Exploration Ground Systems, Jacobs practice building SLS boosters in the VAB

by Philip Sloss

NASA Exploration Ground Systems (EGS) and prime test and operations contractor Jacobs are busy practicing how to put Solid Rocket Boosters (SRB) together in High Bay 4 of the Vehicle Assembly Building (VAB) at the Kennedy Space Center (KSC) in Florida. Working with inert motor segments and booster hardware, the EGS and Jacobs team are running through all the procedures they will use to process the SRB flight hardware for the first Space Launch System (SLS) launch, Exploration Mission-1 (EM-1).

The practice and training events cover the different procedural checklists the workforce will step through and the different KSC facilities where the Orbital ATK boosters will be processed once they arrive from Utah.

Jacobs provides operational support for all EGS launch processing activities and is prime for their test and operations support contract (TOSC). Along with EGS, their personnel are getting hands-on training by practicing with the ground support equipment and flight-like hardware in High Bay 4.

“Fundamentally, in order to get our workforce in a position where they’re trained and ready to support we try to establish things like these. We’ll have either a pathfinder event or we’ll have ourselves a training event,” David Diaz, NASA Operations Manager for Integrated Flow, said in an interview with NASASpaceflight.com.

“We try to use as much flight hardware — old flight hardware — as possible. So what did here was we were able to acquire, working with our different flight elements, we were able to acquire these particular parts from the booster [office].”

“This is where we train our technicians for hands-on touch labor, engineers are getting trained up on move director certification, so we’re getting a lot of our young Jacobs engineers, technicians, and crane crew all trained,” Kerry Chreist, Jacobs Flow Manager for the Rotation, Processing and Surge Facility (RPSF), added.

“This is a training event that trains not only the technicians [and] engineering [personnel], it also trains our quality [control], [and] it also trains our safety people [for] what we’ll be experiencing during the EM-1 processing.”

EGS Jacobs TOSC technicians working at the tang end of a bare metal booster cylinder. Credit: NASA/Glenn E. Benson

“This is a win-win training situation [for] brushing off the processes and procedures that we’re going to be doing during the EM-1 processing,” Chreist continued.

We’re conducting the same processes in training that we’ll be doing for EM-1. Some of that is the tang inspection, O-ring [inspection]. [After] joint mate we’ll be doing the test procedures for joint leak tests to make sure that we have a tight joint and that we’re not leaking past the O-rings. So we’re doing everything possible to simulate everything that we’ll do when we actually process the flight hardware.”

The team is working with two booster segments and two empty, bare metal cylinders that would make up the outside of segment. “Basically what creates that big segment is two individual cylinders, we have those. We can pretty much use one of the cylinders to mate it to the aft assembly, which is up in our buildup stands in the High Bay 4,” Diaz explained. “And then other direction, we’ll go ahead and get the center segment we’ll mate that to the other cylinder, it kind of gives us both ends.”

Looking up at the inert aft assembly in the build up stand in High Bay 4. Credit: NASA/Kim Shiflett

An outfitted aft assembly, with an inert aft segment, aft skirt, and nozzle extension, is configured in one stand in the high bay and an inert center segment is also there for the practice stacking activities. “This is actual one-time flight hardware, so it gives us a very flight-like environment for our TOSC workforce to go do their training and certification programs,” Diaz added.

The material in the inert segments is cast so that they have the same weight and balance characteristics as flight segments.

Ground Support Equipment: cranes, beams, stands and stations:

Outnumbering the booster rocket hardware in High Bay 4 is all the ground support equipment needed to inspect and prepare the segments to be attached to each other, and finally to move them into High Bay 3 for mating. “We basically have four stations set up there in the high bay that we’ll be using in the booster stacking when we do EM-1,” Chreist noted.

The segments are brought into the VAB sitting on a pallet. “This is how we transport it back and forth from the RPSF to the VAB when we’re ready to start processing of the hardware,” he explained. The pallet is picked up by a transporter in the RPSF and then lowered down after arrival in the high bay.

