A more powerful, better performing Caravan 208 with improved fuel burn is the goal of Anchorage-based Aero Twin, which is working on a mod to convert the turboprop single from its original 675-shp P&WC PT6 to the 850-shp Honeywell TPE331-12JR-701S. Aero Twin, which first flew a prototype “850 Caravan” on October 2 and had expected to receive an STC for the conversion this spring, has pushed back its certification target to the fall. The program has been delayed because the FAA is now requiring compliance with new, more stringent STC regulations that went into effect last month, and apparently no grandfather clause was applied to this project, according to Aero Twin president Tony Cestnik.