Following approval several months ago of RVSM equipment in the JetStar II, Duncan Aviation reported that it has received group approval for RVSM operations for the four-engine business jet. Last February, the Lincoln, Neb.-based company completed the installation and certification of dual IS&S altimeter/air data units in a JetStar 731, the first step in adding these aircraft to group RVSM approval. The installation includes an analog interface device that will provide digital-to-analog coupling to properly interface with the autopilot and flight director. RVSM certification will be priced at about $175,000 per aircraft. Duncan said the group approval will not include some JetStar 731s because they lack key avionics common to the group.