14 CFR §194.308

1. (a)Persons operating powered-lift in commercial air tours must continue to comply with rules applicable to all aircraft in part 136 of this chapter, as applicable to the operation.
2. (b)Suitable landing area, as defined in § 136.1 of this chapter, applies to powered-lift conducting commercial air tours.
3. (c)Critical change of thrust for purposes of this section means a failure that would most adversely affect the performance or handling qualities of an aircraft.
4. (d)No person may operate a powered-lift in a commercial air tour unless that person complies with the regulations listed in the first column of table 1 to this section, notwithstanding their applicability to airplanes or rotorcraft, subject to the applicability provisions in the second column, and any additional requirements or clarification specified in the third column: