The NTSB wants the FAA to require Pratt & Whitney Canada PT6A-60 starter-generators to be electrically isolated from the rest of the engine, a modification that is already in the works. The Safety Board also asked that the FAA require early Pilatus PC-12s (up to S/N 231) to be equipped with a magnetic chip detector (MCD) advisory and warning system that works while in flight, and require an accessory gearbox magnetic chip detector on PC-12s. The MCD warning system on these older PC-12s works only when the airplane is on the ground. Newer PC-12s (from S/N 232 onward) incorporate a revised system design that does not disable the MCD in flight (a Service Bulletin is available).