The team continues to fly the F-16, having switched from the F-16A to the F-16C in 1992.[3] Only a few minor modifications differentiate a Thunderbird from an operational F-16C. These include the replacement of the 20 mm cannon and ammunition drum with a smoke-generating system, including its plumbing and control switches, the removal of the jet fuel starter exhaust door, and the application of the Thunderbirds' glossy red, white, and blue polyurethane paint scheme. All the modification work is performed at the maintenance depot at Hill AFB near Ogden, Utah. Other than those modifications, the aircraft are taken from the standard USAF inventory as production fighters, and can be returned to an operational squadron in short order without any major modification.