Catalysis of the reaction: (Kdo)2-lipid A + 2 4-amino-4-deoxy-alpha-L-arabinopyranosyl di-trans,poly-cis-undecaprenyl phosphate = (beta-L-Ara4N)2-(KDO)2-lipid A + 2 ditrans,polycis-undecaprenyl phosphate.
4-amino-4-deoxy-L-arabinose transferase activity