Newly designed chamber increases aircraft safety
by Crystal Toenjes
72nd Air Base Wing Public Affairs
4/25/2005 - TINKER AIR FORCE BASE, Okla. (AFPN) -- Technicians in the Tank and Cooler Unit at the Oklahoma City Air Logistics Center here push the limits of weapons systems to ensure their safety in the field, sometimes with explosive results.
“One of our prime tasks is doing proof pressure testing … before sending them to the field,” said Steven Coy, shop supervisor. “We blow things up, and we want them to blow up here and not on the aircraft.”
During tests, fuel and oil coolers and tanks are pressurized in a containment chamber 150 to 200 percent of operating pressure to make sure they will withstand above-normal operational requirements, Mr. Coy said.
“Every weapons system comes through this shop, both the aircraft and the engines,” he said.
The need for a new chamber became all too clear when the technicians were testing a new type of part and it experienced a catastrophic failure.
The incident nearly resulted in injuries Mr. Coy said.
The design process for a new chamber took about two weeks, said Don Ngo, facility engineer, and the final cost to build it was less than $40,000.
“My design gets the test mechanic out of harm’s way,” he said. “We have a test console with a TV so he can monitor the testing procedures on the screen or he can look through the windows.”
The windows are made of bullet-proof glass, and the chamber has been constructed with one-and-a-half inch thick steel doors on the front and top.
“When it locks down, it has … overlap areas,” Mr. Coy said. “The front doors lock together, and top section lowers with a latch to hold the doors more securely.”
Mr. Ngo said he wanted to incorporate new technologies like the internal camera, the separate testing console and three different testing circuits allowing different items to be tested at the same time.
“We’ll take a part and strap it in with bungee cords and then submerge it in water,” Mr. Coy said. “The water diffuses all the pressure so when it explodes you have a (wave), but it’s contained”
Submerging the part in water also allows the technicians to identify any leaks that may not be large enough to cause a failure, but could still cause operational problems, he said.
Mr. Ngo specifically designed the device to take as much as 700 pounds of pressure per square inch, but the technicians are not allowed to go past 500 psi when testing.
“When you have explosion, you have air and water under pressure,” he said.
That pressure is routed through pipes in the back of the chamber and directed down and out to depressurize the unit.
“We have a separate device that once the mechanic starts to pressurize the item (he or she) can’t open the door, and once you open the door, it automatically depressurizes the items,” Mr. Ngo said. “That’s another safety feature we have now.”
The old unit would remain pressurized even if the lid was opened, Mr. Coy said.
The new explosive containment chamber has taken most of the workload from its 50-year-old predecessor. Because it is several times larger than the previous unit, it has also broadened the types of parts that can be tested.
“This is a vast improvement in safety and production,” Mr. Coy said. “Weapons systems have gotten bigger and more elaborate … this probably increased our testing capability five fold.”
“You can’t even compare it to the old unit,” said Russell Keene, metal tank and radiator repairer. “It’s safer and clean up is easier. It’s just a thousand times better.” |
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