Complex sentence: He switched to the Albatros D.III in January 1917, scoring two victories before suffering an in-flight crack in the spar of the aircraft's lower wing on 24 January, and he reverted to the Albatros D.II or Halberstadt D.II for the next five weeks.
Split into simpler sentences: He switched to the Albatros D.III in January 1917, scoring two victories before suffering an in-flight crack in the spar of the aircraft's lower wing on 24 January. Richthofen reverted to the Albatros D.II or Halberstadt D.II for the next five weeks.