In 1976, the Bo 105CB, equipped with more powerful Allison 250-C20B engines, was introduced. The Bo 105C was further developed to become the Bo 105CBS, the primary change being a fuselage stretch of 10 inches to meet American demand for emergency medical service (EMS) operations; this version was often referred to as the Bo 105 Twin Jet in the United States. US aerospace firm Boeing-Vertol served as a partner in the type's production and further development, and marketed the BO 105 in the US. The Bo 105 CB and the Bo 105 CBS variants were also subject to license manufacturing agreements, leading to them being produced by the Philippine Aerospace Development Corporation in the Philippines, Indonesian Aerospace (IPTN) in Indonesia, and Construcciones Aeronáuticas SA (CASA) in Spain in addition to the main production line in Germany.