14 CFR § 91.313 - Restricted category civil aircraft: Operating limitations.
(1) For other than the special purpose for which it is certificated; or
(2) In an operation other than one necessary to accomplish the work activity directly associated with that special purpose.
(b) For the purpose of paragraph (a) of this section, the following operations are considered necessary to accomplish the work activity directly associated with a special purpose operation:
(2) Flights conducted to satisfy proficiency check and recent flight experience requirements under part 61 of this chapter provided the flight crewmember holds the appropriate category, class, and type ratings and is employed by the operator to perform the appropriate special purpose operation.
(c) No person may operate a restricted category civil aircraft carrying persons or property for compensation or hire. For the purposes of this paragraph (c), a special purpose operation involving the carriage of persons or material necessary to accomplish that operation, such as crop dusting, seeding, spraying, and banner towing (including the carrying of required persons or material to the location of that operation), an operation for the purpose of providing flight crewmember training in a special purpose operation, and an operation conducted under the authority provided in paragraph (h) of this section are not considered to be the carriage of persons or property for compensation or hire.
(1) Is a flight crewmember;
(2) Is a flight crewmember trainee;
(3) Performs an essential function in connection with a special purpose operation for which the aircraft is certificated;
(4) Is necessary to accomplish the work activity directly associated with that special purpose; or
(5) Is necessary to accomplish an operation under paragraph (h) of this section.
(e) Except when operating in accordance with the terms and conditions of a certificate of waiver or special operating limitations issued by the Administrator, no person may operate a restricted category civil aircraft within the United States -
(1) Over a densely populated area;
(2) In a congested airway; or
(3) Near a busy airport where passenger transport operations are conducted.
(g) No person may operate a small restricted-category civil airplane manufactured after July 18, 1978, unless an approved shoulder harness or restraint system is installed for each front seat. The shoulder harness or restraint system installation at each flightcrew station must permit the flightcrew member, when seated and with the safety belt and shoulder harness fastened or the restraint system engaged, to perform all functions necessary for flight operation. For purposes of this paragraph -
(2) A front seat is a seat located at a flight crewmember station or any seat located alongside such a seat.
(1) An operator may apply for deviation authority from the provisions of paragraph (a) of this section to conduct operations for the following purposes:
(i) Flight training and the practical test for issuance of a type rating provided -
(B) The pilot receiving flight training is employed by the operator to perform a special purpose operation; and
(C) The flight training is conducted by the operator who employs the pilot to perform a special purpose operation.
(2) The FAA will issue this deviation authority as a letter of deviation authority.
(3) The FAA may cancel or amend a letter of deviation authority at any time.
(4) An applicant must submit a request for deviation authority in a form and manner acceptable to the Administrator at least 60 days before the date of intended operations. A request for deviation authority must contain a complete description of the proposed operation and justification that establishes a level of safety equivalent to that provided under the regulations for the deviation requested.