “hard braking” test was requested for this landing.

A related investigation is also being carried out on observations of a small fire – lasting around 40 seconds on one of Endeavour’s Left Main Landing Gear – was observed at the end of the braking period as the orbiter came to a stop.

According to Kennedy Space Center (KSC) sources, the teams which greeted the orbiter noticed no indications of the brief fire during the runway inspections, nor did they find any truly discernible indications of a fire after they gave Endeavour a thorough inspection on Wednesday. 

It was only during reviews of the landing videos when it was raised to managers, leading to the investigation. Part of the review will be into the braking force applied during rollout, which is believed to have been somewhat “above normal”, given the second shortest roll out in the program.

The incident also impacts on Endeavour’s Transition and Retirement (T&R) processing, given the brakes on the orbiter were set to remain on the vehicle. It is now likely they will be removed to allow for a thorough investigation.

Currently, the two most likely causes are suspected to be excess grease on the wheel/axle or a leaking hydraulic puck, in tandem with the heavier than normal braking. Engineers are expected to recharge the hydraulic pressure and inspect for a puck leakage or any other hydraulic system leakage.

STS-134 Specific Articles: http://www.nasaspaceflight.com/tag/sts-134/

Such small fires have been seen on commercial airlines before, and it is understood the fire held no threat to the orbiter or her crew’s safety. Any increased temperatures from the fire would have felt like a tickle to Endeavour, given she had just raced through the thousands of degrees of heat during re-entry.

Had the fire of been larger, fire trucks would have left their staging point and been on site within seconds.

A full overview is expected at the Program Requirements Control Board (PRCB) level In Flight Anomaly (IFA) Review, scheduled for June 16 at the Johnson Space Center (JSC).

After coming to a stop, Endeavour – panting like a racehorse and breathing fire through her Auxiliary Power Unit (APU) vents near her Rudder Speed Brake (RSB) – was run through the post landing check-list by her crew.

This resulted in the sober sound of her three APUs being shutdown one by one, as the vehicle fell silent one final time.

The last APU was shutdown 20 minutes and 24 second after landing, which also concluded their successful use by Endeavour after the trouble caused by a heater system string pre-launch – while her total STS-134 flight duration was marked at 15 days, 17 hours, six minutes and 37 seconds.

After initial safing and integration with her oddball collection of convoy trucks, tow back to her Orbiter Processing Facility (OPF) began at 06:15 EDT on the morning of landing, arriving back into the arms of her engineering teams 75 minutes later.

Endeavour was then placed into S0069 Post Mission Integrated Roll-In Operations, which is an initial staging point ahead of the down-mission processing flow.

“S0069 Integrated roll-in operations are essentially complete. The left and right umbilical mates were completed along with GSE (Ground Support Equipment) connection to the Freon and Purge systems,” added the NTD reports for Endeavour’s post STS-134 flow.

“Fuel Cells were secured Wednesday at 14:32 EDT. Vehicle was Jack/Leveled with access platforms configured around the vehicle. PRSD (Power Reactant Storage and Distributation) residual cryo drain at 10:00 EDT (and now complete). Fuel Cell inerting complete.

“OMS (Orbital Manuvering System) QD (Quick Disconnect) access and scupper installation taking place Friday with trickle purge activation on Saturday. Payload Bay strongbacks installed Friday for opening on Monday afternoon. Weekend work: Aft access installation, trickle purge initiation.”

Endeavour will soon head into a schedule of T&R operations which will closely match her older sister Discovery, with the removal of her three Space Shuttle Main Engines (SSMEs) to be placed into storage for “potential” use on the Space Launch System (SLS) – pending a final configuration decision by NASA HQ (major article next week).

A total of 12 SSMEs – three flight sets and one spare set – are being saved for the SLS, a vehicle which is now heavily expected to be a form of Shuttle Derived (SD) Heavy Lift Launch Vehicle (HLV), allowing for a role in powering the new vehicle’s first stage during the opening flights, expected to begin in 2016.

The three orbiters are currently baselined to each receive three Replica Shuttle Main Engines (RSMEs) – made from previously scrapped nozzles and installed via an adaptor – for when the vehicles retire to their exhibitions.

Like Discovery, Endeavour will have both of her OMS Pods removed, along with her Forward Reaction Control System (FRCS), leaving a bare looking orbiter, prior to further replica replacements being installed.

The aforementioned propulsion systems will be shipped to the White Sands facility for deservicing and safing, with Discovery’s FRCS current in the Hypergolics Maintenance Facility (HMF) in preparation for its trip to New Mexico.

(Images via Larry Sullivan – MaxQ Entertainment/NASASpaceflight.com, L2 Content and NASA.gov. Post STS-134 coverage of Endeavour is continuing in L2, which will follow Endeavour all the way to her retirement home in California).

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