Special Military Team Searches For Aircraft Cracks

All combat aircraft go through extreme stresses when completing their missions. Those stresses can cause metal fatigue -- tiny cracks in the joints and welds of the frame or invisible fractures in the metal.

The sooner these invisible cracks are found, the safer the aircraft will be.

Finding those cracks in a deployed environment, where every aircraft is critical and ensuring they are fully operational is of premium importance, is the mission for three airmen at the Bagram Airbase in Afghanistan. The nondestructive inspection team is part of the fabrication flight and uses various techniques to find cracks in the metal on aircraft here, said Senior Airman Ryan Michalec, of the 354th Expeditionary Aircraft Maintenance Squadron.

"We use different scientific methods to find those cracks that can’t be seen by the unaided eye, as well as those which can," he said.

The tools the team uses are fairly similar to those they use at home; however, the tools here are portable.

"We had an X-ray machine that we couldn’t bring because of its size," said Staff Sgt. Brooke Wilke, a team member. "The portable equipment takes a little more time, on occasion. For example, inspecting the A-10 (Thunderbolt II) main landing gear wheel bolts (takes) a little more time with the magnetic particle unit we have here instead of the equipment we would use at home."

This gives team members experience with many different pieces of equipment.

"I’ve gotten a lot of training [that] I wouldn’t have at home," said team member Airman 1st Class Kevin Louie. "I have gotten the chance to work with other services and on other air frames, [too]."

The goal for the team is to avert catastrophic problems without tearing up the airplane to find them.

"It takes us a few minutes to find cracks; it may take some time for a maintenance crew to get to and repair," said Sergeant Wilke.

The team uses many different processes to find metal fatigue. For instance, with one technique, the technician places a long, thin probe on the aircraft part.

"The probe creates a magnetic current in the metal. We can read changes in that current [called an eddy current] to determine where the cracks are," Airman Michalec said.

He explained the process by using the analogy of throwing a stone into still water. The stone causes eddies in the water, and any obstruction in the water will cause a disruption in the smooth progression of the eddies.

Another technique uses ultrasonic sound waves to locate cracks.

"If there’s a crack in a part, you get a signal loss or a reduced signal from the ultrasound, if you use this technique," Airman Louie said.

Not everything is as technically complex. One of the techniques used most often by the team is oil analysis, where the technician checks how much worn metal is in the engine oil by burning a sample in a special machine.

"We can determine if an engine is starting to go bad by examining the oil," Sergeant Wilke said. "Sometimes you can go a long time before getting a ‘hit’ indicating a deteriorating engine, and then you might have one or two in a few weeks."

So far, in the four months the team has been deployed to Afghanistan, it has had two "hits" on A-10 engines and one on an MH-47 helicopter transmission, Sergeant Wilke said.

"The level of flying hours here (generates) a lot more activity on the aircraft [because] each plane flies regularly," she said. "That makes a lot more oil samples for us to check."

Keeping the aircraft safe is extremely important to the team.

"I want to do anything I can to prevent a show-stopper -- something that will keep the aircraft from doing its mission," Airman Michalec said. "If no one was checking, we might have more mishaps. This job is really important. It makes me feel good to know I have such a vast impact in keeping the plane operational."

The focus on nondestructive inspections sets the team apart from other services as well.

"In most of the other services, this job is in addition to the maintainers’ normal job," Airman Michalec said. "We are dedicated to this mission and are specifically trained to do it."

(ANN salutes Master Sgt. Andrew Gates, 455th Expeditionary Operations Group Public Affairs, USAF)

FMI: www.af.mil