91.1007—Flights conducted under part 121 or part 135 of this chapter.
        
        (a) 
         Except as provided in  § 91.501(b), when a nonprogram aircraft is used to substitute for a program flight, the flight must be operated in compliance with  part 121 or  part 135 of this chapter, as applicable.
    
    
        
        (b) 
         A program manager who holds a certificate under  part 119 of this chapter may conduct a flight for the use of a fractional owner under  part 121 or  part 135 of this chapter if the aircraft is listed on that certificate holder's operations specifications for  part 121 or  part 135, as applicable.
    
    
        
        (c) 
         The fractional owner must be informed when a flight is being conducted as a program flight or is being conducted under  part 121 or  part 135 of this chapter.