297.25—Cancellation or conditioning of registration.
         The registration of a foreign indirect air carrier may be canceled or subjected to additional terms, conditions or limitations if:
    
    
        
        (a) 
         It files with the Department a written notice that it is discontinuing foreign indirect air carrier activities;
    
    
    
    
        
        (d) 
         A substantial ownership or control interest is acquired by persons who are not citizens of the country of citizenship of the registrant;