From left to right: bare metal cylinder, aft assembly in build up stand, one resting ‘384’ beam, another ‘384’ beam attached to the VAB 325-ton crane and the other empty cylinder, inert center segment sitting on a transportation pallet in High Bay 4. Credit: NASA/Kim Shiflett

Cranes lift and move large, massive hardware around the VAB. For booster hardware, a crane first attaches to a lifting beam that is then attached to a segment. “It’s called the 384 beam,” Chreist said. “That’s the beam that we actually hook up to the segments and move them around, both in the RPSF and we’ll be doing that in the VAB.”

The segments are connected at a tang/clevis field joint, with bottom, tang end of one cylinder lowered down onto the top clevis end of the other; pins around both circumferences then fasten them together.

The 384 four-point lifting beam has a similar tang interface to allow it to attach to the top, clevis end of a segment for lifting. There are two tangs at each of the lifting beam’s four quadrants where they are pinned to the segment.

Close-up of how the four-point ‘384’ lifting beam attaches to the top of a booster segment cylinder. Credit: NASA/Glenn E. Benson

After the beam is attached to the segment, it is lifted over to another workstation. “That’s station 3,” Chreist noted. “We lower the segment and put it down on there and what we can do is we can prep the tang, we do the inspection for the O-rings, we re-grease it and we prep it prior to doing mating operations.”

“We cannot prep it when it’s on the pallet, we have to pick it up and then we prep the joint,” he continued. “We pick it up and we’ll rotate it and then we get the joint completely prepped before we go, we call it going up and over, and get it ready for mate practice.”

At the beginning of the year, the team was using one of the bare metal cylinders to practice mating the field joint between the cylinder and the aft assembly. More recently, workers have been practicing with the other cylinder and the inert center segment at station 2. “Station 2 is where we have the ‘400’ stand, the work-stand, and we have a [bare metal] cylinder segment sitting there on that,” Chreist said.

The workstand with the empty cylinder is located on the floor in High Bay 4. Workers are practicing attaching the crane and a 384 lifting beam to the top of center segment, inspecting and preparing the bottom for mating, and then lifting the segment on top of the empty cylinder on the 400 stand and mating them together.

After the booster segments are physically fastened together with hundreds of pins around their circumference, the field joint is closed out with cork and room temperature vulcanizer (RTV) to protect the joint from the outside environment before and during launch. Those have to be applied to the joint in a controlled environment and so before each segment is lifted into High Bay 3 for stacking, it has essentially a rolled up, clear plastic tent — an environmental enclosure — attached around the bottom.

“It’s basically a shielding of the environment,” Chreist explained.  “The humidity is controlled and the temperature is controlled. Basically what we do is we set up the enclosure prior to the joint mate, then we go ‘up and over’ [and] we do the mating process,” he continued.

The rolled up plastic environmental enclosure, as seen around the bottom end of a Shuttle booster segment being lifted in the VAB Transfer Aisle in 2004. Credit: NASA

“Once the segment is lowered into place, the enclosure is unrolled down around work platforms surrounding the field joint area and sealed up for air conditioning.  Then the rest of the enclosure is sealed up and what we do is we environmentally control this — for humidity, temperature, and everything for joint closeout and also for the bonding of the cork and the RTV.”

The plastic itself is not critical for practicing the process of mating the hardware, but Diaz noted the team will practice some of the pre-lift work with it. “We will have set up — simulated [the] set up of — the actual enclosure structure and wrung out the plastic,” he said. “We just won’t be up on the platform, so we would have V&V’d it that way.”

As seen following set up for Shuttle booster segment mating in 2004, the plastic enclosure is draped over a work platform where the two segment are brought together. Environmental controls can be applied to create a clean room area. Credit: NASA

In addition stacking activities, the team is also practicing the reverse, destacking procedures. For the recent practice with the center segment, the practice is valuable, but the destacking is mandatory. “After we mate the joint over in High Bay 4, [where] we’re doing the segment mate training, we have to do a destack because cannot leave it on the 400 stand, we cannot leave that segment sitting on top of that cylinder,” Chreist explained.

