The United States Air Force has taken the dramatic step of grounding over half of an entire variant of one of its most well-known planes – the F-16 Fighting Falcon (or Viper, if you prefer its unofficial nickname). The grounding covers the two-seat F-16D variant, and was issued after the USAF discovered structural cracks in 82 of its 157 fighters.
The cracks were described as thin, and were found on the canopy longeron sill between the front and back seats of the popular, but aging, fighter. The F-16D is primarily used for training purposes nowadays, although that doesn't make this problem any less troubling.
According to Stars and Stripes, the USAF's F-16 Program Office said in a statement that it's developing a temporary fix alongside Lockheed Martin. That would allow the planes to fly in a limited capacity until a more permanent fix is sorted out.
The USAF currently maintains a fleet of nearly 1,000 F-16s.