1. (a) Loads and equilibrium. For limit ground loads—

   1. (1) Limit ground loads obtained under this subpart are considered to be external forces applied to the airplane structure; and
   2. (2) In each specified ground load condition, the external loads must be placed in equilibrium with the linear and angular inertia loads in a rational or conservative manner.

2. (b) Critical centers of gravity. The critical centers of gravity within the range for which certification is requested must be selected so that the maximum design loads are obtained in each landing gear element. Fore and aft, vertical, and lateral airplane centers of gravity must be considered. Lateral displacements of the c.g. from the airplane centerline which would result in main gear loads not greater than 103 percent of the critical design load for symmetrical loading conditions may be selected without considering the effects of these lateral c.g. displacements on the loading of the main gear elements, or on the airplane structure provided—

   1. (1) The lateral displacement of the c.g. results from random passenger or cargo disposition within the fuselage or from random unsymmetrical fuel loading or fuel usage; and
   2. (2) Appropriate loading instructions for random disposable loads are included under the provisions of § 25.1583(c)(2) to ensure that the lateral displacement of the center of gravity is maintained within these limits.
3. (c) Landing gear dimension data. Figure 1 of appendix A contains the basic landing gear dimension data.

[Amdt. 25-23, 35 FR 5673, Apr. 8, 1970, as amended by Doc. No. FAA-2022-1355, Amdt. 25-148, 87 FR 75710, Dec. 9, 2022; 88 FR 2813, Jan. 18, 2023]