The S-61L first flew on 2 November 1961. It is was 4ft 3in (1.27m) longer than the standard S-61A/HSS-2/SH-3 in order to carry freight or passengers. Initial production S-61Ls were powered by two 1350shp (1005kW) GE CT58-140 turboshafts. The S-61L features a modified landing gear with straight strut legs on each side. Los Angeles Airways was the first civil operator of the S-61L, introducing them on 11 March 1962. Many S-61Ls were subsequently updated to Mk II standard with more powerful CT58-110 engines, vibration damping and other detail refinements.