Something was off with a key component used to literally hold many U.S. Air Force aircraft together—and it resulted in the service grounding 207 vital aircraft according to a Time Compliance Technical Order issues in February. No—it’s wasn’t the Air Force’s numerous F-16 tactical fighters. Nor its new F-35 stealth jets, or venerable B-52 bombers and A-10 ground attack jets. Foremost, it was the workhorse keeping all of those planes refueled in the sky: the service’s airliner-based KC-135 Stratotanker. It also affected RC-135 and WC-135 surveillance aircraft extensively deployed to monitor the activity and technologies of foreign militaries (particularly China,...