Avidyne, Lincoln, Mass., received FAA approval to retrofit Cessna 300-series piston twin models with its Envision Integrated Flight Deck. Avidyne and Southern Star Avionics, Mobile, Ala., added the Cessna 320, 335 and 340 piston twins to the FAA Approved Model List of aircraft authorized for retrofit of the Envision System. Cessna’s 401, 402, 414 and 421 models were approved in March when the supplemental type certificate was originally granted.