14 CFR 23.66 - Takeoff climb: One-engine inoperative.
For normal, utility, and acrobatic category reciprocating engine-powered airplanes of more than 6,000 pounds maximum weight, and turbine engine-powered airplanes in the normal, utility, and acrobatic category, the steady gradient of climb or descent must be determined at each weight, altitude, and ambient temperature within the operational limits established by the applicant with -
(b) The remaining engine(s) at takeoff power;
(c) The landing gear extended, except that if the landing gear can be retracted in not more than seven seconds, the test may be conducted with the gear retracted;
(d) The wing flaps in the takeoff position(s):
(e) The wings level; and