Required for the assembly of dynein arms in the distal portion of flagellum axoneme. Localizes to the distal portion of the flagellum. Gene knockout results in significant reduction of flagellar beating and cell swimming, and absence of outer dynein arms in the distal region of flagellum axoneme. Cell motility is characterized by an erratic swimming pattern with altered propagation of the tip-to-base wave, increased frequency of base-to-tip waves, and frequent tumbling typical of outer dynein arm mutants. Belongs to the LRRC56 family.