 On 26 February 1958, the first unit to become operational with the F-104A was the 83rd Fighter Interceptor Squadron at Hamilton AFB, California.The newly operational aircraft experienced problems with both the J79 engine and M61 cannon, and after three months of service, the unit was grounded following a series of engine-related accidents.The aircraft were then fitted with the J79-GE-3B engine and another three ADC units were equipped with the F-104A.