(a) General. The holder of an air carrier operating certificate or an operating certificate issued under part 125 may conduct a ferry flight of a four-engine airplane or a turbine-engine-powered airplane equipped with three engines, with one engine inoperative, to a base for the purpose of repairing that engine subject to the following:

1. (1) The airplane model has been test flown and found satisfactory for safe flight in accordance with paragraph (b) or (c) of this section, as appropriate. However, each operator who before November 19, 1966, has shown that a model of airplane with an engine inoperative is satisfactory for safe flight by a test flight conducted in accordance with performance data contained in the applicable Airplane Flight Manual under paragraph (a)(2) of this section need not repeat the test flight for that model.

2. (2) The approved Airplane Flight Manual contains the following performance data and the flight is conducted in accordance with that data:

   1. (i) Maximum weight.
   2. (ii) Center of gravity limits.
   3. (iii) Configuration of the inoperative propeller (if applicable).
   4. (iv) Runway length for takeoff (including temperature accountability).
   5. (v) Altitude range.
   6. (vi) Certificate limitations.
   7. (vii) Ranges of operational limits.
   8. (viii) Performance information.
   9. (ix) Operating procedures.

3. (3) The operator has FAA approved procedures for the safe operation of the airplane, including specific requirements for—

   1. (i) Limiting the operating weight on any ferry flight to the minimum necessary for the flight plus the necessary reserve fuel load;
   2. (ii) A limitation that takeoffs must be made from dry runways unless, based on a showing of actual operating takeoff techniques on wet runways with one engine inoperative, takeoffs with full controllability from wet runways have been approved for the specific model aircraft and included in the Airplane Flight Manual:
   3. (iii) Operations from airports where the runways may require a takeoff or approach over populated areas; and
   4. (iv) Inspection procedures for determining the operating condition of the operative engines.

4. (4) No person may take off an airplane under this section if—

   1. (i) The initial climb is over thickly populated areas; or
   2. (ii) Weather conditions at the takeoff or destination airport are less than those required for VFR flight.
5. (5) Persons other than required flight crewmembers shall not be carried during the flight.
6. (6) No person may use a flight crewmember for flight under this section unless that crewmember is thoroughly familiar with the operating procedures for one-engine inoperative ferry flight contained in the certificate holder's manual and the limitations and performance information in the Airplane Flight Manual.

(b) Flight tests: reciprocating-engine-powered airplanes. The airplane performance of a reciprocating-engine-powered airplane with one engine inoperative must be determined by flight test as follows:

1. (1) A speed not less than 1.3 VS1 must be chosen at which the airplane may be controlled satisfactorily in a climb with the critical engine inoperative (with its propeller removed or in a configuration desired by the operator and with all other engines operating at the maximum power determined in paragraph (b)(3) of this section.

2. (2) The distance required to accelerate to the speed listed in paragraph (b)(1) of this section and to climb to 50 feet must be determined with—

   1. (i) The landing gear extended;
   2. (ii) The critical engine inoperative and its propeller removed or in a configuration desired by the operator; and
   3. (iii) The other engines operating at not more than maximum power established under paragraph (b)(3) of this section.
3. (3) The takeoff, flight and landing procedures, such as the approximate trim settings, method of power application, maximum power, and speed must be established.
4. (4) The performance must be determined at a maximum weight not greater than the weight that allows a rate of climb of at least 400 feet per minute in the en route configuration set forth in § 25.67(d) of this chapter in effect on January 31, 1977, at an altitude of 5,000 feet.
5. (5) The performance must be determined using temperature accountability for the takeoff field length, computed in accordance with § 25.61 of this chapter in effect on January 31, 1977.

(c) Flight tests: Turbine-engine-powered airplanes. The airplane performance of a turbine-engine-powered airplane with one engine inoperative must be determined by flight tests, including at least three takeoff tests, in accordance with the following:

1. (1) Takeoff speeds VR and V2, not less than the corresponding speeds under which the airplane was type certificated under § 25.107 of this chapter, must be chosen at which the airplane may be controlled satisfactorily with the critical engine inoperative (with its propeller removed or in a configuration desired by the operator, if applicable) and with all other engines operating at not more than the power selected for type certification as set forth in § 25.101 of this chapter.

2. (2) The minimum takeoff field length must be the horizontal distance required to accelerate and climb to the 35-foot height at V2 speed (including any additional speed increment obtained in the tests) multiplied by 115 percent and determined with—

   1. (i) The landing gear extended;
   2. (ii) The critical engine inoperative and its propeller removed or in a configuration desired by the operator (if applicable); and
   3. (iii) The other engine operating at not more than the power selected for type certification as set forth in § 25.101 of this chapter.
3. (3) The takeoff, flight, and landing procedures such as the approximate trim setting, method of power application, maximum power, and speed must be established. The airplane must be satisfactorily controllable during the entire takeoff run when operated according to these procedures.

4. (4) The performance must be determined at a maximum weight not greater than the weight determined under § 25.121(c) of this chapter but with—

   1. (i) The actual steady gradient of the final takeoff climb requirement not less than 1.2 percent at the end of the takeoff path with two critical engines inoperative; and
   2. (ii) The climb speed not less than the two-engine inoperative trim speed for the actual steady gradient of the final takeoff climb prescribed by paragraph (c)(4)(i) of this section.
5. (5) The airplane must be satisfactorily controllable in a climb with two critical engines inoperative. Climb performance may be shown by calculations based on, and equal in accuracy to, the results of testing.

6. (6) The performance must be determined using temperature accountability for takeoff distance and final takeoff climb computed in accordance with § 25.101 of this chapter.

   For the purpose of paragraphs (c)(4) and (5) of this section, two critical engines means two adjacent engines on one side of an airplane with four engines, and the center engine and one outboard engine on an airplane with three engines.