§3.190 Flaps extended flight conditions.

(a) When flaps or similar high lift devices intended for use at the relatively low air speeds of approach, landing, and take-off are installed, the airplane shall be assumed to be subjected to symmetrical maneuvers and gusts with the flaps fully deflected at the design flap speed Vf resulting in limit load factors within the range determined by the following conditions: (1) Maneuvering, to a positive limit load factor of 2.0. (2) Positive and negative 15-feet-per-second gusts acting normal to the flight path in level flight. The gust load factors shall be computed by the formula of § 3.188. Vf shall be assumed not less than 1.4 Vs of 1.8 Vsf whichever is greater, where: Vs = the computed stalling speed with flaps fully retracted at the design weight Vsf = the computed stalling speed with flaps fully extended at the design weight except that when an automatic flap load limiting device is employed, the airplane may be designed for critical combinations of air speed and flap position permitted by the device. (See also § 3.338.) (b) In designing the flaps and supporting structure, slipstream effects shall be taken into account as specified in § 3.223. where: Ev. = MOMent coetficient increment &é= down aileron detlection in degrees in critical condition Note: In determining the external loads on the airplane as a whole, the thrust, slip-stream, and pitching acceleration may be assumed equal to zero. UNSYMMETRICAL FLIGHT CONDITIONS