A failure in any part of Arnold’s cooling water system can result in lost test time, program delays and considerable cost overruns.
Approximately five years ago, inspections conducted on the eight pumps at the Secondary Pumping Station (SPS) revealed significant wear, beyond what scheduled and condition-based preventive maintenance could address.
“These pumps were originally installed in 1950,” said Jeff Quattlebaum, the cooling water systems engineer with ATA’s reliability engineering branch.
It helps to understand how the entire system works. The base’s Primary Pumping Station draws water four miles from Woods Reservoir to fill a 56 million gallon capacity secondary reservoir. Then the Secondary Pumping Station is used to pull water from this source and routes it to and from all of the testing facilities. The water is eventually filtered of any contaminants and then returned to Woods Reservoir.
Quattlebaum realized a major upgrade to the SPS’s 25,000 gallons-per-minute pumps would be necessary in a couple of years, unless he could find a way to replace the impellers that drive the water through the pumps and throughout the base where it’s needed.
“The impeller itself is the big rotating element that moves the water,” he explained. “Impellers transfer energy from the motor driving the pump to the water being pumped by accelerating the fluid outwards from the center of rotation.”
The company that originally manufactured the pumps at the Secondary Pumping Station was contacted with the aim of having new impellers fabricated to replace the aging ones in the facility’s pumps.
“Probably within three or four months we got the word back that they don’t make those anymore, that model had been discontinued,” Quattlebaum recalled. “They told me, ‘All we can do is sell you a new pump for somewhere between a half and three quarters of a million dollars.’”
As it turned out, not only did the company no longer make the impellers, they no longer had the plans or molds for them either. Finally, he realized that whatever that company had in the way of the original plans or a model of the impeller had ended up at AEDC.
“After a week-long search, we found a crate that hadn’t been opened or touched since 1967. It had a bunch of cardboard and plywood pieces [inside], but these weren’t like a mold you could pour something into, it was the thing they built the mold from.”
Mike Barlow, ATA’s utilities operation manager, said the entire effort to keep the Secondary Pumping Station, which in turn is key to keeping AEDC operational is noteworthy.
“The Secondary Pumping Station (SPS) pump impellers replacement is a prime example of sound service life extension, perseverance and team work,” he said. “The 60-year old pumps and motors at the SPS are well maintained via our preventive maintenance program using proven condition based maintenance strategies and techniques. The right maintenance, combined with impeller replacement, will extend the service life of these eight pumps for another 60 years, or more.”
Barlow had praise for those who took the initiative to ensure the Secondary Pumping Station functions for years to come, especially when the cost avoidance involved is taken into consideration.
“Replacement of the impellers at a cost of approximately $30,000 each is much less than the $750,000 it would cost to replace each of the pumps and motors - a huge savings to AEDC,” Barlow said. “Several years ago, Jeff [Quattlebaum] recognized the value of replacing the impellers.”
Eventually, the original manufacturer decided to fabricate the impellers and this was facilitated by the vintage contents of the crate found in the main warehouse.
Barlow said, “Now all Jeff needed was funding and this is where the team work came into play. He approached his financial contact, Marcheta Darnell, about the need. She worked with her Air Force counterpart, Allen Fleenor, and they were successful at identifying funds to purchase the impellers.”
Last month, the first impeller was built, installed, and successfully checked out, according to Quattlebaum.
Quattlebaum also gave credit to the craft workers who are instrumental in ensuring the whole system functions properly, including the new impeller.
“Our machinists repair, rebuild and perform all of the maintenance to the large pumps on base, including the Primary Pumping Station at Woods Reservoir, Secondary Pumping Station, the cooling towers, return basin and pump at Roland Creek,” said John Richardson, a utilities supervisor with ATA’s test and facility support branch.
Barlow, referring to the recently installed impeller, said, “It works great. Based on that success, seven more impellers are being made. We will install those as each pump is taken out of service for maintenance. This will avoid additional outages and negate the expense of impeller installation.
“Sound maintenance strategies, a lot of perseverance, and a little team work result in an effort that allows AEDC to keep performing its mission for years to come and a great sense of ‘job well done’ for all those involved.”
Aerospace Testing Alliance utility machinists, (left to right) Nat Farrar, Reggie Sizemore and David Stewart set the clearance on the new shaft for the recently fabricated impeller before it was installed at the Secondary Pumping Station (SPS). The 25,000 gallon-per-minute impellers are being replaced to help the efficiency and flow of the cooling water that is used throughout the facilities. These SPS pumps, which weigh between five to six tons each, deliver as much as eight billion gallons of water around the base each year to maintain the proper temperatures for conducting tests of jet engines, aircraft models, rocket motors and other flight systems and components. (Photo by Rick Goodfriend)
ATA Utility Machinist David Stewart operates a large lathe in the Model Shop. He is machining the shaft assembly supporting the recently fabricated impeller for a pump that is located in AEDC’s Secondary Pumping Station.