Using the high-cadence lightcurves collected from the FOSSIL survey, rotation periods of 17 small (diameter 1km<D<3km) Hilda asteroids (hereinafter Hildas) were obtained. Combined with the previously measured rotation periods of Hildas, a spin-rate limit appears at around 3hr. Assuming rubble-pile structures for the Hildas, a bulk density of ~1.5g/cm^3^ is required to withstand this spin-rate limit. This value is similar to that of the C-type asteroids (1.33g/cm^3^) and higher than the ~1g/cm^3^ bulk density of the Jupiter Trojans. This suggests that the Hildas population may contain more C-type asteroids than expected, and the limit at 3hr simply reflects the spin-rate limit for C-type asteroids. In addition, a Hilda superfast rotator was found, which has a rotation period of 1.633hr and an estimated diameter of 0.7km. This object is unlikely to be explained by a rubble-pile or monolithic structure.