§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 Vy 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-persecond gusts acting normal to the flight Dath in level flight. The gust load faetors shall be computed by the formula of § 3.188. V; shall be assumed not less than 1.4 Vs or 1.8 Vs, whichever is greater, where: V,=the computed stalling speed with flaps fully retracted at the design welght V,;=the computed stalling speed with flaps Tully 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. Nore: In determining the external loads on the airplane as a whole, the thrust, slipstream, and pitching acceleration may be assumed equal to zero. UNSYMMETRICAL FLIGHT CONDITIONS