A rotational jack assembly is provided to support a portion of a trailer. The jack assembly has a pivot mount with a pivot axis, a mounting plate rotatable about the pivot axis and a pin receptor with a first and second portion. The mounting plate carries a support assembly and a locking pin. The locking pin is engagable with the pin receptor, and adapted to move between the first and second portions of the pin receptor upon application of rotational force. A force activated locking assembly and a breakaway support assembly are also provided for supporting a portion of a trailer. A method of use for the rotational breakaway trailer jack assembly is also disclosed.