The U.S. Air Force said on August 19 that it recently grounded 82 two-seat F-16D fighters following the discovery of canopy sill longeron cracks between the front and rear pilot seats. An “immediate action time compliance technical order” the service issued after post-mission flight inspections revealed initial structural cracks led to the discovery.
Individual F-16 units inspected the service’s 157 F-16Ds, and as of August 18 all fighters had been inspected, the Air Force said. Cracks were discovered on 82; the remaining 75 returned to flight status.
The F-16D fleet is used primarily for training, the Air Force said. The fighters are 24 years old on average, with more than 5,500 flight hours logged. The service has 969 F-16s of all variants; other variants are not affected.
“As aircraft accumulate flight hours, cracks develop due to fatigue from sustained operations,” stated Lt. Col. Steve Grotjohn, Weapons System Division deputy chief. “Fortunately, we have a robust maintenance, inspection and structural integrity program to discover and repair deficiencies as they occur.”
The Air Force F-16 systems program office and Lockheed Martin engineers were analyzing the F-16 structure and developing repair procedures. Fighters with cracks will be allowed to resume operations “for a limited number of flight hours while analysis continues on a permanent fix,” the service said.
“Programmed flying training and F-16 pilot graduation impacts will depend on the number and timing of aircraft returned to service," the statement said. “Subject-matter experts are considering multiple courses of action to mitigate these delays.”