Viper 7242 is a Viper Mk. II spacefighter, which was apparently the favored craft of Bill "Husker" Adama during much of the Cylon War. It was found "rusting out in a salvage yard on Sagittaron" by CPO Galen Tyrol, who restores it to operational condition and presents it as a token of thanks to his retiring commanding officer.
The fighter is flown by Adama's son, Lee "Apollo" Adama, in a flyby performance during Galactica's decomissioning. The younger Adama is assigned escort duty for Colonial Heavy 798 back to Caprica. When the Cylon Attack begins without warning, the fighter's comparably antiquated systems proved impervious to Cylon infiltration attempts. Adama successfully protects Colonial Heavy 798 and its passenger, Laura Roslin, long enough for them to gather a sizeable refugee fleet of other stranded civilian ships and rendezvous with Galactica at Ragnar Anchorage.
At the subsequent battle to escape a Cylon blockade, Apollo, now the battlestar's CAG, commands Galactica's defensive squadrons of Vipers from the same fighter. The ship sustains major damage to its engine assembly, but returns to Galactica's landing bay by the timely intervention and unconventional flying of Kara "Starbuck" Thrace.
The damage to Viper 7242 is repaired amidst the constant Cylon attacks during the first week after the Fleet's escape from Ragnar (33).