“So what we do is we leave the crane attached, we do the joint mate, we do a leak check, and then at the end of the day what we do is…a de-pinning operation and take that segment back to the pallet. At night it is sat back on the pallet and the crane with the 384 beam is disconnected and everything is going to a resting place until we pick up [practice] at another time.”

RPSF practice:

The stacking practice in High Bay 4 is one in a series of training and certification events that EGS and Jacobs are performing ahead of EM-1 booster processing. The RPSF is one of the first stops for the booster’s motor segments when they arrive from Orbital ATK’s manufacturing and production facilities in Promontory, Utah.

Prior to the current activities, build up of the aft assembly provided the workforce with an opportunity to go through the procedures they’ll perform on the two flight assemblies next year in the RPSF.

“Back in about 2016, we went off and did what’s called an RPSF pathfinder effort,” Diaz explained. “Basically we took the whole processing flow for the RPSF, very similar to what they’re doing with the stacking operations in the VAB, and wrung out all our processes, all our paper, all our plans, what we planned to do. And that point is where we ended up using this aft segment in a build up.”

“We put that in a build up stand and we basically built that up there, wrung through our processes,” he continued. “We also were able to V&V (verify and validate) the [platform] development efforts — they did some modifications to the platforms due to the wider nozzle. So we got that all done and [that] was a mock up that TOSC went ahead and fabricated based on the drawings.”

Completed inert aft assembly in the RPSF, December, 2016. Credit: NASA

“Once we had the segments over at the RPSF we tested out our SRM transporter, we did…our route verification for EM-1 of how we were going to bring it around to High Bay 4,” Chreist added. “So we did a lot of training at the RPSF, not only the reactivation of the facility and certifying that the facility was ready to support the program.

“We conducted all the training for the Jacobs employees on both engineering, safety, quality, to hands-on flight technicians, so it was a win-win for the program there, so we’ve checked the box on there that the program is ready to support at the RPSF when the flight hardware is ready to arrive.”

Stacking flight hardware:

The iconic VAB is primarily divided into four high bays or cells, two “integration” cells facing east towards the launch pads and the Atlantic Ocean, and two facing to the west.

The cells are divided by a transfer aisle which extends to the south into a Low Bay. Exploration Mission vehicles with SLS launchers and Orion spacecraft will be stacked on a Mobile Launcher in the north east cell, High Bay 3.

Placard as seen entering the VAB in 2012. Cranes will lift the fully prepped booster segments up sixteen stories where they can cross from left to right in the diagram, going from High Bay 4 to High Bay 3. Credit: Philip Sloss for NSF/L2.

Space Shuttle vehicles — SRBs, External Tanks, and Orbiters — were stacked in the east side cells, High Bays 1 and 3. Generally all of the hardware was received or staged in the transfer aisle to be lifted into the high bays; booster segments would be transported from the nearby RPSF into the transfer aisle, where much of the same stacking prep work being practiced now by EGS and Jacobs would be performed.

For SLS, the final preparation work in the VAB before stacking segments will be done as is being rehearsed now, in High Bay 4. “It’s a very, very similar process that we did in Shuttle,” Chreist explained. “This time we’re starting it in High Bay 4.”

“We’re going to come over from the RPSF and we’re pretty much going to start with the aft assembly coming in,” Chreist said. “It comes into High Bay 4 and then at that point our folks that have got all the training there, our stations all set up there, they’re already familiar with the area, [so] it makes sense to come on in, we’ve got our transportation [route] set up.”

A crane lifting a Shuttle booster segment in the VAB in 2004 after clearing the 16th floor crossover into High Bay 3. Credit: NASA

“We’ll hook up the 384 lifting beam, we’ll pick up the aft segment assembly and of course there’s preps and so forth associated with all of that. We’ll take it up and over the crossover into High Bay 3, we’ll perform our clears, get that all set up and put that aft assembly onto the ML posts.”

“And then we move on to the different segments we have,” he continued. “They’re very, very similar. We’ll bring it up over onto the slap stand, we’ll do all our preps, and we’ll take it up and over. We’ll take it up and over the crossover into High Bay 3, we’ll perform our clears, get that all set up and put that aft assembly onto the ML posts.”

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