The test plane is being used in what's called "durability ground testing," a normal test program in which testers apply cyclic loads to the airframe to simulate operational flying and identify any potential problems.
Such discoveries are expected during a developmental test program, DellaVedova stressed.
"The purpose of durability testing is to intentionally stress the aircraft to its structural limits so we can identify any issues and corrective actions needed to fix them," he said.
This type of testing will ensure the F-35's requirement for 8,000 flight hours, DellaVedova noted. During durability tests, the plane is tested to two lifetimes, or 16,000 flight hours, he explained.
The plane has 13 wing "spars," which are the main structural members of the wing.