Most developmental work in business aircraft engines is taking place at each end of the spectrum: light turboprops and large-cabin, long-range business jets. Meanwhile, gas and smoke emission rules are evolving, especially with the addition of CO₂ as a target. AIN talked to GE, Honeywell, Pratt & Whitney Canada, Rolls-Royce, Snecma and Williams International. The EASA provided an insight into the advancing environmental rules.