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NDI has mettle to find metal cracks

  • Published
  • By Staff Sgt. Marcus Morris
  • 18th Wing Public Affairs
KADENA AIR BASE, Japan --  During an F-15 Eagle pre-flight inspection, a crew chief discovers a crack in the paint. Because flaws in aircraft components can be potentially catastrophic, he strips it down to bare metal and calls the 18th Equipment Maintenance Squadron Nondestructive Inspection Flight.

NDI uses several techniques to check the structural integrity of metal aircraft components and ground equipment without impairing their future functionality. Using these techniques, they ensure vehicles tools, and parts are safe from unseen threats.

"We are preventative maintenance, said Tech. Sgt. Tobi Wilson, 18th EMS NDI craftsman. "We do not turn wrenches over here, and we don't fix anything, so a lot of people compare us to quality assurance, but we are inspectors. We are the first go-to shop when agencies think there is a crack or find something wrong. We will let them know if the part is serviceable, and then the other appropriate agencies will come out and fix it if it's not."

Most cracks are microscopic, but even a small crack could ultimately bring down a full aircraft if missed. NDI's range of specialized equipment, such as eddy current, X-ray, dye penetrant and ultra-sonic scanners allow NDI to check the surface and subsurface of parts for these nearly invisible flaws, saving the military money by identifying defects before they become major problems.

Besides searching for cracks, NDI also tests aircraft oil with their Joint Oil Analysis Program, which is standardized across the services. NDI checks oil before it is used to make sure there are no harmful chemicals mixed in and again after flight to identify potential problems with an engine.

"They'll take oil samples and we analyze them to let them know if there is anything breaking down in that engine," said Wilson. "If one of the elements has peaked, based on the trend we have for that particular engine, they will not fly that aircraft that day until we determine what is going on with that engine, because we don't want to send anything up in the air if there is something wrong with it."

Not only does NDI test more than 3,500 in-shop parts and aircraft per year for the agencies on Kadena, they also support the other U.S. services on the island including the Marine Corps, the Navy and the Army.

"We've helped Futenma and been up to White Beach and we help every other base on the island if they need it," said Wilson. "We do the JOAP for the Marines' Ospreys and the UH-60 Blackhawk for the Army folks here, and we've done weld certifications for the Marines. Sometimes they do have their version of us, but if they don't or they're lacking certain equipment, then they come to us to see if we can help."

Wilson went on to say that NDI is critical to the mission, because aircraft cannot fly their next sortie until NDI tells them that their engines are okay to fly, so that is one of their more critical programs they have.

Last November, the NDI upgraded their X-ray system from manually processing film to a digital version. This allowed them to cut most of their silver recovery program and removed jamming issues with the old machine.

"This new machine saves us a lot of hours and money," said Staff Sgt. Charles Sothikhoun, 18th EMS NDI technician. "We now use plates that hold the imagery that can be used up to 1000 times each and we can digitally zoom in on an image and change the sharpness, contrast or brightness allowing us to see more details and find FOD [foreign object debris] easier. With the old film, we had to look really hard with a magnifying glass to find cracks or FOD, and if the film was too exposed or too dark, we would have to reshoot it." 

Sothikhoun closed by saying his favorite part about NDI is being able to go to all the different aircraft and work on them with all of their equipment and techniques.

The Airmen in NDI use their knowledge to keep Okinawa's aircraft and equipment operational in support of missions throughout the Pacific Air Force.