"Our primary concern is the safety of our Airmen and it is imperative that they have confidence in our equipment," Major General Craig Wills, 19th Air Force Commander, said in a statement.

"This is a temporary stand-down, not a fleet-wide grounding," Air Force spokeswoman Ann Stefanek said in a statement about concern over "a component used in the pilot ejection system of several aircraft."

Lockheed Martin F-35s have Martin-Baker ejection seats, the Air Force said, and the service will "execute a stand-down on July 29 to expedite the inspection process" of those systems.

The Air Force's training fleet is also impacted, the Air Force said. "We suspect that approximately 203 T-38 and 76 T-6 aircraft may be affected by this issue. This number represents approximately 40% of our T-38 fleet and 15% of our T-6 fleet."

(Reporting by Mike Stone in Washington; Editing by Paul Simao)

By Mike Stone