14 CFR 23.363 - Side load on engine mount.
(a) Each engine mount and its supporting structure must be designed for a limit load factor in a lateral direction, for the side load on the engine mount, of not less than -
(1) 1.33, or
(2) One-third of the limit load factor for flight condition A.
(b) The side load prescribed in paragraph (a) of this section may be assumed to be independent of other flight conditions.