6/29/2012 - ROBINS AIR FORCE BASE, Ga. -- Something is cooking inside Bldg. 169, home of the 574th Composite Repair Flight.
An imposing structure known as an autoclave, measuring 15-by-50 feet - the largest of three autoclaves at Robins and big enough to hold about a half dozen SUVs - sits ready on one side of the cavernous 146,000 square foot building. A second, smaller autoclave, which measures 10-by-20 feet, sits a short distance away; a third is housed in Bldg. 670.
Once a massive door closes on the largest autoclave, think of it as a vacuum-tight sealed chamber, secured much like a cap you twist on the top of a medicine bottle.
"It's like a big pressure cooker," said Wesley Wood, a 574th Commodities Maintenance Squadron supervisor.
Once various aircraft parts are bonded inside the shop, mainly C-5 assets, single repaired or newly-manufactured parts are wheeled inside the autoclave on specially-built tracks.
Depending on the order, the cylinder acts as a pressure vessel to expose parts to elevated pressures and temperatures. This can include leaving items inside from 90 minutes to two hours, in temperatures from 250 to 350 degrees.
A series of vacuum hoses inside the autoclave is hooked on special adhesives on an aircraft part. Once the outer door is closed, the large autoclave is heated and pressurized with nitrogen.
An operator sits in a small computer room just outside and monitors the process for any safety hazards until the process is completed.
"After a 'first cook' on an aircraft panel, for example, what will generally happen is skins are laid out that have been treated with a corrosion prohibitor," said Wood.
A metallic honeycomb structure is then put onto the part, which makes it lightweight and durable, he continued. An exterior skin is also added to enclose the honeycomb, before it's sent for a finishing paint job and on to its final destination.
An average of 20 to 30 items are routed through the various autoclaves on any given week. In addition to miscellaneous C-5 panels, other items processed include C-5 engine exterior covers, torque decks, floorboards, and pylon panels; C-130 boron repairs and C-17 composite work.
The autoclaves provide the "heartbeat" for the Composite Repair Flight's repair and manufacturing support to the C-5, C-17 and C-130 aircraft squadrons at Robins, as well as support to aircraft worldwide through the Defense Logistics Agency.