The Regs are a little vague on spins, 91.303 defines aerobatic flight as any that results in an abrupt change in pitch, bank or airspeed and states you need a 'chute but that's about it. AC61-57C outlines stall and spin training.


From AC61-67C:

301. SPIN TRAINING AND PARACHUTES. Part 91, section 91.307(c), prohibits the pilot of a civil aircraft from executing any intentional maneuver that exceeds 60° of bank relative to the horizon, or exceeds 30° noseup or nosedown attitude relative to the horizon, unless an approved parachute is worn by each occupant (other than a crewmember). Section 91.307(d) states, in pertinent part, that section 91.307(c) does not apply to flight tests for a pilot certificate or rating; or spins and other flight maneuvers required by the regulations for any certificate or rating when given by a certified flight instructor (CFI) or an airline transport pilot (ATP) instructing in accordance with section 61.167.
a. Section 61.183(i) requires an applicant for a flight instructor certificate or rating to receive flight training in stall awareness, spin entry, spins, and spin recovery procedures. The applicant must also possess and demonstrate instructional proficiency in these areas to receive the certificate or rating.
b. Because spin entry, spins, and spin recovery are required for a flight instructor certificate or rating, a person receiving instruction from a CFI (or an ATP instructing in accordance with section 61.167) need not wear an approved parachute while instruction is being provided in these maneuvers. This provision applies regardless of the certificate or rating for which the person is receiving training and also if the person is receiving instruction that is not being provided for the purpose of obtaining any additional certificate or rating. The instructor providing the training is also not required to wear an approved parachute while providing this flight training.
c. Additionally, it should be noted that any pilot or required crewmember may perform a maneuver that exceeds the limits prescribed in section 91.307(c) without wearing an approved parachute, provided there are no other occupants in the aircraft or the other occupants are wearing approved parachutes